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Beginning Linux

1. So the only thing left to do is create an entry in etc fstab for my mount vi etc fstab LABEL ext3 defaults 11 LABEL boot boot ext3 defaults 12 none dev pts devpts gid 5 mode 620 00 LABEL home home ext3 defaults 12 none proc proc defaults 00 none dev shm tmpfs defaults 00 LABEL usr usr ext3 defaults 12 LABEL var var ext3 defaults 12 dev hda3 swap swap defaults 00 dev fd0 mnt floppy auto noauto owner kudzu 00 dev cdrom mnt cdrom udf iso9660 noauto owner kudzu ro 0 0 LABEL myfiles home myusername myfiles ext3 de faults 00 I can manually mount the filesystem or wait until I reboot I prefer to mount it now mount home myusername myfiles CONTENTS 138 If I did everything correctly the mount command will check etc fstab find the file type and LABEL and mount the file without a problem I can check with the mount command mount dev hdal on type ext3 rw proc on proc type proc rw dev hda2 on usr type ext3 rw dev hda4 on var type ext3 rw none on dev pts type devpts rw mode 0622 dev hdb1 on home myusername myfiles type ext3 rw It worked Creating Swap Space The steps for creating swap space are similar to those for creating any other file system One difference is the filesystem type under fdisk We ll use the second partition on the drive above for our example fdisk dev hdb The number of cylinders for this disk is set to 1653 There is nothing wro
2. Long form argu ments in Linux are preceded by two minus signs For example rm f CONTENTS 7 and rm force are the same command arguments the former short form the latter long form An option modifies the behavior of a command in some way or gives details in exactly how the command is to operate Some options are not preceded by anything Expression usually a character string which is used as input to the command Some are regular expressions using metacharacter strings which are used for string matching The general form for arguments following a command is command options expression filename s but the exact order required by each command should be found by referring to the documentation for the specific command What follows are the man pages from Linux followed by some simple usage examples Man Pages Historically UNIX systems have kept the User s Manual Programmers Manual and Administrator s Manual on line collectively refered to as manual pages or man pages Linux follows this tradition There is a move to replace the man pages with Texinfo info info will tell you more about Texinfo and so many of the GNU man pages have a statement similar to the following This documentation is no longer being maintained and may be inaccurate or incomplete The Texinfo documentation is now the authoritative source Man pages describe user commands system calls library functions configura tion file form
3. device dir mount fnrsvw t vfstype o options device dir CONTENTS 56 DESCRIPTION All files accessible in a Unix system are arranged in one big tree the file hierar chy rooted at These files can be spread out over several devices The mount command serves to attach the file system found on some device to the big file tree Conversely the umount 8 command will detach it again The standard form of the mount command is mount t type device dir This tells the kernel to attach the file system found on device which is of type type at the directory dir The previous contents if any and owner and mode of dir become invisible and as long as this file system remains mounted the pathname dir refers to the root of the file system on device Three forms of invocation do not actually mount anything mount h prints a help message mount V prints a version string and just mount t type lists all mounted file systems of type type see below The proc file system is not associated with a special device and when mounting it an arbitrary keyword such as proc can be used instead of a device specifi cation The customary choice none is less fortunate the error message none busy from umount can be confusing Most devices are indicated by a file name of a block special device like dev sdal but there are other possibilities For example in the case of an NFS mount device may look like knuth cwi nl dir
4. P pager Specify which pager to use This option overrides the MANPAGER environment variable which in turn overrides the PAGER variable By default man uses usr bin less is S section_list List is a colon separated list of manual sections to search This option overrides the MANSECT environment variable a By default man will exit after displaying the first manual page it finds Using this option forces man to display all the manual pages that match name not just the first c Reformat the source man page even when an up to date cat page exists This can be meaningful if the cat page was formatted for a screen with a different number of columns or if the preformatted page is corrupted d Don t actually display the man pages but do print gobs of debugging infor mation D Both display and print debugging info f Equivalent to whatis CONTENTS 51 h Print a one line help message and exit k Equivalent to apropos K Search for the specified string in all man pages Warning this is probably very slow It helps to specify a section Just to give a rough idea on my machine this takes about a minute per 500 man pages m system Specify an alternate set of man pages to search based on the system name given p string Specify the sequence of preprocessors to run before nroff or troff Not all installations will have a full set of preprocessors Some of the preproces sors and the letters used to designate them
5. G The G option suppresses all highlighting of strings found by search com mands hn Specifies a maximum number of lines to scroll back ward If it is nec essary to scroll backward more than n lines the screen is repainted in a forward direction instead If the terminal does not have the ability to scroll backward h0 is implied i Causes searches to ignore case that is uppercase and lowercase are consid ered identical This option is ignored if any uppercase letters appear in the search pattern in other words if a pattern contains uppercase letters then that search does not ignore case I Like i but searches ignore case even if the pattern contains uppercase letters jn Specifies a line on the screen where the target line is to be positioned A target line is the object of a text search tag search jump to a line number jump to a file percentage or jump to a marked position The screen line is specified by a number the top line on the screen is 1 the next is 2 and so on The number may be negative to specify a line relative to the bottom of the screen the bottom line on the screen is 1 the second to the bottom is 2 and so on If the j option is used searches begin at the line immediately after the target line For example if j4 is used the target line is the fourth line on the screen so searches begin at the fifth line on the screen CONTENTS 30 kfilename Causes less to open and interpret
6. System Startup and Initialization Running the System Why you shouldn t be root Most modern Linux distribution prompt you during the installation to create a user on the system with good reason The root user is all powerful on a Linux system With this power comes respon sibility Since Linux has not trashbin and no simple means to recover deleted files when you tell it to remove files it usually does so without hesitation and often without prompting you unless there is an error For the beginner the lack of response from the system can often be disconcerting If you are running as root it can be hazardous to your system Many system commands have recursive options as well as wild card arguments that can create havoc on your system if you are root If you run as a regular user you can still destroy a lot of data in your home directory but you usually don t have the proper ownership and permissions to do much damage to the system as a whole One of the reasons Linux is highly resistant to virus and worm infection is that most users on the system don t have root privileges and therefore can t propogate virus and worms to system files Operating as root would circumvent these protections and allow viruses and worms to spread through Linux systems much as they do in other operating systems Booting the System In this section we cover various methods for booting the system go into detail about the initialization s
7. s command is equivalent to specifying o from within less ppattern The p option on the command line is equivalent to specifying pattern that is it tells less to start at the first occurrence of pattern in the file Pprompt Provides a way to tailor the three prompt styles to your own pref erence This option would normally be put in the LESS environment variable rather than being typed in with each less command Such an option must either be the last option in the LESS variable or be termi nated by a dollar sign Ps followed by a string changes the default short prompt to that string Pm changes the medium m prompt PM changes the long M prompt Ph changes the prompt for the help screen P changes the message printed by the command All prompt strings consist of a sequence of letters and special escape sequences See the section on PROMPTS for more details CONTENTS 31 q Causes moderately quiet operation the terminal bell is not rung if an attempt is made to scroll past the end of the file or before the beginning of the file If the terminal has a visual bell it is used instead The bell will be rung on certain other errors such as typing an invalid character The default is to ring the terminal bell in all such cases Q Causes totally quiet operation the terminal bell is never rung r Causes raw control characters to be displayed The default is to display control charac
8. 35 36 37 38 39 AO Al 42 43 44 45 remounts the root filesystem in read write initializes LVM Logical Volume Management activates swaps writes a new mtab starts syslog runs depmd load sound modules load kernel modules start any configured raid devices initialize LVM again in case any are on the raid just started mount all other filesystems check quotas on newly mounted filesystems reread the network configuration and reset the hostname if necessary clean up var reset the console permissions clean up utmp delete stale locks turn on swap read etc rc serial and configure serial ports check for scsi tape drives and load the module for it load usb storage check for and load firewire load ide scsi for things like ide CDR burners and DVD R run hdparm for ide drives generate a header that defines the boot kernel adjust symlinks for System map file dumps syslog messages to a file var log dmesg creates a crash indicator flag to warn on crashes CONTENTS 126 etc init d functions re EN SOX OE HR eR 10 11 12 13 14 15 16 17 18 19 sets the umask sets up a default search path configures the screen width reads sources etc sysconfig init which may be specific to Red Hat checkpid function to get the pid process id of a program daemon functions to start a program killproc function to stop a program pidfileofproc function to find the pid of a program
9. BU GS On BSD systems du reports sizes that are half the correct values for files that are NFS mounted from HP UX systems On HP UX systems it reports sizes that are twice the correct values for files that are NFS mounted from BSD systems This is due to a flaw in HP UX it also affects the HP UX du program EXAMPLES du a 1 thisfile 1 thatfile 0 thosefiles 0 onefile 0 twofile 0 threefile 0 fourfile 0 firstfile 0 lastfile 3 du s 3 CONTENTS 21 head NAME head output the first part of files SYNOPSIS head c N bkm n N qv bytes N bkm lines N quiet silent verbose help version file head Nbcklmqy file DESCRIPTION This documentation is no longer being maintained and may be inaccurate or incomplete The Texinfo documentation is now the authoritative source This manual page documents the GNU version of head head prints the first part 10 lines by default of each given file it reads from standard input if no files are given or when a filename of is encountered If more than one file is given it prints a header consisting of the file s name enclosed in gt and lt before the output for each file OPTIONS head accepts two option formats the new one in which numbers are arguments to the option letters and the old one in which the number precedes any option letters c N bytes N Print first N bytes N is a no
10. chmod 444 fourfile r r r 1 root root 0 Mar 26 19 22 fourfile chmod 555 lastfile r xr xr x 1 root root 0 Mar 26 19 22 lastfile chmod 666 onefile rw rw rw 1 root root 0 Mar 26 19 22 onefile chmod 777 thatfile rwxrwxrwx 1 root root 0 Mar 26 19 22 thatfile chmod 400 thisfile r 1 root root 29 Mar 26 19 23 thisfile chmod 500 thosefiles r x 1 root root 0 Mar 26 19 22 thosefiles chmod 600 threefile rW 1 root root 0 Mar 26 19 22 threefile chmod 700 twofile rwx 1 root root 0 Mar 26 19 22 twofile chmod 1400 firstfile r T 1 root root 0 Mar 26 19 22 firstfile chmod 2400 fourfile r S 1 root root 0 Mar 26 19 22 fourfile chmod 3400 lastfile r S T 1 root root 0 Mar 26 19 22 lastfile chown NAME chown change the user and group ownership of files SYNOPSIS chown Rcfv recursive changes help version silent quiet verbose user group file CONTENTS 14 DESCRIPTION This documentation is no longer being maintained and may be inaccurate or incomplete The Texinfo documentation is now the authoritative source This manual page documents the GNU version of chown chown changes the user and or group ownership of each given file according to its first non option argument which is interpreted as follows If only a user name or numeric user ID is given that user is made the owner of each given file and the files group is n
11. m Replaced by the total number of input files pX Replaced by the percent into the current input file The line used is determined by the X as with the b option s Same as B t Causes any trailing spaces to be removed Usually used at the end of the string but may appear anywhere x Replaced by the name of the next input file in the list If any item is unknown for example the file size if input is a pipe a question mark is printed instead The format of the prompt string can be changed de pending on certain conditions A question mark followed by a single character acts like an IF depending on the following character a condition is evaluated If the condition is true any characters following the question mark and condi tion character up to a period are included in the prompt If the condition is false such characters are not included A colon appearing between the question mark and the period can be used to establish an ELSE any characters be tween the colon and the period are included in the string if and only if the IF condition is false Condition characters which follow a question mark may be a True if any characters have been included in the prompt so far bX True if the byte offset of the specified line is known CONTENTS 39 B True if the size of current input file is known e True if at end of file f True if there is an input filename that is if input is not a pipe 1
12. the original filename as entered by the user and the name of the replacement file To set up an input postprocessor set the LESSCLOSE environment variable to a command line which will invoke your input postprocessor It may include two occurrences of the string s the first is replaced with the original name of the file and the second with the name of the replacement file which was output by LESSOPEN For example on many Unix systems these two scripts will allow you to keep files in compressed format but still let less view them directly lessopen sh bin sh case 1 in Z uncompress c 1 gt tmp less 2 gt dev null if s tmp less then echo tmp less else rm f tmp less fi esac lessclose sh bin sh rm 2 To use these scripts put them both where they can be executed and set LESSOPEN lessopen sh s and LESSCLOSE lessclose sh s s More complex LESSOPEN and LESSCLOSE scripts may be written to accept other types of compressed files and so on It is also possible to set up an input preprocessor to pipe the file data directly to less rather than putting the data into a replacement file This avoids the need to decompress the entire file before starting to view it An input preprocessor that works this way is called an input pipe An input pipe instead of writing the name of a replacement file on its standard output writes the entire contents of the replacement file
13. CONTENTS 27 string value such as P or t a new value may be entered after the option letter If no new value is entered a message describing the current setting is printed and nothing is changed Followed by one of the command line option letters see below this will reset the option to its default setting and print a message describing the new setting The X command does the same thing as X on the command line This does not work for string valued options Followed by one of the command line option letters see below this will reset the option to the opposite of its default setting and print a message describing the new setting The X command does the same thing as X on the command line This does not work for numeric or string valued options Underscore Followed by one of the command line option letters see be low this will print a message describing the current setting of that option The setting of the option is not changed cmd Causes the specified cmd to be executed each time a new file is examined For example G causes less to initially display each file starting at the end rather than the beginning V Prints the version number of less being run q or Q or q or Q or ZZ Exits less The following four commands may or may not be valid depending on your particular installation v Invokes an editor to edit the current file being viewed The editor is taken fro
14. Jim Sack jsack dornfeld com Deleting and Disabling Accounts Jim Sack jsack dornfeld com Modifying User Accounts Jim Sack jsack dornfeld com Managing File Systems As a system administrator you can create modify and delete filesystems Main taining a filesystem is often not needed in a good filesystem 130 CONTENTS 131 Filesystem Basics The most popular filesystem based on the of installations worldwide is the FAT FAT32 File Allocation Table filesystem used by Microsoft Windows it is where the files are being stored and retrieved by the operating system and the user If you are using Windows and you partitioned your harddrive into several or you have more than one harddrive you will see C D E drives and so on These are treated as different drives and at the same time different filesystems For instance D can be a CD ROM that contains StarCraft a game your E drive might be a Zip drive A CD ROM uses the ISO9660 filesystem and can be read from Windows A Zip diskette can have any filesystem and once you format it in Windows it will have FAT filesystem your C drive is also filesystem using FAT technology In other words a filesystem is how a physical media CD ROM Zip Superdisk DVD Harddrive is organized to store files The operating system must support the particular filesystem in order to access data Windows does not support Ext2 filesystem used by Linux but supports CIFS Common Intern
15. OPTIONS a all List all files in directories including all files that start with b escape Quote non graphic characters in file names using alphabetic and octal backslash sequences like those used in C c time ctime time status Sort directory contents according to the files status change time instead of the modification time If the long listing for mat is being used print the status change time instead of the modification time d directory List directories like other files rather than listing their contents f Do not sort directory contents list them in what ever order they are stored on the disk The same as enabling a and U and disabling l s and t full time List times in full rather than using the standard abbreviation heuris tics g Ignored for Unix compatibility i inode Print the index number of each file to the left of the file name k kilobytes If file sizes are being listed print them in kilobytes This overrides the environment variable POSIXLY_CORRECT l format long format verbose In addition to the name of each file print the file type permissions number of hard links owner name group name size in bytes and timestamp the modification time unless other times are selected For files with a time that is more than 6 months old or more than 1 hour into the future the times tamp contains the year instead of the time of day m format commas List file
16. The most visible parts of the Init facility are sbin init and etc inittab program and it s configfuration data file etc init d scripts for starting and stoping processes etc re d scripts and subdirectories rcl d rc2 d rc6 d etc sysconfig additional sources and subdirectory network scripts On a RedHat 9 0 system ls R etc sysconfig etc init d etc re d we P reports 671 entries Inittab During boot the kernel locates sbin init Init is the parent of all processes Its primary role is to create processes from a script stored in the file etc inittab The man page for inittab describes syntax of inittab lines id runlevels action process runlevels 0 6 A C or empty 0 amp 6 are used for shutting the machine down 1 is reserved for single user mode 2 5 are available to define custom operating configurations A C are used for ondemand actions not a runlevel change action values of particular interest there are others see man inittab initdefault defines the default runlevel eg id 3 initdefault sysinit always processed always before anything else eg si sysinit etc rc d re sysinit once used mainly for any level processes eg ud once sbin update starts bdflush CONTENTS 124 wait used for the primary runlevel specife action script eg 13 3 wait etc re d rce3 respawn used to provide login gettys for virtual consoles serial co
17. and lilo conf 5 LILO is a versatile boot loader for Linux It does not depend upon a specific file system can boot Linux images from a floppy disk and from hard disks and act as a boot manager for other operating systems Up to sixteen different images can be selcected at boot time Various paramters can be set independently for each kernel LILO can even be used as the master boot record What is lilo LILO is a collection of several programs and other files The map installer is the program you run under Linux to put all files belong ing to LILO at the appropriate places and to record information about the location of data needed at boot time This program normally resides in sbin lilo It has to be run to refresh that information whenever any part of the system that LILO knows about changes e g after installing a new kernel Various files contain data LILO needs at boot time e g the boot loader Those files normally reside in boot The most important files are the boot loader see below and the map file boot map where the map installer records the location of the kernel s Another important file is the configuration file which is normally called etc lilo conf The boot loader is the part of LILO that is loaded by the BIOS and that loads kernels or the boot sectors of other operating systems It also provides a simple command line interface to interactively select the item to boot and to add boot options LI
18. and will pause after any line that contains a form feed The l option will prevent this behavior f Causes more to count logical rather than screen lines i e long lines are not folded p Do not scroll Instead clear the whole screen and then display the text c Do not scroll Instead paint each screen from the top clearing the remainder of each line as it is displayed s Squeeze multiple blank lines into one u Suppress underlining The option specifies a string that will be searched for before each file is displayed num Start at line number num CONTENTS 54 COMMANDS Interactive commands for more are based on vi 1 Some commands may be preceded by a decimal number called k in the descriptions below In the fol lowing descriptions X means control X h or Help display a summary of these commands If you forget all the other commands remember this one SPACE Display next k lines of text Defaults to current screen size z Display next k lines of text Defaults to current screen size Argument becomes new default RETURN Display next k lines of text Defaults to 1 Argument becomes new default dor D Scroll k lines Default is current scroll size initially 11 Argument becomes new default q or Q or INTERRUPT Exit s Skip forward k lines of text Defaults to 1 f Skip forward k screenfuls of text Defaults to 1 b or B Skip backwards k screenfuls of text Defaults to 1 Go to place
19. foreground process so called because it is in the foreground of your attention Normally each command or pipleline of commands is in the foreground meaning they run and you wait for them to return their results It is also possible to execute programs as background processes This means that you can execute the program while still having your shell available for running other commands The shell provides the amp ampersand operator to allow you to run commands in the background You simply add it to the end of a command line updatedb amp 1 865 The command has not completed It is still running but you can use your system for other things while the backgrounded command proceeds updatedb updates the locate database When you run a command with the amp you get the shell prompt immediately and are able to enter further commands even though the process you created is still running The shell will return a process id PID so you can refer to that process and then return your prompt for another command Output will still come to your screen because you did not redirect it This can cause some confusion since the output of the backgrounded process will be be mixed with the output of whatever command you are currently executing in the foreground Obviously the proper choice it to redirect the output of a background process to a file You can also redirect the error output so that it doesn t pop up on your screen
20. ignore zeros ignore failed read k keep old files K starting file F l one file system L tape length N m modification time M multi volume N after date DATE newer DATE o old archive portability O to stdout p same permissions preserve permissions P absolute paths preserve R record number remove files s same order preserve order same owner S sparse T files from F null totals v ver bose V label NAME version w interactive confirmation W verify exclude FILE X exclude from FILE Z compress uncompress z gzip ungzip use compress program PROG block compress 0 7 lmh filenamel filename 2 filenameN directory1 directory2 directoryN DESCRIPTION This manual page documents the GNU version of tar an archiving program designed to store and extract files from an archive file known as a tarfile A tarfile may be made on a tape drive however it is also common to write a tarfile to a normal file The first argument to tar must be one of the options Acdrtux followed by any optional functions The final arguments to tar are the names of the files or directories which should be archived The use of a directory name always implies that the subdirectories below should be included in the archive FUNCTION LETTERS O
21. is 8 I ignore pattern Do not list files whose names match the shell pat tern pattern unless they are given on the command line As in the shell an initial in a file name does not match a wildcard at the start of pat tern color colour color yes colour yes Colorize the names of files depending on the type of file See DISPLAY COLORIZATION below color tty colour tty Same as color but only if standard output is a ter minal This is very useful for shell scripts and command aliases especially if your favorite pager does not support color control codes color no colour no Disables colorization This is the default Provided to override a previous color option help Print a usage message on standard output and exit successfully version Print version information on standard output then exit successfully DISPLAY COLORIZATION When using the color option this version of ls will colorize the file names printed according to the name and type of file By default this colorization is by type only and the codes used are ISO 6429 ANSI compliant You can override the default colors by defining the environment variable LS_COLORS or LS_COLOURS The format of this variable is reminiscent of the termcap 5 file format a colon separated list of expressions of the form xx string where xx is a two character variable name The variables with their associated defaults are no 0 Normal
22. lt Go to line N in the file default 1 beginning of file Warn ing this may be slow if N is large G or gt or ESC gt Go to line N in the file default the end of the file Warn ing this may be slow if N is large or if N is not specified and standard input rather than a file is being read p or Go toa position N percent into the file N should be between 0 and 100 If a left curly bracket appears in the top line displayed on the screen the command will go to the matching right curly bracket The matching right curly bracket is positioned on the bottom line of the screen If there is more than one left curly bracket on the top line a number N may be used to specify the N th bracket on the line If a right curly bracket appears in the bottom line displayed on the screen the command will go to the matching left curly bracket The matching left curly bracket is positioned on the top line of the screen If there is more than one right curly bracket on the top line a number N may be used to specify the N th bracket on the line Like but applies to parentheses rather than curly brackets Like but applies to parentheses rather than curly brackets Like but applies to square brackets rather than curly brackets Like but applies to square brackets rather than curly brackets ESC F Followed by two characters acts like but uses the two characters as open and close brackets respectively For example
23. only the final screenful is displayed w Like ESC v but if N is specified it becomes the new window size y or Y or P or k or K Scroll backward N lines default 1 The entire N lines are displayed even if N is more than the screen size Warning some systems use Y as a special job control character u or U Scroll backward N lines default one half of the screen size If N is specified it becomes the new default for subsequent d and u commands ESC gt or RIGHTARROW Scroll horizontally right N characters default 8 This behaves best if you also set the S option chop lines Note that if you wish to enter a number N you must use ESC not RIGHTARROW because the arrow is taken to be a line editing command see the LINE EDITING section ESC lt or LEFTARROW Scroll horizontally left N characters default 8 ror Ror L Repaint the screen R Repaint the screen discarding any buffered input Useful if the file is chang ing while it is being viewed u or U Scroll backward N lines default one half of the screen size If N is specified it becomes the new default for subsequent d and u commands CONTENTS 24 F Scroll forward and keep trying to read when the end of file is reached Nor mally this command would be used when already at the end of the file It is a way to monitor the tail of a file which is growing while it is being viewed The behavior is similar to the tail f command g or lt or ESC
24. 2630655 86954 2412169 3 k mount k o bsddf df k umount k Filesystem 1024 blocks Used Available Capacity Mounted on dev sda6 2543714 13 2412169 0 k Note that this example shows that one can add command line options to the options given in etc fstab check check normal check strict Set checking level When at least one of these options is set and check normal is set by default the inodes and blocks bitmaps are checked upon mount which can take half a minute or so on a big disk With strict checking block deallocation checks that the block to free is in the data zone check none nocheck No checking is done debug Print debugging info upon each re mount errors continue errors remount ro errors panic Define the behav ior when an error is encountered Either ignore errors and just mark the file system erroneous and continue or remount the file system read only or panic and halt the system The default is set in the filesystem superblock and can be changed using tune2fs 8 grpid or bsdgroups nogrpid or sysvgroups These options define what group id a newly created file gets When grpid is set it takes the group id of the directory in which it is created other wise the default it takes the fsgid of the cur rent process unless the directory has the setgid bit set in which case it takes the gid from the parent directory and also gets the setgid bit set if it is a directory itself CONTENTS 62 r
25. If a pattern does contain metacharacters locate only displays file names that match the pattern exactly As a result patterns that contain metacharacters should usually begin with a and will most often end with one as well The exceptions are patterns that are intended to explicitly match the beginning or end of a file name The file name databases contain lists of files that were on the system when the databases were last updated The system administrator can choose the file name of the default database the frequency with which the databases are updated and the directories for which they contain entries see updatedb 1L OPTIONS d path database path Instead of searching the default file name database search the file name databases in path which is a colon separated list of database file names You can also use the environment variable LOCATE_PATH to set the list of database files to search The option over rides the environment variable if both are used The file name database format changed starting with GNU find and locate version 4 0 to allow machines with different byte orderings to share the databases This ver sion of locate can automatically recognize and read databases produced for older versions of GNU locate or Unix versions of locate or find CONTENTS 44 help Print a summary of the options to locate and exit version Print the version number of locate and exit ENVIRONMENT LOCATE_PATH Colon se
26. Page Cursor Keys Cut Copy and Paste Cutting Text Uncutting Text Marking Text Where am I Current position Spell Checker Jed Text and Document Processing Printing 177 178 CONTENTS 179 The X Window System X Concepts Hardware Requirements Installing XFree86 Configuring XFree86 Xconfigurator XF86Setup xf86config Running XFree86 Running Into Trouble Customizing Your X Environment Window Managers FVWM FVWM95 AfterStep Window Maker Enlightenment Enlightenment has to be one of the best looking Window managers for the X windows system What it lacks in power it makes up in its wownderful appear CONTENTS 180 ance Recently released DR 15 is fast configurable and worth downloading Most window managers are based on something else FVWM95 windows95 Window Maker NeXT AmiWM AmigaOS Enlightenment is totally different than any of those It is not based on any previous OS or anything like that Mainly coded by two people Carsten Haitzler rasterman and Geoff Harrison mandrake Both under the age of 30 or so they want us to think It is themeable to the point of unrecognition Some themes are made to mimic operating systems or even other window managers Homepage http www enlightenment org Main Themes Page http e themes org KDE Books and Bibliography Unix The Complete Reference System V Release 3 Stephen Coffin Osborne McGraw Hill ISBN 0 07 881299 2 Introducing
27. The file etc fstab see fstab 5 may contain lines describing what devices are usually mounted where using which options This file is used in three ways e The command mount a t type usually given in a bootscript causes all file systems mentioned in fstab of the proper type to be mounted as indicated except for those whose line contains the noauto keyword Adding the F option will make mount fork so that the filesystems are mounted simultaneously e When mounting a file system mentioned in fstab it suffices to give only the device or only the mount point e Normally only the superuser can mount file systems However when fstab contains the user option on a line then anybody can mount the corresponding system Thus given a line dev cdrom cd iso9660 ro user noauto unhide any user can mount the iso9660 file system found on his CDROM using the command CONTENTS 57 mount dev cdrom or mount cd For more details see fstab 5 The programs mount and umount maintain a list of currently mounted file systems in the file etc mtab If no arguments are given to mount this list is printed When the proc filesystem is mounted say at proc the files etc mtab and proc mounts have very similar contents The former has somewhat more information such as the mount options used but is not necessarily up to date cf the n option below It is possible to replace etc mtab by a symbolic link to proc mounts but some inf
28. also have the Print Server Name IP address Printer name Printer User and Printer password For NCP printers also required are Printer Server Name Printer User and Printer Password There are excellent on line help and troubleshooting guides available from printtool Network Configuration Beside getting to the Network configuration tool from the control panel you can also call it by itself in the following manner su Password export DISPLAY 0 0 netcfg From this gui utility you can configure hostname Domain and the locations of nameservers This is all done within the first screen that apears when you start netcfg To enable the ability of you local machine to share data with other systems on your network when you don t have named running you must enter the names and addresses of other machines on your network The hosts tab takes you to that section Here you can add the ip addresses hostnames and nick names for your other networked computers You can edit interface configurations from the Interfaces tab To add or delete ethernet devices set IP addresses click on the tab and then choose from Add Edit Clone Alias Remove Activate and Deactivate Routing can also be configured in the Network Convigurator When you click on the Routing tab you will see places to turn on and off packet forwarding masquerading add default routes and add other static routes you may need for your configuration CONT
29. are compiled in and for English no catalog is required Note that programs like col 1 called by man also use e g LC_CTYPE PATH PATH is used in the construction of the default search path for man pages SYSTEM SYSTEM is used to get the default alternate system name for use with the m option SEE ALSO apropos 1 whatis 1 less 1 groff 1 BUGS The t option only works if a troff like program is installed If you see blinking 255 or lt AD gt instead of hyphens put LESS CHARSET latin1 in your environment CONTENTS 53 EXAMPLES more NAME more file perusal filter for crt viewing SYNOPSIS more dlfpcsu num pattern linenum file DESCRIPTION More is a filter for paging through text one screenful at a time This version is especially primitive Users should realize that less 1 provides more 1 emula tion and extensive enhancements OPTIONS Command line options are described below Options are also taken from the environment variable MORE make sure to precede them with a dash but command line options will override them num This option specifies an integer which is the screen size in lines d more will prompt the user with the message Press space to continue q to quit and will display Press h for instructions instead of ringing the bell when an illegal key is pressed l1 more usually treats L form feed as a special character
30. at 06 00 apr 04 at pppoff at lt EOT gt EOT the control key then the d key or d To send yourself a reminder to not burn dinner in 15 minutes use the next sequence at now 15 minutes at echo Dinner is burning mail yourusername at lt EOT gt You can use the now time unit to run a command from now until that amount of time Where time unit could be minutes hours days or weeks You can also use tomorrow or the British time frame teatime See man at for more information CONTENTS 166 Managing System Logs Managing Print Services Checking Printer Hardware Controlling Printer Services with Ipc Printer Services Maintenance Printer System Troubleshooting Red Hat printtool What to Do in an Emergency Repairing Filesystems Accessing Damaged Files Restoring Files from Backup Editors Text Tools and Printing Editing with vi vi short for visual and pronounced vee eye is a screen oriented editing pro gram used by many Unix users and in particular programmers Regular users of vi find it a very convenient editing program but it does take learning and at first that will look unintuitive Hopefully this guide is but one step towards hopping over that hurdle Basic editing Help How do I get out of this confounded program q vi has possibly one of the most unintuitive interfaces and for the user who s used to graphical editors the first thing they want to do is to quit and re
31. can work against you or you can use it to your advantage CONTENTS 94 File and Directory Ownership and Permissions Because Linux is a multiuser sytem files can be created by individual users and are then owned by by that user until they either delete them or give them to another user Each user belongs to one or more groups and can share files with other members of that group Permission determine how users on the system can use files and directories read permissions determine who is able to look at a file write permissions determine who is able to change a file execute permissions detrmine who is able to execute a file or run the program associated with the file On occassion you will need to change these attributes For example when you write a shell or perl script you must change the permissions to make the script executable Write and execute permissions for directories go together Generally if you allow users to write files to a directory you also allow them to remove files from that directory There exists a mechanism to allow users to only delete files from a directory that they wrote See discussion below of the save program text attribute on directories To facilitate file sharing Linux has three levels of permission user group and others The user is generally the person who created the file The group is determined by the etc group file and is often created by an administrator to create colaborative g
32. characters as P help Print a usage message and exit with a status code indicating success version Print version information on standard output then exit EXAMPLES cat thisfile This is the text in thisfile cd NAME cd change working directory CONTENTS 11 SYNOPSIS cd dirName DESCRIPTION Change the current working directory to dirName or to the home directory as specified in the HOME environment variable if dirName is not given Returns an empty string KEYWORDS working directory EXAMPLES cd usr local pwd usr local cd pwd home myhome chmod NAME chmod changes the permissions of a file or directory SYNOPSIS chmod Refv recursive changes silent quiet verbose help version mode file DESCRIPTION This documentation is no longer being maintained and may be inaccurate or incomplete The Texinfo documentation is now the authoritative source This manual page documents the GNU version of chmod chmod changes the per missions of each given file according to mode which can be either a symbolic representation of changes to make or an octal number representing the bit pattern for the new permissions The format of a symbolic mode is ugoa rwxXs tugo Multiple symbolic operations can be given separated CONTENTS 12 by commas A combination of the letters ugoa controls which users access to the fil
33. decompression even if the file has multiple links or the corresponding file already exists or if the compressed data is read from or written to a terminal If the input data is not in a format recog nized by gzip and if the option stdout is also given copy the input data without change to the standard ouput let zcat behave as cat If f is not given and when not running in the background gzip prompts to verify whether an existing file should be overwritten h help Display a help screen and quit l list For each compressed file list the following fields e compressed size e size of the compressed file e uncompressed size size of the uncompressed file e ratio compression ratio 0 0 if unknown e uncompressed_name name of the uncompressed file The uncompressed size is given as 1 for files not in gzip format such as com pressed Z files To get the uncompressed size for such a file you can use zcat file Z we c In combination with the verbose option the following fields are also displayed e method compression method e cre the 32 bit CRC of the uncompressed data e date amp time time stamp for the uncompressed file CONTENTS 154 The compression methods currently supported are deflate compress Izh SCO compress H and pack The crc is given as ffffffff for a file not in gzip format With name the uncompressed name date and time are those stored within the compress file if present With ve
34. dependencies before removing the package Querying with RPM You can query RPMs for information about the packages and you can query the rpm database about files on the system The general form of an rpm query is rpm q query options Some of the more popular forms are To find out the contents of a package or which files and where they were put on the system rpm qpl lt package_file gt CONTENTS 148 To query a file to find out what package it came from rpm qf lt file name gt There are many options for querying packages and the database a Query all installed packages whatrequires lt capability gt Query all packages that requires lt capability gt for proper functioning whatprovides lt virtual gt Query all packages that provide the lt virtual gt ca pability f lt file gt Query package owning lt file gt requiredby lt package gt Query all of the package which contain triggers scripts that are triggered by lt package gt p lt package_file gt Query an uninstalled package lt package_file gt The lt pack age_file gt may be specified as an ftp style URL in which case the package header will be down loaded and queried See FTP OPTIONS for information on RPM s built in ftp support Information selection options i Display package information including name ver sion and description This uses the queryformat if one was specified R List packages this one depends on
35. drive I need to create a filesystem fdisk I decide that I don t want to use the entire drive so I m going to partition it into 4 equal 2 5Gb primary partitions They will become hdb1 hdb2 hdb3 and hdb4 I will use fdisk to partiton fdisk dev hdb The number of cylinders for this disk is set to 1653 There is nothing wrong with that but this is larger than 1024 and could in certain setups cause problems with 1 software that runs at boot time e g old versions of LILO 2 booting and partitioning software from other OSs e g DOS FDISK OS 2 FDISK Disk dev hdb 255 heads 63 sectors 1653 cylinders Units cylinders of 16065 512 bytes Command m for help n Command action e extended p primary partition 1 4 p Partition number 1 4 1 First cylinder 1 621 default 1 Using default value 1 Last cylinder or size or sizeM or sizeK 1 621 default 621 2 5M Command m for help n Command action e extended CONTENTS 136 p primary partition 1 4 p Partition number 1 4 2 First cylinder 413 1653 default 413 Using default value of 413 Last cylinder or size or sizeM or sizeK 413 1653 default 1653 2 5Gb Command m for help w The partition table has been altered Calling ioctl to re read partition table I continue on in the same manner creating the other two primary partitions hdb3 and hdb4 When I have finished the partition table looks like this Disk dev hdb 255 he
36. e g MS DOS disk parameters The first 446 0x1BE bytes of the MBR are used by the loader program They are followed by the partition table with a length of 64 0x40 bytes The last two bytes contain a magic number that is sometimes used to verify that a given sector really is a boot sector LILO in the MBR This is a safe LILO setup LILO is booted by the DOS MBR No other boot sectors have to be touched If the other OS or one of them if there are several other operating systems being used should be booted without using LILO the other partition has to be marked active with fdisk or activate Installation e install LILO with its boot sector on the Linux partition e use fdisk or activate to make that partition active e reboot When you choose LILO as your boot loader during the installation of Linux and you choose to install it into the MBR this is essentially what the installer does CONTENTS 106 Bios Limitations The most common BIOS restrictions that affect LILO are the limitation to two hard disks and the inability to access more than 1024 cylinders per disk LILO can detect both conditions but in order to work around the underlying problems manual intervention is necessary The drive limit does not exist in every BIOS Some modern motherboards and disk controllers are equipped with a BIOS that supports more typically four disk drives When attempting to access the third fourth etc drive LILO print
37. file in that directory can delete it user u permissions that the user that is owner of the file currently has group g permissions that the files group has for it others o permissions that others not user or group of the file have for it The numeric mode is derived by adding up the bites with values of 4 r 2 w and 1 x Omitted digits are assumed to be leading zeros Difficult unless you know binary arithmetic Starting from left to right each mode is represented as follows 4000 is u s 2000 is g s 1000 is t 400 is r for user 200 is w for user 100 is x for user 40 is r for group 20 is w for group 10 is x for group 4 is r for other CONTENTS 98 2 is w for other 1 is x for other So by adding up these number we can set the mode for a file with a numerical value Here s a simple example root localhost Is l thisfile rw rw r 1 joe joe 29 Mar 26 19 23 thisfile root localhost chmod 666 thisfile rw rw rw 1 sam sam 29 Mar 26 19 23 thisfile The octal representations may seem difficult at first Once you understand the octal representations you may find them the easiest to use Here are some of the common one 644 is rw r r the owner can read and write everyone else can read only 755 is rwxr xr x the owner card read write and execute everybody else can read or execute it For a directory this is equivlent to 644 711 is rwx x x the owner can read write and execute every
38. for configurations of other parts of the system lib is where shared libraries are These are the libraries that are shared among applications running under Linux These libraries are shared among running applications to reduce program overhead by only loading those functions needed at run time And by making one copy of the libraries available to multiple running programs memory is conserved home is where the users home directories are located For example the home directory for user joe would be located in home joe A user can abbreviate the reference to their home directory with the tilde For example joe could abbreviate a file in his home directory by refering to it by filename If joe had created a bin directory in his home directory he could reach it by the command cd bin mnt is by convention and usage the directory where temporary filesystems would be mounted opt is a commonly the directory where commercial appli cations will be installed proc is a virtualized file system If you were able to look at the filesystem on a Linux system when it wasn t running you would find nothing in the directory The files and directories under proc are a model of what is going on within the running kernel Under special circumstances files and instructions can be echoed to the proc filesystem to make changes to the running kernel root is the home directory of the super user root The root user s environment is set
39. from gt in the line with lt to gt lt from gt and lt to gt can both be normal plain text e g s 1998 1999 replaces the first 1998 in the line to 1999 but lt from gt is more precisely described as a regular expression which again is outside the scope of the document s lt from gt lt to gt g As above but replaces all instances and not just the first I m looking for a needle in a haystack help lt pattern gt This will search from the current cursor position through to the end of the buffer for lt pattern gt which is a regular expression again in most cases you can just type in plain text lt pattern gt Searches backwards from the cursor position to the beginning of the buffer for the pattern CONTENTS 171 But some of these commands only affect one character Most of the commands above that do not have a colon can have a number typed before it for repeating the action Examples 8w advances the cursor 8 words forward 4s replaces the 4 characters from the cursor onwards 3i inserts whatever text you type 3 times Useful if you need to repeat something many times 10dd deletes 10 lines from the current line down Remember the commands with colons do not behave that way So how do I repeat colon commands This section is slightly more technical you may wish to skip it The colon commands or more precisely called ex commands because they are used in the ex 1 editor work with th
40. hour clock conifguration You can also call the application directly CONTENTS 142 without the control panel by doing the following su Password export DISPLAY 0 0 timetool Printer Configuration Printer configuration on a Linux system can be quite challenging Fortunately Red Hat has recognized this and has integrated a set of print filters manageable through this interface that make it much simpler to produce high quality output even from older inkjet and dot matrix printers su Password export DISPLAY 0 0 printtool Or you can call it from the standard control panel by clicking on the printer icon in the box Printtool allows you to control print queues and four types of printers LOCAL printers are attached to the printer port of the local machine REMOTE printers are attached to antoher machine which has an Ipd daemon running SMB printers are attached to an SMB or Windows or a samba server NCP printers are attached to a NCP Use this to print on a machine running Netware mars_nwe software After a printer has been chosen you must choose the printer queue name the spool directory and file limit or maximum print job accepted for this printer For LOCAL printers you must also choose the printer device and the Input Filter based upon what brand an model printer you have For REMOTE printers you must also have the remote hostname and print CONTENTS 143 queue name For SMB printers you much
41. human and accepted by a computer in such a manner as to make the human feel as if he is in control A command in Linux is a sequence of words non blank characters separated by spaces blanks The entire command is terminated by the newline character Enter or Return The first word is the command the remaining words are arguments to the command Since spaces are used to separate arguments the arguments themselves must not contain spaces If for some reason you have to have an argument containing a space ie a filename or directory name containing a space the argument should be surrounded by double quotes or with single quotes or apostrophes Do not use the grave accent for this purpose Apostrophe and grave are not the same character Make sure you understand which is which Arguments to Commands In general arguments to Linux system commands are one of three things Fil name the name of a file which the command is to act upon Filenames can consist of almost any character In practice though most file names consist of only letters A Z a z numbers 0 9 and some other characters like underscore _ period and minus sign Linux is case sensitive so Linux and LINUX would be different filenames There are special meta characters or wild card char acters for file name matching You can use a shorthand notation for working on groups of files at a time Option this is a literal often preceded by a minus sign
42. is available The search path for kernel address to symbol resolution is e PS_SYSTEM_MAP e boot System map uname r e boot System map lib modules uname CONTENTS 74 e r System map etc psdatabase boot psdatabase uname r boot psdatabase lib modules uname r psdatabase NOTES The member used_math of task_struct is not shown since crt0 s checks to see if math is present This causes the math flag to be set for all processes and so it is worthless Programs swapped out to disk will be shown without command line arguments and unless the c option is given in parentheses CPU shows the cputime realtime percentage It will not add up to 100 unless you are lucky It is time used divided by the time the process has been running The SIZE and RSS fields don t count the page tables and the task_struct of a proc this is at least 12k of memory that is always resident SIZE is the virtual size of the proc code data stack To perform the device number to name mapping ps maintains a file called etc psdevtab updated whenever dev becomes newer and permissions al low update If permissions do not allow update every invokation of ps requires a stat 2 of every file in the dev directory If dev entries change often on your system you should run ps as root often Imay add a fallback file under HOME under force of popular demand AUTHOR ps was originally wr
43. knowledge of the system to interpret since many of the configura tion files are changed immediately after an install Files that were not installed from the package for example documentation files excluded on installation using the excludedocs option will be silently ignored The format of the output is a string of 8 characters a possible c denoting a configuration file and then the file name Each of the 8 characters denotes the result of a comparison of one attribute of the file to the value of that attribute recorded in the RPM database A single period means the test passed The following characters denote failure of certain tests 5 MD5 sum S File size L Symlink T Mtime D Device U User G Group M Mode includes permissions and file type Signature Checking RPMs RPMs can be produced with PGP signatures All RPMs built by Red Hat for example are signed with Red Hat s PGP signature This helps to insure the integrity and origin of the package To check the signature of an RPM use this command rpm checksig lt package_file gt CONTENTS 150 Other RPM Options and Resources You may want to learn how to build your own RPMs sign them with your PGP signature rebuild your RPM database or install packages throught the FTP options to RPM Since this document is intended for beginning Linux users we will not go into those options here It s good to know that these options are all avaialbe to you He
44. now the authoritative source This manual page documents the GNU version of pwd pwd prints the fully resolved name of the current directory That is all components of the printed name will be actual directory names none will be symbolic links Note that most Unix shells provide a built in pwd command with similar func tionality so the unadorned interactive pwd command will usually execute the built in version and not this one OPTIONS help Print a usage message on standard output and exit successfully version Print version information on standard output then exit successfully EXAMPLES pwd home root mkdir NAME mkdir make directories CONTENTS 9 SYNOPSIS mkdir p m mode parents mode mode help version dir DESCRIPTION This documentation is no longer being maintained and may be inaccurate or incomplete The Texinfo documentation is now the authoritative source This manual page documents the GNU version of mkdir mkdir creates a directory with each given name By default the mode of created directories is 0777 minus the bits set in the umask OPTIONS m mode mode Set the mode of created directories to mode which is symbolic as in chmod and uses the default mode as the point of departure p parents Ensure that each given directory exists Create any missing parent directories for each argument Parent directories default to the umask modified by u wx Do n
45. of the system operator and the software developer In Linux and other Unix like operating systems the filesystem design has been agreed upon by consensus over time This is important in a system designed to be multi user Lack of an agreed upon standard for file placement would make the sharing of resources difficult if not impossible So a consensus has built over time and we see these agreed upon attributes on Linux systems Understanding some of the basic file concepts on a Linux system is one of the keys to understanding how to make the best uses of it One concept that is fundamental to understanding Linux is that to the system everything is a file The tape drive is a file the keboard mouse and monitor are files the serial port is a file Files in Linux have three important features or attributes standard in standard out and error The concept is deceptively simple and some would even say elegant By creating simple files that have only a few predictable actions and then allowing these files to be strung together we can create a powerful yet flexible system By taking the standard out of one file and directing it to the standard in of another file we can build powerful and complex systems to accomplish our task So the file is the primary building block of the system All directories branch from the root of the file system represented by the single character The standard common subdirectories are as follows bin i
46. of undo so hitting u twice is the same as doing nothing at all it just undid your undo The Berkeley vi imple mentation nvi allows multiple level undo by typing dots it repeats your undo Most cabbage vi implementations though repeat your last command before your undo if you type dots Playing with files How do I save to a file W w lt filename gt The w command saves the current buffer analogous to save in a graphical editor If you specify lt filename gt the contents of the buffer is written to a different file If you specify a filename you normally won t be able to specify an already existing file If you must overwrite that file anyway then add a after the w w foo bar saves the buffer to foo bar whether or not foo bar already exists How do I edit a different file e lt filename gt e The e command either reloads the current file or the file specified if lt filename gt is given If your buffer has been modified and not yet saved you won t be able to reload the buffer unless you add a after the e e foo bar start editing foo bar discarding changes currently made to the buffer CONTENTS 173 How do I embed another file r lt filename gt Reads the contents of lt filename gt and embeds it into the cur rent buffer r lt command gt Executes lt command gt and embeds into the buffer the out put generated by the command r fortune s puts a short fortune into your b
47. only a short time and then control passes to another process This is why multi tasking operating systems like Linux are called time sharing systems X is a process which then in turn forks a new process when you call another program or open an xterm If you call a command in the xterm this again forks another process the command you asked to execute This forking means that a new program is begun with it s own process id PID while the calling program continues ready to execute more commands from the user The ps command is used to see what processes are running Output from the command typically looks something like this ps PID TTY STAT TIME COMMAND 639 p2 R 0 00 ps 16910 2 S 0 00 mingetty 17076 3 SW 0 00 mingetty 17077 4 SW 0 00 mingetty 17078 5 SW 0 00 mingetty 17079 6 SW 0 00 mingetty 26549 1 S 0 00 xterm sb 28490 1 S 0 00 xterm sb 28496 p2 S 0 00 su 28497 p2 S 0 00 bash The output of the ps command is interpreted as follows PID the process id number of the program TTY the terminal or pseudo terminal that the program is being run for STAT information about the status of the process R for runnable S for sleeping or suspend T for stopped or traced Z for a zombie process W if the process has no resident pages and N if the process has a positive nice value TIME COMMAND The name of the process CONTENTS 100 Background processes The getty process mingetty in the above example is a
48. option By default if neither u nor U is given backspaces which appear adjacent to an un derscore character are treated specially the underlined text is displayed using the terminal s hardware underlining capability Also backspaces which appear between two identical characters are treated specially the overstruck text is printed using the terminal s hardware boldface capa bility Other backspaces are deleted along with the preceding character Carriage returns immediately followed by a newline are deleted Other carriage returns are handled as specified by the r option Text which is overstruck or underlined can be searched for if neither u nor U is in effect V Displays the version number of less CONTENTS 32 version Same as V w Causes blank lines to be used to represent lines past the end of the file By default a tilde character is used xn Sets tab stops every n positions The default for n is 8 X Disables sending the termcap initialization and deinitialization strings to the terminal This is sometimes desirable if the deinitialization string does something unnecessary like clearing the screen yn Specifies a maximum number of lines to scroll for ward If it is necessary to scroll forward more than n lines the screen is repainted instead The c or C option may be used to repaint from the top of the screen if desired By default any forward movement causes scrolling z n Changes the default
49. output the last part of files SYNOPSIS tail e N bkm n N fqv bytes N bkm lines N follow quiet silent verbose help version file tail Nbcfklmqv file DESCRIPTION This documentation is no longer being maintained and may be inaccurate or incomplete The Texinfo documentation is now the authoritative source This manual page documents the GNU version of tail tail prints the last part 10 lines by default of each given file it reads from standard input if no files are given or when a filename of is encountered If more than one file is given it prints a header consisting of the file s name enclosed in gt and lt before the output for each file The GNU tail can output any amount of data unlike the Unix version which uses a fixed size buffer It has no r option print in reverse Reversing a file is really a different job from printing the end of a file the BSD tail can only reverse files that are at most as large as its buffer which is typically 32k A reliable and more versatile way to reverse files is the GNU tac command CONTENTS 82 OPTIONS tail accepts two option formats the new one in which numbers are arguments to the option letters and the old one in which a or and optional number precede any option letters If a number N starts with a tail begins printing with the Nth item from the start of ea
50. overwrite them from archive K starting file F begin at file F in the archive l one file system stay in local file system when creating an archive L tape length N change tapes after writing N 1024 bytes m modification time don t extract file modified time M multi volume create list extract multi volume archive N after date DATE newer DATE only store files newer than DATE o old archive portability write a V7 format archive rather than ANSI format O to stdout extract files to standard output p same permissions preserve permissions extract all protection in formation P absolute paths don t strip leading s from file names CONTENTS 85 preserve like p s R record number show record number within archive with each message remove files remove files after adding them to the archive s same order preserve order list of names to extract is sorted to match archive same owner create extracted files with the same ownership S sparse handle sparse files efficiently T files from F get names to extract or create from file F null T reads null terminated names disable C totals print total bytes written with create v verbose verbosely list files processed V label NAME create archive with volume name NAME version print tar program version number w interactive confirmation ask for confirmation for every action W verify attempt
51. preference The string given to the P option replaces the specified prompt string Certain characters in the string are interpreted specially The prompt mechanism is rather complicated to provide flexibility but the ordinary user need not under stand the details of constructing personalized prompt strings A percent sign followed by a single character is expanded according to what the following character is CONTENTS 38 bX Replaced by the byte offset into the current input file The b is followed by a single character shown as X above which specifies the line whose byte offset is to be used If the character is a t the byte offset of the top line in the display is used an m means use the middle line a b means use the bottom line a B means use the line just after the bottom line and a j means use the target line as specified by the j option B Replaced by the size of the current input file E Replaced by the name of the editor from the VISUAL environment variable or the EDITOR environment variable if VISUAL is not defined See the discussion of the LESSEDIT feature below f Replaced by the name of the current input file i Replaced by the index of the current file in the list of input files IX Replaced by the line number of a line in the input file The line to be used is determined by the X as with the b option L Replaced by the line number of the last line in the input file
52. ps uses to print out the abbreviated tty name in the TT field e g ps t1 O k1 k2 Order the process listing according to the multilevel sort specified by the sequence of short keys from SORT KEYS kl k2 Default order specifications exist for each of the various formats of ps These are over ridden by a user specified ordering The is quite optional merely re iterating the default direction on a key reverses direction only on the key it precedes As with t and pids the O option must be the last option in a single com mand argument but specifications in successive arguments are catenated pids List only the specified processes they are comma delimited The list must be given immediately after the last option in a single command line argument with no intervening space e g ps j1 4 5 Lists specified in subsequent arguments are catenated e g ps l 1 2 3 4 5 6 will list all of the processes 1 6 in long format If pids are given they are listed no matter what If a tty is given matching processes are listed no matter what These two features override the a and x flags LONG COMMAND LINE OPTIONS These options are preceded by a double hyphen sort X key key Choose a multi letter key from the SORT KEYS section X may be any convenient separator character To be GNU ish 6 use The is really optional since default direction is increasing numer
53. re enter insert mode you can t delete what you ve typed previously by hitting the backspace key One way to delete text a character at a time is to get into command mode and type either x or X the lower case version deletes the character at the cursor and behaves similarly to the delete key in graphical editors and the upper case one deletes the character just before the cursor and behaves similarly to the backspace key in graphical editors CONTENTS 170 d lt motion gt Typing the letter d followed by a motion command like h or 1 or more usefully w deletes text from the cursor to the target of the motion command For example dw deletes from the cursor to the start of the next word dd id Both of these commands delete the whole line To delete a whole bunch of text I just hold down the d key until I m satisfied Joining splitting J The j command joins the current line with the next A single space is added to the end of the first line unless the first line ended with a full stop in which case two spaces are added You split a line the conventional way go into insert mode and hit the return key Substituting text Yeah to replace text you can just remove and then insert but there are faster ways to do things s Replaces the character under the cursor More useful than it looks when you read two sections down S Replaces the whole line s lt from gt lt to gt Replaces the first instance of lt
54. root device to the drive where the OS images are stored by the command root 2 Load the kernel image by the command kernel 3 If you need modules load them with the command module or module nounzip 4 Run the command boot Linux can be booted in a similar manner You can load a kernel image by the command kernel and then run the command boot If the kernel requires some parameters just append the parameters to kernel after the file name of the kernel CONTENTS 111 It is relatively easy to boot Linux from GRUB because it somewhat resembles to boot a Multiboot compliant OS 1 Set GRUB s root device to the same drive as Linux s Probably the com mand find vmlinuz or similar can help you 2 Load the kernel grub gt kernel vmlinuz root dev hdal If you need to specify some kernel parameters just append them to the com mand For example to set vga to ext do this grub gt kernel vmlinuz root dev hdal vga ext Configuration You probably noticed that you need to type several commands to boot your OS There s a solution to that GRUB provides a menu interface from which you can select an item using arrow keys that will do everything to boot an OS To enable the menu you need a configuration file grub conf under the boot directory We ll analyze an example file The file first contains some general settings the menu interface relat
55. the fourth for other users not in the file s group with the same values chmod never changes the permissions of symbolic links the chmod system call cannot change their permissions This is not a problem since the permissions of symbolic links are never used However for each symbolic link listed on the command line chmod changes the permissions of the pointed to file In contrast chmod ignores symbolic links encountered during recursive directory traversals OPTIONS c changes Verbosely describe only files whose permissions actually change f silent quiet Do not print error messages about files whose permissions cannot be changed v verbose Verbosely describe changed permissions R recursive Recursively change permissions of directories and their contents help Print a usage message on standard output and exit successfully version Print version information on standard output then exit successfully EXAMPLES ls l rw r I 1 root root 0 Mar 26 19 22 firstfile CONTENTS 13 rw T 1 1 root root 0 Mar 26 19 22 fourfile rw T 1 1 root root 0 Mar 26 19 22 lastfile rw T 1 1 root root 0 Mar 26 19 22 onefile rw T 1 1 root root 0 Mar 26 19 22 thatfile rw T 1 1 root root 29 Mar 26 19 23 thisfile rw r r 1 root root 0 Mar 26 19 22 thosefiles rw T 1 1 root root 0 Mar 26 19 22 threefile rw T 1 1 root root 0 Mar 26 19 22 twofile chmod x firstfile rwxr xr x 1 root root 0 Mar 26 19 22 firstfile
56. the UNIX System Henry McGilton and Rachel Morgan McGraw Hill Book Company ISBN 0 07 045001 3 Running Linux Second Edition Matt Welsh and Lar Kaufman O Reilly amp As sociates Inc ISBN 1 56592 151 8 Learning the bash Shell Cameron Newham and Bill Rosenblatt O Reilly amp As sociates Inc ISBN 1 56592 147 X Learning the vi Editor Linda Lamb O Reilly amp Associates ISBN 0 937175 67 6 Linux in a Nutshell Second Edition Ellen Siever O Reilly amp Associates ISBN 1 56592 585 8 Open Sources Voices from the Open Source Revolution O Reilly amp Associates ISBN 1 56592 582 3 181
57. the name of the next file if there is one Finally any trailing spaces are truncated This is the default prompt For reference here are the defaults for the other two prompts m and M respectively Each is broken into two lines here for readability only CONTENTS 40 n f f m file i of m e END x Next x pB pB byte bB s s t 2 f n m file i of Ym ltline lt L L byte bB s s e END x Next x pB pB t And here is the default mes sage produced by the command RE m file i of m Itline Xlt L AL byte bB s s e END pB pB t The prompt expansion features are also used for another purpose if an environment variable LESSEDIT is defined it is used as the command to be executed when the v command is invoked The LESSEDIT string is expanded in the same way as the prompt strings The default value for LESSEDIT is E lm lm f Note that this expands to the editor name followed by a and the line number followed by the file name If your editor does not accept the linenumber syntax or has other differences in invocation syntax the LESSEDIT variable can be changed to modify this default SECURITY When the environment variable LESSSECURE is set to 1 less runs in a secure mode This means these features are disabled the shell command the pipe command e the examine command v the editing command s o log files k use of lesskey files t use of t
58. the root filesystem on the device suggested by etc fstab The only required argument is the kernel version to put onto the boot floppy You can create a boot floppy from the installed kernel or from a newly compiled kernel Some people prefer to use a boot floppy for testing a new kernel instead of loading it from the bootloader Here s a sample command line for creating a boot floppy on a newly installed Red Hat Linux system mkbootdisk device dev fd0 2 4 20 8 By default mkbootdisk give very little information except for errors For more information choose the verbose argment like this mkbootdisk device dev fd0 verbose 2 4 20 8 If you ran mkbootdisk without errors you can see what s on it by mounting the floppy mount t vfat dev fd0 mnt floppy Is l1 mnt floppy CONTENTS 103 total 1346 rwxr xr x 1 root root 208 Sep 23 19 16 boot msg rwxr xr x 1 root root 246298 Sep 22 01 24 initrd img r xr xr x 1 root root 7836 Sep 23 19 16 Idlinux sys rwxr xr x 1 root root 143 Sep 23 19 16 syslinux cfg rwxr xr x 1 root root 1122186 Mar 13 2003 vmlinuz So what are all these files cat mnt floppy boot msg Press lt return gt or wait 10 seconds to boot your Red Hat Linux system from dev rd cOd0p3 You may override the default linux kernel parameters by typing linux lt params gt followed by lt re turn gt if you like cat mnt floppy syslinux cfg default linux prompt 1 display boot msg
59. timeout 100 label linux kernel vmlinuz append initrd initrd img ro hdc ide scsi root dev rd c0d0p3 syslinux cfg is the configuration file for the bootloader to instruct it what then name of the ram disk is that hdc requires the ide scsi module and where the root file system is on the disk So boot msg is the message you get when you boot from the floppy initrd img is the ram disk that contains the temporary root file system with kernel modules and other information required to boot the system Idlinux sys is the system loader Now just to make sure you should boot from the floppy and make sure it works properly Once you ve tested it label it write protect it and put it in a safe place It s good insurance and like all good insurance we hope you ll never need it but you ll be glad you have it when you need it CONTENTS 104 LILO The majority of this information came directly from the documentation installed on the system during installation check usr share doc lilo xx x x doc User_Guide ps for a more detailed discussion of the finer points The Xs following lilo represent the specific version on your system If you are running X on your system you can view these documents with gv To read them on your system go Menu gt Graphic Programs and find ghostview Once you have it running File gt Open and drill down to usr share doc and find the file User_Guide ps You can also find informtion in the man pages for lilo 8
60. up I O according to the instructions in the commands It finds the commands in the files and runs them with options given on the command line Each step is made of one or more substeps each containing a particular instruc tion to the underlying operating system The shell itself is not Linux just the user interface to it Unix is one of the first operating systems to make the user inerface independant of the operating system The shell can do more than just pass commands to the system for execution The shell helps you use the computer The shell is a command interpreter that can expand and change the commands according to built in rules Of equal importance are wild card and command connection operators that make the command line more general and flexible The shell can take advantage of conditions in the environment managed by the shell to customise the way commands work CONTENTS 90 Bash s command line editing is one of the most powerful features It s very easy to correct mistakes and modify previous commands to save time and keystrokes Another major feature of bash is it s job control Job control allows you to stop start and pause any number of commands at the same time You may wish to modify the characteristics of your environment for this there are shell variables A shell variable is a name with an associated value Bash keeps track of several built in variables The convention is for shell variables to have names in all
61. usr src linux arch i386 boot bzImage time to move it into the boot directory root localhost mv arch i386 boot bzImage boot CONTENTS 159 Since we are already in the usr src linux directory we only need to use the rel ative path not the entire path to the image It s never recommended to replace a current version kernel before testing To do this run it first as linux new and make sure there are no errors So now it needs to be added to the etc lilo conf Edit the file to look similar to this boot dev hda map boot map install boot boot b prompt timeout 250 image boot bzImage label linux new root dev hdal read only image boot vmlinuz 2 4 20 label linux root dev hdal initrd boot initrd 2 4 20 img read only Then run lilo to include the new kernel If it is successful something similar to this should appear on the screen root localhost lilo Added linux new Added linux Now reboot the system and choose linux new to test the new kernel Other Administrative Tasks Making Backups Simple Backups Incremental Backups Scheduling Jobs Using Cron What is Cron Cron is a daemon that executes scheduled commands listed in a crontab file It checks every minute to see if there are ant jobs scheduled to run at that time if so it executes those jobs The cron deamon is usually started at bootup time What is crontab Crontab is the program used to install deinstall or list the tables u
62. Beginning Linux Neil Schneider James Jim G Sack Chris K Young Dave Kaupp Sang Woo Kang Copyright 2005 Contents This is being developed by members of the Kernel Panic Linux User Group and is designed to be a tutorial for beginning Linux users Not a compendium but enough to allow the beginning user to begin to operate their system and access the system resources So you have installed Linux and now you want to know how to use it That s what this book is about Learning something as complex as Linux is not easy without actually sitting at the system So why not just sit down right now at your system with your favorite beverage and try some of the things you will be reading Don t spill on the keyboard Basic Linux Commands and Usage Getting into the system Because Linux is a multi user multi tasking operating system similar to Unix you must log into the system The login system provides a certain degree of security by preventing unauthorized people from accessing your files It also provides access to the system Your login must be unique You can have multiple logins for different purposes If for example you were using you Linux system for accounting you might want a separate username for doing payroll so you might have a login called payroll Remember that Linux is case sensitive So JOE is not the same as joe Loging in verifies who is logging on to the system and sets up and environment for
63. ENTS Modem Configuration Kernel Daemon Configuration Search Help System 144 Package Management Red Hat Package Manager The Red Hat Package Manager allows users to package source code for new software into source and binary form so that binaries can be easily installed and tracked through the rpm database and source can be rebuilt easily The database of packages and files that can be used for verifying packages and querying for information about files and or packages RPM is very flexible and easy to use This is a brief overview of rpm For more information you can consult the man pages for rpm or you can visit the rpm web site at http www rpm org Installing and Upgrading Packages with RPM The basic method for installing a binary or source package with rpm is root localhost rpm i install options lt package_file gt If this is an upgrade of an already installed package you can choose the upgrade method to remove the old package while installing the new like this root localhost rpm U install options lt package_file gt You may also specify the lt package_file gt as an ftp style URL which will cause the package to be downloaded and then installed This will install the named package but will give no feedback to the person root installing the package To get more information you can use the the following options 145 CONTENTS 146 INSTALL AND UPGRADE OPTIONS force Same as using both repla
64. ESC F lt gt could be used to go forward to the gt which matches the lt in the top displayed line ESC B Followed by two characters acts like but uses the two characters as open and close brackets respectively For example ESC B lt gt could be used to go backward to the lt which matches the gt in the bottom displayed line m Followed by any lowercase letter marks the current position with that letter Single quote Followed by any lowercase letter returns to the position which was previously marked with that letter Followed by another single quote returns to the position at which the last large movement command was executed Followed by a or jumps to the beginning or end of the file respectively Marks are preserved when a new file is examined so the command can be used to switch between input files CONTENTS 25 X X Same as single quote pattern Search forward in the file for the N th line containing the pattern N defaults to 1 The pattern is a regular expression as recognized by ed The search starts at the second line displayed but see the a and j options which change this Certain characters are special if entered at the beginning of the pattern they modify the type of search rather than become part of the pattern N or Search for lines which do NOT match the pattern E or Search multiple files That is if the search reaches the beginning of the current
65. ET are e ascii The default character set BS TAB NL CR and formfeed are control characters all chars with values between 127 and 255 are binary and all others are normal latin1 Selects the ISO 8859 1 character set latin 1 is the same as ASCII except characters between 161 and 255 are treated as normal characters dos Selects a character set appropriate for MS DOS e koi8 r Selects a Russian character set next Selects a character set appropriate for NeXT computers In special cases it may be desired to tailor less to use a character set other than the ones definable by LESSCHARSET In this case the environment variable LESSCHARDEF can be used to define a character set It should be set to a string where each character in the string represents one character in the char acter set The character is used for a normal character c for control and b for binary CONTENTS 37 A decimal number may be used for repetition For example bccc4b would mean character 0 is binary 1 2 and 3 are control 4 5 6 and 7 are binary and 8 is normal All characters after the last are taken to be the same as the last so characters 9 through 255 would be normal This is an example and does not necessarily represent any real character set This table shows the value of LESSCHARDEF which is equivalent to each of the possible values for LESSCHARSET ascii 8bcecbcc18b95 b dos 8bcecbcc12bc5b95 b ebcdic 5bc6bcc7b
66. If man is not made suid then a cat directory should have mode 0777 if all users should be able to leave cat pages there The option c forces reformatting a page even if a recent cat page exists CONTENTS 52 ENVIRONMENT MANPATH If MANPATH is set its value is used as the path to search for manual pages MANROFFSEQ If MANROFFSEQ is set its value is used to determine the set of preprocessors run before running nroff or troff By default pages are passed through the table preprocessor before nroff MANSECT If MANSECT is set its value is used to determine which manual sections to search MANWIDTH If MANWIDTH is set its value is used as the width manpages should be displayed Otherwise the pages may be displayed over the whole width of your screen MANPAGER If MANPAGER is set its value is used as the name of the program to use to display the man page If not then PAGER is used If that has no value either usr bin less is is used LANG If LANG is set its value defines the name of the subdirectory where man first looks for man pages Thus the command LANG dk man 1 foo will cause man to look for the foo man page in dk man1 foo 1 and if it cannot find such a file then in manl foo 1 where is a directory on the search path NLSPATH LC_MESSAGES LANG The environment variables NLSPATH and LC_MESSAGES or LANG when the latter does not exist play a role in locating the message catalog But the English messages
67. LO primarily accesses the following parts of the system The root file system partition is important for two reasons first LILO sometimes has to tell the kernel where to look for it Second it is fre quently a convenient place for many other items LILO uses such as the boot sector the boot directory and the kernels CONTENTS 105 The boot sector contains the first part of LILO s boot loader It loads the much larger second stage loader Both loaders are typically stored in the file boot boot b The kernel is loaded and started by the boot loader Kernels typically reside in the root directory or in boot Booting Basics When booting from a floppy disk the first sector of the disk the so called boot sector is loaded That boot sector contains a small program that loads the respective operating system MS DOS boot sectors also contain a data area where disk and file system parameters cluster size number of sectors number of heads etc are stored When booting from a hard disk the very first sector of that disk the so called master boot record MBR is loaded This sector contains a loader program and the partition table of the disk The loader program usually loads the boot sector as if the system was booting from a floppy Note that there is no functional difference between the MBR and the boot sector other than that the MBR contains the partition information but doesn t contain any file system specific information
68. Pico use the z option To return back to the file you are editing after using ctrl z within Pico use the fg command The command fg is a basic unix command and may be covered in another section of this document Other options There are a few other options that can be used when starting Pico use man pico to view these other options e d Rub out CONTENTS 175 k cut text from here to end of the line r7 set column width for justifying Experiment and add to this document Help First things first Start pico hold down the CTRL key then the g key You will then be transported to the help screen The rest of these sections will assume that you read the help screen and assumes that you know what G means Use V you dont need the shift key for the upercase to view the next page s To exit the help screens use X Whats that stuff at the top of the screen Did you read the first page of the help screen It explains the status line at the top of the display G for help again Whats that stuff at the bottom of the display The help section G Says that the bottom 2 lines is the list the available editing commands The third line from the bottom which is blank most of the time is used for informational messages and for additional command input Lets look at each of these commands listed on the bottom two lines The Exit command getting out of Pico X quit pico Depending on one of
69. ROL and RIGHTARRO si multaneously Move the cursor one word to the right HOME ESC 0 Move the cursor to the beginning of the line END ESC Move the cursor to the end of the line BACKSPACE Delete the character to the left of the cursor or cancel the command if the command line is empty DELETE or ESC x Delete the character under the cursor BACKSPACE ESC BACKSPACE That is CONTROL and BACKSPACE si multaneously Delete the word to the left of the cursor DELETE ESC X or ESC DELETE That is CONTROL and DELETE simultaneously Delete the word under the cursor UPARROW ESC k Retrieve the previous command line DOWNARROW ESC j Retrieve the next command line TAB Complete the partial filename to the left of the cursor If it matches more than one filename the first match is entered into the command line Repeated TABs will cycle thru the other matching filenames If the completed filename is a directory a is appended to the filename On MS DOS systems a is appended The environment variable LESSSEPARATOR can be used to specify a different character to append to a directory name BACKTAB ESC TAB Like TAB but cycles in the reverse direction thru the matching filenames CONTENTS 34 L Complete the partial filename to the left of the cursor If it matches more than one filename all matches are entered into the command line if they fit U Unix or ESC MS DOS De
70. Use the command crontab l to view your crontab file At a quarter past the hour you should now have a new email with the subject My Crontab To remove your crontab use the crontab r command Note this will remove your entire crontab file If you would like to run a command at multiple times say every 30 minutes instead of just once per hour use a comma to separate the time sequences An example of once per 1 2 hour would look like this 15 45 echo on the quarter hour and 3 quarter hour mail yourusername To use crontab as a weekly reminder you could use the next example which sends me an email 15 minutes before Southpark starts on Saturday at 10 PM The email is sent at 9 45PM 45 21 6 echo SouthPark mail s TV SouthPark davek For the curious the personnel crontabs files are located in the var spool cron directory on Redhat These should not be edited manually in any case as the crontab deamon is notified of the changes when the crontab program edits the file CONTENTS 163 run parts explained Where is it Here s how to find the script on your system which run parts usr bin run parts And here s what it looks like before it s all discected in the piece by Jim Sack below This is a good example of a shell script Though the topic of shell scripts is beyond the purposes of this book it does help illuminate how crontab is set up on a Red Hat Linux system and give you a quic
71. X True if the line number of the specified line is known L True if the line number of the last line in the file is known m True if there is more than one input file n True if this is the first prompt in a new input file pX True if the percent into the current input file of the spec ified line is known s Same as B x True if there is a next input file that is if the current input file is not the last one Any characters other than the special ones question mark colon period per cent and backslash become literally part of the prompt Any of the special characters may be included in the prompt literally by preceding it with a back slash Some examples 7f f Standard input This prompt prints the filename if known otherwise the string Standard input fe ltLine lt pt pt btByte bt This prompt would print the filename if known The filename is followed by the line number if known otherwise the percent if known otherwise the byte offset if known Oth erwise a dash is printed Notice how each question mark has a matching period and how the after the pt is included literally by escaping it with a backslash n f f m file i of Ym e END x Next x t This prints the filename if this is the first prompt in a file followed by the file N of N message if there is more than one input file Then if we are at end of file the string END is printed followed by
72. a high performance journaling filesystem that provides rapid recovery from system crashes and the ability to support extremely large disk farms XFS is licensed under the GPL Maximum files system size 18K petabytes maximum file size 9K petabytes Mounting Filesystems Terms Mount Mounting a filesystem means making a filesystem accessible to the operating system Mounting point is where the filesystem is being mounted such as This has tree structure Syntax mount lt options gt source directory The most useful option is t which specifies the type of filesystem you are mounting Here are examples e mount t msdos dev hdal mnt dos e mount t vfat dev hda2 mnt windows e mount t iso9660 dev hdb mnt cd e mount t ext2 dev hdcl home e mount t nfs kernel panic com export kernel panic e mount t ext2 image img e mount t iso9660 cdimage linuxdist e mount t ntfs dev hdbl mnt nt CONTENTS 135 Creating Filesystems Make a filesystem Let s suppose for a minute that I just added a new hard disk into my system For our example we ll assume that it s and 10Gb slave drive on the first ide channel I want to create a place to store some of my important files I decide that this will be under my home directory so I create a directory that will become the mountpoint for a new filesystem called myfiles So the full path to this directory is home myusername myfiles Before I can use this new
73. a partition ifconfig Configure a network device manually pager Change the state of the internal pager partnew Make a primary partition parttype Change the type of a partition password Set a password for the menu interface rarp Initialize a network device via RARP serial Set up a serial device setkey Configure the key map splashimage Use a splash image terminal Choose a terminal terminfo Define escape sequences for a terminal tftpserver Specify a TF TP server unhide Unhide a partition Menu commands These commands can only be used in the menu default Set the default entry fallback Set the fallback entry hiddenmenu Hide the menu interface timeout Set the timeout title Start a menu entry CONTENTS 115 Summary Grub is a powerful bootloader with a built in shell like language It can be used to boot multiple Operating Systems as well as being a recovery tool for systems that have damaged bootloaders It s another tool every Linux user should become familiar with Specifying boot time options During the boot process it is possible to pass arguments to the kernel in order to enable specific modules or modify the default configuration set in the boot loader configuration It is important to note that spaces should not be used in a boot argument but only between separate arguments A list of values that are for a single argument are to be separated with a comma between the values and again w
74. ading the startup file cshre With Bourne like shells the f option disables filename pattern expansion which is not a generally desirable thing to do help Print a usage message on standard output and exit successfully l login Make the shell a login shell This means the following Unset all environment variables except TERM HOME and SHELL which are set as described above and USER and LOGNAME which are set even for the super user as described above and set PATH to a compiled in default value Change to USER s home directory Prepend to the shell s name to make it read its login startup file s CONTENTS 81 m p preserve environment Do not change the environment variables HOME USER LOGNAME or SHELL Run the shell given in the environment variable SHELL instead of USER s shell from etc passwd unless the user running su is not the superuser and USER s shell is re stricted A restricted shell is one that is not listed in the file etc shells or in a compiled in list if that file does not exist Parts of what this option does can be overridden by login and shell s shell shell Run SHELL instead of USER s shell from etc passwd unless the user running su is not the superuser and USER s shell is restricted version Print version information on standard output then exit successfully EXAMPLES tail NAME tail
75. ads 63 sectors 1653 cylinders Units cylinders of 16065 512 bytes Device Boot Start End Blocks Id System dev hdbl 1 413 2441406 83 Linux dev hdb2 414 827 2441406 83 Linux dev hdb3 828 1240 2441406 83 Linux dev hdb4 1241 1653 2441406 83 Linux I write out the drive partition with the w command in Linux which brings me back to the prompt mke2fs For this example I m going to create an ext3 filesystem The command I use is mke2fs which by default creates an ext2 filesystem Since ext3 is essentially an ext2 filesystem with journaling this is appropriate Remember I m going to create this partition to mount to home myusername myfiles So I use mke2fs like this mke2fs b 1024 j L myfiles dev hdb1 mke2fs 1 32 09 Nov 2002 Filesystem label home myusername myfiles OS type Linux Block size 1024 log 0 Fragment size 1024 log 0 307200 inodes 2449881 blocks CONTENTS 137 122494 blocks 5 00 reserved for the super user First data block 1 300 block groups 8192 blocks per group 8192 fragments per group 1024 inodes per group Superblock backups stored on blocks 8193 24577 40961 57345 73729 204801 221185 401409 663553 1024001 1990657 Writing inode tables done Creating journal 8192 blocks done Writing superblocks and filesystem accounting information done This filesystem will be automatically checked every 22 mounts or 180 days whichever comes first Use tune2fs c or i to override
76. ags files metacharacters in filenames such as filename completion TAB L Less can also be compiled to be permanently in secure mode CONTENTS 41 ENVIRONMENT VARIABLES Environment variables may be specified either in the system environment as usual or in a lesskey 1 file COLUMNS Sets the number of columns on the screen Takes precedence over the number of columns specified by the TERM variable EDITOR The name of the editor used for the v command HOME Name of the user s home directory used to find a lesskey file on Unix systems INIT Name of the user s init directory used to find a lesskey file on OS 2 systems LANG Language for determining the character set LC_CTYPE Language for determining the character set LESS Options which are passed to less automatically LESSBINFMT Format for displaying non printable non control characters LESSCHARDEF Defines a character set LESSCHARSET Selects a predefined character set LESSCLOSE Command line to invoke the optional input postprocessor LESSECHO Name of the lessecho program default lessecho The lessecho program is needed to expand metacharacters such as and in filenames on Unix systems LESSEDIT Editor prototype string used for the v command See discussion under PROMPTS LESSKEY Name of the default lesskey 1 file LESSMETACHARS List of characters which are considered metacharac ters by the shell LESSMETAESCAPE Pr
77. aining that semi colons may be replaced with newines if d 1 then echo Not a directory 1 exit 1 fi if the first argument 1 is not a directory name d give an error message and exit for iin 1 do d i amp amp continue if x i then i fi done CONTENTS 165 All the sanity checks are done now the real meat For every file call it i in the specified from arg 1 directory if it s a subdirectory do nothing just continue on with the next filename else if it s executable execute it It may be of interest to note that the for i in 1 gives fully qualified filenames exit 0 This is just good script programming practice Always ensure that some mean ingful return code is returned whatever the exit path Since this is the norma or successful return the convention of returning 0 is appropriate When this convention is observed you can calls this script from within other commands and be sure of being able to test for success or failure for this particular script success is defined as having no syntax errors in the command args The at command You can run a one time command with the at command The at command will run a command at a specified time in the future As an example suppose April 4 at 11 00 PM you start downoloading a large number of files through your 14 4 Kb modem Your wife needs the phone at 6AM So you run the following command
78. and extension nformal Like relaxed but many special characters lt spaces etc are rejected This is the default s trict Like normal but names may not contain long parts and special characters that are sometimes used on Linux but are not accepted by MS DOS are rejected spaces etc conv blinary conv t ext conv al uto The fat file system can perform CRLF lt gt NL MS DOS text format to UNIX text format conversion in the kernel The following conversion modes are available CONTENTS 63 binary no translation is performed This is the default text CRLF lt gt NL translation is performed on all files auto CRLF lt gt NL translation is performed on all files that don t have a well known binary extension The list of known extensions can be found at the beginning of fs fat misc c as of 2 0 the list is exe com bin app sys drv ovl ovr obj lib dll pif arc zip lha lzh zoo tar z arj tz taz tzp tpz gz tgz deb gif bmp tif gl jpg pcx tfm vf gf pk pxl dvi Programs that do computed seeks won t like in kernel text conversion Several people have had their data ruined by this translation Beware For file systems mounted in binary mode a conversion tool fromdos todos is available debug Turn on the debug flag A version string and a list of file system parameters will be printed these data are also printed if the param eters appear to be inconsi
79. and search path The directories and search order should check for SHELL Path to the shell command PS1 The primary prompt string The default value on Red Hat Linux is u h Here s a table of values you can use to customize you re prompt d The date in Weekday Month Day format CONTENTS 92 h The hostname n A carriage return and line feed s The name of the shell t The current time in HH MM SS format u The username of the current user w The current working directory W The basename of the current working directory The command number of the current command The history number of the current command If the effective UID is 0 print a otherwise print a nnn Character code in octal Print a backslash Begins a sequence of non prining characters such as terminal com mand sequences End of a sequence of non printing characters USER The current user of the shell MANPATH Path to the system man pages Typical setting would be something like this joe localhost echo MANPATH usr man usr X11R6 man usr lib perl5 man usr share perl5 man OTHERS CONTENTS 93 A Few Words About PATH One of the most baffling concepts for new users of Linux is the concept of PATH PATH is an environmental variable Environmental variables can come from many sources but most are set in the user s bash_profile Environmental vari ables like PATH tell the shell where to look for e
80. are eqn e grap g pic p tbl t vgrind v refer r This option overrides the MANROFFSEQ environment variable t Use usr bin groff Tps mandoc to format the man ual page passing the output to stdout The output from usr bin groff Tps mandoc may need to be passed through some filter or another before being printed w or path Don t actually display the man pages but do print the location s of the files that would be formatted or displayed If no argument is given display on stdout the list of directories that is searched by man for man pages If manpath is a link to man then manpath is equivalent to man path W Like w but print file names one per line without additional information This is useful in shell commands like man aW man xargs Is l CAT PAGES Man will try to save the formatted man pages in order to save formatting time the next time these pages are needed Traditionally formatted versions of pages in DIR manX are saved in DIR catX but other mappings from man dir to cat dir can be specified in etc man config No cat pages are saved when the required cat directory does not exist It is possible to make man suid to a user man Then if a cat directory has owner man and mode 0755 only writable by man and the cat files have owner man and mode 0644 or 0444 only writable by man or not writable at all no ordinary user can change the cat pages or put other files in the cat directory
81. ats devices subroutines and kernel internals on the system It is important for you to familiarize yourself with the use of man since it is the most readily available source of information on how to use Linux There is GUI interface under X called xman The man pages come in for a lot of criticism for being cryptic and taking for granted a lot of UNIX background Each page contains information about a single command or file The bottom of the page often contains references to other files and related commands Sometimes these references help clarify often not Man pages are divided into sections according to what they are used for User commands are in section 1 UNIX system calls are in section 2 subroutines 3 devices 4 and so on Sometimes an entry in two sections can have the same name and sometimes you will see a number following the name of a man page This CONTENTS 8 number is a reference to the man page section the command is found There are hard copy version available in bookstores These are usually subdivided into sections correpsonding to the the same sections as the commands For a complete description of the man command with all it s options see the man subsection of the Commands section below pwd NAME pwd print name of current working directory SYNOPSIS pwd help version DESCRIPTION This documentation is no longer being maintained and may be inaccurate or incomplete The Texinfo documentation is
82. ble the standard input is a tty and the f or force option is not given rm prompts the user for whether to remove the file If the response does not begin with y or Y the file is skipped GNU rm like every program that uses the getopt function to parse its argu ments lets you use the option to indicate that all following arguments are non options To remove a file called f in the current directory you could type either rm f or CONTENTS 76 rm f The Unix rm program s use of a single opment of the getopt standard syntax for this purpose predates the devel OPTIONS d directory Remove directories with unlink instead of rmdir and don t require a directory to be empty before trying to unlink it Only works for the super user Because unlinking a directory causes any files in the deleted directory to become unreferenced it is wise to fsck the filesystem after doing this f force Ignore nonexistent files and never prompt the user i interactive Prompt whether to remove each file If the response does not begin with y or Y the file is skipped r R recursive Remove the contents of directories recursively v verbose Print the name of each file before removing it help Print a usage message on standard output and exit successfully version Print version information on standard output then exit successfully EXAMPLES joe localhost
83. ble to take the standard output of one command and direct it to the standard input of another command This is known as piping we is a command the counts the number of words and characters If we want to know how many words are in our manfiles list we can read the input of the wc command from the output of the cat command like this cat manfiles list we 357 2111 14920 The symbol is known as the pipe symbol The standard output of the command on the left of the becomes the input of the command to the right We can string multiple commands together to perform complex actions on data using the pipe bash Environment Bash is an sh compatible command language interpreter that executes com mands read from the standard input or from a file Bash also incorporates useful features from the Korn and C shells ksh and csh Bash is the default shell for most Linux distributions Generally speaking a shell is a user interface to the Linux operating system It takes input from the user and interprets those command into instructions that the operating system can understand Bash is a character based interface It takes it s instructions from standard input in textual form and usually produces character based output The shell s job then is to interpret user input into commands understood by Linux It breaks up the lines of the command into pieces called words It then interprets these words according to rules The shell sets
84. calhost chown sam sam thisfile rw rw r 1 sam sam 29 Mar 26 19 23 thisfile Changing permissions The permissions or mode of a file or directory can be changed with the chmod command This can only be done by the owner of the file or super user root You cannot change a directory to a file or a file to directory with the chmod command There are several specifications that chmod accepts The symbolic mode which uses the letters ugoa rwxXstugo The letters ugoa control which users access will be changed The owner u other users in the group g others not in the group o or all users a The and operators determine whether the permissions are add or removed while the operator causes the permissions to be the only ones set for the file CONTENTS 97 root localhost ls l thatfile rw r 1 1 joe joe 0 Mar 30 21 46 thatfile root localhost chmod u x thatfile rwxr r 1 joe joe 0 Mar 30 21 46 thatfile The letters rwxXstugo select the new permissions for the affected users read r write w execute x or access for directories execute X only if the file is a directory or already has execute permissions for some users suid s set user or group ID on execution in other words execute the program as the owner of the file instead of the user that called the program save program text t sticky bit ignored by Linux on files on directories only owners of
85. capital letters Bash specific built ins are however defined in lowercase The envi ronmental variable will always be know by the subprocesses however the shell needs to be told about other variables options aliases etc that are to be communicated to subprocesses The way to do this is to declare them in the environment file On Linux systems this is commonly the bashrc file in the users home directory USERNAME System login name EDITOR Pathname to your text editor HISTFILE The name of the file where the bash history is kept Typically this is set to bash_history HISTSIZE The size of the history file How much history is saved MAIL Name of the file to check for incoming mail HOME Name of your home login directory HOSTNAME CONTENTS 91 The system hostname LANG The Language environment What language are you using LD_LIBRARY_PATH Where the shell is to look for shared libraries OLDPWD Previous directory before the last cd command PWD Current directory TERM Type of terminal you are using The variable TERM is vitaly important for using any screen editor and for third party applications The value of TERM must be a short character string with lowercase that appears as a filename in the terminfo database The terminfo databse describes how to tell terminals to do certain commaon things like position the cursor on the screen go into reverse video scroll insert text and so on PATH The comm
86. cc41b 9b7 9b5 b 8b6 10b6 b9 7b 9 8b8 17b3 3b9 7b9 8b8 6b10 b b b 1508859 8beccbcc18b95 33b koi8 r 8beccbcc18b95 b128 latinl 8beccbcc18b95 33b next 8bcccbcc18b95 bb125 bb If neither LESSCHARSET nor LESSCHARDEF is set but your system sup ports the setlocale interface less will use setlocale to determine the character set setlocale is controlled by setting the LANG or LC_CTYPE environment variables Control and binary characters are displayed in standout reverse video Each such character is displayed in caret notation if pos sible e g A for control A Caret notation is used only if inverting the 0100 bit results in a normal printable character Otherwise the character is displayed as a hex number in angle brackets This format can be changed by setting the LESSBINFMT environment variable LESSBINFMT may begin with a and one character to select the display at tribute k is blinking d is bold u is underlined s is standout and n is normal If LESSBINFMT does not begin with a normal attribute is assumed The remainder of LESSBINFMT is a string which may include one printfstyle escape sequence a followed by x X o d etc For example if LESSBINFMT is u x binary characters are displayed in underlined hex adecimal surrounded by brackets The default if no LESSBINFMT is specified is d lt X gt PROMPTS The P option allows you to tailor the prompt to your
87. ccess remote filesys tems A great amount of research and details are involved in this since a network is inherently unreliable Transfering files take time there are security encryption authentication problems and other challenges Linux supports nfs but it is still incomplete compared to some other operating systems This is something most single user system administrators don t have to worry about proc the proc directory contains files that are not part of any filesystem as sociated with your hard disks CD ROM or any other physical storage device connected to your system except arguably your RAM Rather these files are part of a virtual filesystem enabled or disabled in the Linux kernel when it is compiled CONTENTS 134 Reiserfs is a filesystem using a plug in based object oriented variant on classi cal balanced tree algorithms ReiserFS has fast journaling which means that you don t spend your life waiting for fsck ReiserFS does meta data journaling enabling fast crash recovery without the expense of full data journaling maximum file system size 16 Terabytes Maximum files size 2 10 petabytes Smbfs is a filesystem which understands the SMB protocol This is the protocol Windows for Workgroups Windows NT or LAN Manager use to talk to each other It was inspired by samba the program by Andrew Tridgell that turns any unix site into a file server for DOS or Windows clients XFS SGI s XFS filesystem for Linux is
88. cepkgs replacefiles and oldpackage h hash Print 50 hash marks as the package archive is unpacked Use with v for a nice display oldpackage Allow an upgrade to replace a newer package with an older one percent Print percentages as files are unpacked from the package archive This is intended to make RPM easy to run from other tools replacefiles Install the packages even if they replace files from other already installed packages replacepkgs Install the packages even if some of them are already installed on this system allfiles Installs or upgrades all the missingok files in the package regardless if they exist nodeps Don t do a dependency check before installing to upgrading a package noscripts Don t execute the preinstall or postinstall scripts notriggers Don t execute scripts which are triggered by the installation of this package excludedocs Don t install any files which are marked as docu mentation which includes man pages and texinfo documents includedocs Install documentation files This is only needed if excludedocs 1 is specified in an rpmrc file test Do not install the package simply check for and report potential conflicts prefix lt path gt This sets the installation prefix to lt path gt for relocatable packages ignorearch This allows installation or upgrading even if the architectures of the binary RPM and host don t match ignoreos Th
89. ch file instead of from the end c N bytes N Tail by N bytes N is a nonzero integer optionally followed by one of the following characters to specify a different unit b 512 byte blocks k 1 kilobyte blocks m 1 megabyte blocks f follow Loop forever trying to read more characters at the end of the file on the assumption that the file is growing Ignored if reading from a pipe If more than one file is given tail prints a header when ever it gets output from a different file to indicate which file that output is from l n N lines N Tail by N lines l is only recognized using the old option format q quiet silent Never print filename headers v verbose Always print filename headers help Print a usage message and exit with a status code indicating success version Print version information on standard output then exit EXAMPLES Let s watch syslog tail f var log messages Checking on mail deliveries tail f var log maillog tar NAME tar The GNU version of the tar archiving utility CONTENTS 83 SYNOPSIS tar A catenate concatenate c create d diff compare r append t list u update x extract get atime preserve b block size N B read full blocks C directory DIR checkpoint f file HOST NAMEIF force local F info script F new volume script F G incremental g listed incremental F h dereference i
90. ch highlighting is enabled and a search pattern begins with a more text than the matching string may be highlighted On some systems setlocale claims that ASCII characters 0 thru 31 are con trol characters rather than binary characters This causes less to treat some binary files as ordinary non binary files To workaround this problem set the environment variable LESSCHARSET to ascii or whatever character set is appropriate COPYRIGHT Copyright c 1984 1985 1989 1994 1995 1996 Mark Nudelman Comments to markn fog net CONTENTS 43 locate NAME locate list files in databases that match a pattern SYNOPSIS locate d path database path version help pattern DESCRIPTION This manual page documents the GNU version of locate For each given pattern locate searches one or more databases of file names and displays the file names that contain the pattern Patterns can contain shell style metacharacters and The metacharacters do not treat or specially Therefore a pattern foo bar can match a file name that contains foo3 bar and a pattern duck can match a file name that contains lake ducky Patterns that con tain metacharacters should be quoted to protect them from expansion by the shell If a pattern is a plain string it contains no metacharacters locate displays all file names in the database that contain that string anywhere
91. cutive pound signs are replaced with a single pound sign The filename is inserted into the command line list of files so that it can be seen by subsequent n and p commands If the filename consists of several files they are all inserted into the list of files and the first one is examined If the filename contains one or more spaces the entire filename should be enclosed in double quotes also see the option X V or E Same as e Warning some systems use V as a special literaliza tion character On such systems you may not be able to use V n Examine the next file from the list of files given in the command line If a number N is specified the N th next file is examined p Examine the previous file in the command line list If a number N is specified the N th previous file is examined x Examine the first file in the command line list If a number N is specified the N th file in the list is examined or G or f Prints some information about the file being viewed including its name and the line number and byte offset of the bottom line being displayed If possible it also prints the length of the file the number of lines in the file and the percent of the file above the last displayed line Followed by one of the command line option letters see below this will change the setting of that option and print a message describing the new setting If the option letter has a numeric value such as b or h or a
92. d nobody if you happen to monitor your logs This is one if the programs in the cron daily directory doing its job The cron weekly is set to run Thursday at 4 22 AM and the cron monthly is set to run at on the first day of the month at 4 22 AM Modifying the system crontab If there are any programs you would like run at these scheduled times from the administrator account its easy to just copy the program or batch file to that directory you can even make a link to the program if you like Otherwise see the next section about creating a crontab file for a regular users account To have your time updated every night edit a file called etc cron daily z sync time with the following CONTENTS 162 usr bin rdate s time ucla edu Then use the chmod command to make it executable chmod x etc cron daily z sync time I prefixed the filename with a z because the files are executed alphabetically so this program will be executed last Creating your personnel crontab file To create or edit your own personnel crontab file use the command crontab e you should be in an editor defined by your EDITOR environment variable if not set you may be in the vi editor by default If this is your first crontab file you should have a blank file Lets add something to execute every hour on the quarter hour Add this line 15 echo Test of my crontab mail s My Crontab you rusername Now save the file and quit your editor
93. d with the same syntax as swapon swapoff dev hdb2 ISO mkisofs CONTENTS 140 Checking and Repairing Filesystems fsck Red Hat Control Panel The Red Hat control panel is a gui interface running under X that allows easy administration of a Red Hat Linux System Most of the configuration parameters can be adjusted using the control panel control panel has to be run by the super user root If you are running as a regular user as recommended you can use the su command in a xterm to become root then start control panel from that xterm If you just call control panel you may get an error like this su Password control panel WARNING cannot open display To activate the control panel from an xterm where you su to root take the following stepst su Password export DISPLAY 0 0 control panel Runlevel Editor The Runlevel Editor can be called from the control panel or it can be called by it s program name tksyv su Password export DISPLAY 0 0 tksysv A word of warning from the Help screen of tksysv Be warned it does not cache changes When you change something it s changed It does store a backup of your etc rc d tree in tmp tksysv rc d CONTENTS 141 so you can restore it with cp arf tmp tksysv re d etc It makes this copy every time you run it so don t messup restart and then try and recover There is also more information about how to us
94. ding the read permissions are also set for that directory The x permission for a directory is sometimes called the search permission By combining the three different levels of permissions and three user levels there are nine different combinations of permisssions possible rwxrwxrwx 2 joe joe 29 19 22 file or directory name LETT TL TET LTT I I Date of creation LPT TT ITLL TLL 1 Size bytes III I LTT TTL I group III III I owner user CONTENTS 96 number of links eee execute for public other Heats write for public other read for public other 557 execute for group ee write for group BE SE A read for group execute for owner user NT ENES write for owner user me A E read for owner user Be ee suid amp sticky bit amp directory The left three letters refer to the owner of the file the middle three to the group and the right three refer to the users public Missing permissions are refered to as protection and are indicated by a dash The nine protections are collectively the mode of the file or directory and can be changed wiht the chmod command Changing ownership The ownership of files can be changed by root This is done using the chown command root localhost Is 1 thisfile rw rw r 1 joe joe 29 Mar 26 19 23 thisfile root lo
95. directory from which this summary was extracted hdx is recognized for all x from a to h such as hdc idex is recognized for all x from 0 to 3 such as idel CONTENTS 121 hdx noprobe drive may be present but do not probe for it hdx none drive is NOT present ignore cmos and do not probe hdx nowerr ignore the WRERR_STAT bit on this drive hdx cdrom drive is present and is a cdrom drive hdx cyl head sect disk drive is present with specified geometry hdx autotune driver will attempt to tune interface speed to the fastest PIO mode supported if possible for this drive only Not fully supported by all chipset types and quite likely to cause trouble with older odd IDE drives idex noprobe do not attempt to access use this interface idex base probe for an interface at the addr specified where base is usually 0x1f0 or 0x170 and ctl is assumed to be base 0x206 idex base ctl specify both base and ctl idex base ctl irq specify base ctl and irq number idex autotune driver will attempt to tune interface speed to the fastest PIO mode supported for all drives on this interface Not fully supported by all chipset types and quite likely to cause trouble with older odd IDE drives idex noautotune driver will NOT attempt to tune interface speed This is the default for most chipsets except the cmd640 idex serialize do not overlap operations on idex and ide x 1 The follow
96. e notion of ranges which come just after the colon Ranges are best described by examples The 1 and commands mentioned earlier are not really commands but line specifications which stand for the first line and the last line respectively In addition the dot stands for the current line You can offset this by a certain number of lines by using or followed by a number For example 3 refers to three lines up from the end and 5 refers to the fifth line down from the current one A range is specified by two line specifications separated by a comma For ex ample 2 5 means between lines 2 and 5 including lines 2 and 5 The percent symbol is a shortcut for 1 And now some real life examples d zaps the whole buffer 1 4d deletes everything from the next line down to the end of the buffer except the last four lines If your email signature is say four lines long this is a convenient way to zap your message without zapping your signature with it s foo bar g replaces all instances of foo with bar 3j joins the current line with the three following lines CONTENTS 172 How do I repeat what I just did The dot command repeats the last command you did that actually changed the buffer Movement commands do not count Oops I ve made some fatally awful or awfully fatal mistake u The standard way to undo the last action Note that many implementations of vi only have a single level
97. e suffix used for making simple backup files can be set with the SIMPLE_BACKUP_SUFFIX environment variable which can be overridden by this option If neither of those is given the default is as it is in Emacs V version control numbered existing simple The type of backups made can be set with the VERSION_CONTROL environment variable which can be overridden by this option If VERSION_CONTROL is not set and this option is not given the default backup type is existing The value of the VERSION_CONTROL environment variable and the argument to this option are like the GNU Emacs version control variable they also rec ognize synonyms that are more descriptive The valid values are unique abbreviations are accepted e t or numbered Always make numbered backups e nil or existing Make numbered backups of files that already have them simple backups of the others e never or simple Always make simple backups CONTENTS 17 EXAMPLES cat thisfile This is the text in thisfile cat thatfile cp thisfile thatfile cp overwrite thatfile y cat thatfile This is the text in thisfile df NAME df summarize free disk space SYNOPSIS df aikPv t fstype x fstype all nodes type fstype exclude type fstype kilobytes portabil ity print type help version filename DESCRIPTION This documentation is no longer being mainta
98. e the name of your target partition even with minimal knowledge of the syntax Note that GRUB does _not_ distinguish IDE from SCSI it simply counts the drive numbers from zero regardless of their type Normally any IDE drive number is less than any SCSI drive number although that is not true if you change the boot sequence by swapping IDE and SCSI drives in your BIOS Now the question is how to specify a file Again see this example hd0 0 vmlinuz This specifies the file named vmlinuz found on the first partition of the first hard disk drive How to boot operating systems GRUB has two distinct boot methods One of the two is to load an operat ing system directly and the other is to chain load another boot loader which then will load an operating system actually Generally speaking the former is desirable because you don t need to install or maintain other boot loaders and GRUB is flexible enough to load an operating system from an arbitrary disk partition However the latter is sometimes required since GRUB doesn t support all the existing operating systems natively Loading an operating system directly Multiboot is the native format supported by GRUB For the sake of convenience there are also support for Linux FreeBSD NetBSD and OpenBSD If you want to boot other operating systems you will have to chain load them Generally GRUB can boot any Multiboot compliant OS in the following steps 1 Set GRUB s
99. e the Runlevel Editor in the help screen once you have the application running When you start the Runlevel Editor you will be greeted by a panel consisting of nine selection boxes and four command buttons The left selection box contains all the available system daemons or programs This is where you choose the applications you wish to have started On the right are eight selection panels representing runlevels two through five one for starting programs and snother for stopping The runlevels are as follows Runlevel 2 Multi user with no network active Runlevel 3 Multi user with networking active Runlevel 4 Custom runlevel Runlevel 5 Multi user with networking and X X login and X gui started with system initialization Runlevel 1 single user mode is not configurable from the Runlevel Editor and Runlevel 6 is shutdown To add an application to a runlevel pick the application in the left panel then click on add A new dialog box will appear You must choose whether you are editing the start or stopping of the daemon and at what runlevel your choices will effect To remove an application from a runlevel simply click on the application name at the runlevel you wish to effect and then choose the Remove button to prevent it from starting or stopping at that runlevel 3 3 2 Time and Date The control panel contains a gui application Red Hat calls timetool for setting the system time and changing from twelve to twenty four
100. e will be changed the user who owns it u other users in the file s group g other users not in the file s group o or all users a If none of these are given the effect is as if a were given but bits that are set in the umask are not affected The operator causes the permissions selected to be added to the existing permissions of each file causes them to be removed and causes them to be the only permissions that the file has The letters rwxXstugo select the new permissions for the affected users read r write w execute or access for directories x execute only if the file is a directory or already has execute permission for some user X set user or group ID on execution s save program text on swap device t the permissions that the user who owns the file currently has for it u the permissions that other users in the file s group have for it g and the permissions that other users not in the file s group have for it o A numeric mode is from one to four octal digits 0 7 derived by adding up the bits with values 4 2 and 1 Any omitted digits are assumed to be leading zeros The first digit selects the set user ID 4 and set group ID 2 and save text image 1 attributes The second digit selects permissions for the user who owns the file read 4 write 2 and execute 1 the third selects permissions for other users in the file s group with the same values and
101. e word single which instructs init to boot the computer in single user mode and not launch all the usual daemons The root Argument This argument tells the kernel what device is to be used as the root filesystem while booting The default of this setting is the value of the root device of the system that the kernel was built on or the parameters set during the installation in lilo conf or grub conf For example if the lilo conf has root dev hdal in the stanza for that image then the default root device would be dev hdal To override this default value and select the first partition on the second hard drive as the root device one would use root dev hdbl Valid root devices are any of the following devices 1 dev hdaN to dev hddN which is partition N on ST 506 compatible disk a to d 2 dev sdaN to dev sdeN which is partition N on SCSI compatible disk a toe 3 dev xdaN to dev xdbN which is partition N on XT compatible disk a to b CONTENTS 117 4 dev fdN which is floppy disk drive number N Having N 0 would be the DOS A drive and N 1 would be B 5 dev nfs which is not really a device but rather a flag to tell the kernel to get the root fs via the network 6 dev ram which is the RAM disk The more awkward and less portable numeric specification of possible disk de vices in major minor format is also accepted So for example dev sdal is major 8 mino
102. ed you might tell csh setenv LESS options or if you use sh LESS options export LESS The environment variable is parsed before the command line so command line options override the LESS environment variable If an option appears in the LESS variable it can be reset to its default on the command line by beginning the command line option with For options like P which take a following string a dollar sign may be used to signal the end of the string This option displays a summary of the commands accepted by less the same as the h command Depending on how your shell interprets the question mark it may be necessary to quote the question mark thus help Same as a Causes searches to start after the last line displayed on the screen thus skipping all lines displayed on the screen By default searches start at the second line on the screen or after the last found line see the j option bn Specifies the number of buffers less will use for each file Buffers are 1K and by default 10 buffers are used for each file except if the file is a pipe see the B option The number n specifies a different number of buffers to use B By default when data is read from a pipe buffers are allocated automati cally as needed If a large amount of data is read from the pipe this can cause a large amount of memory to be allocated The B option disables this automatic allocation of buffers fo
103. ed options You can put these commands before any of the items starting with title Sample boot menu configuration file As you may have guessed these lines are comments Lines starting with a hash character and blank lines are ignored by GRUB By default boot the first entry default 0 The first entry here counting starts with number zero not one will be the default choice Boot automatically after 30 secs timeout 30 As the comment says GRUB will boot automatically in 30 seconds unless interrupted with a keypress Fallback to the second entry fallback 1 If for any reason the default entry doesn t work fall back to the second one this is rarely used for obvious reasons CONTENTS 112 Now on to the actual OS definitions You will see that each entry begins with a special command title and the action is described after it Note that there is no command boot at the end of each item That is because GRUB automatically executes boot if it loads other commands successfully The argument for the command title is used to display a short title description of the entry in the menu Since title displays the argument as is you can write basically anything in there For booting Linux title Linux kernel hd0 0 vmlinuz root dev hdal This boots Linux from the first hard disk For booting Windows NT or Windows95 title Windows NT Windows 95 boot me
104. efix which less will add before each metacharacter in a command sent to the shell If LESSMETAESCAPE is an empty string commands containing metacharacters will not be passed to the shell LESSOPEN Command line to invoke the optional input preprocessor LESSSECURE Runs less in secure mode See discussion under SECURITY LESSSEPARATORString to be appended to a directory name in filename com pletion CONTENTS 42 LINES Sets the number of lines on the screen Takes precedence over the number of lines specified by the TERM variable PATH User s search path used to find a lesskey file on MS DOS and OS 2 systems SHELL The shell used to execute the command as well as to expand file names TERM The type of terminal on which less is being run VISUAL The name of the editor used for the v command SEE ALSO lesskey 1 WARNINGS The command and prompts unless changed by P report the line number of the line at the top of the screen but the byte and per cent of the line at the bottom of the screen If the e command is used to name more than one file and one of the named files has been viewed previously the new files may be entered into the list in an unexpected order On certain older terminals the so called magic cookie terminals search high lighting will cause an erroneous display On such terminals search highlighting is disabled by default to avoid possible problems In certain cases when sear
105. el developers can profile how and where the kernel is spending its CPU cycles in an effort to maximize efficiency and performance quiet only important and system critical kernel messages are printed to the con sole Normal messages about hardware detection at boot are suppressed raid accepts noautodetect at the moment See also md reboot controls the type of reboot that Linux will do when it resets the computer reserve used to protect I O port regions from probes resume If you are using software suspend then this will allow you to specify the file name of the suspend to disk data that you want the machine to resume from scsi logging turns on logging of all SCSI events error scan mlqueue ml complete Ilqueue Ilcomplete hlqueue hlcomplete st boot time configuration of the SCSI tape driver video argument not avail in v2 0 kernels is used when the frame buffer device abstraction layer is built into the kernel vga not really a boot argument allows the setup code to use the video BIOS to change the default display mode before actually booting the Linux kernel IDE Disk CD ROM Driver Parameters The IDE driver accepts a number of parameters which range from disk ge ometry specifications to support for advanced or broken controller chips The following is a summary of some of the more common boot arguments For full details you really should consult the file ide txt in the kernel source tree linux Documentation
106. erver Settings gt Services The de fault it to edit the currently running Runlevel By choosing the Edit Runlevel tab you can edit runlevel 3 4 and 5 You can run man redhat config services for a synopsis on this program There is an ncurses based tool for configuring runlevels It too will default to the current runlevel However according to the man page you can edit different runlevels by calling it with the level argument Calling man ntsysv will give you more information for running the runlevel editor There is also a general purpose command line tool for managing runlevels sbin chkconfig for querying and updating the runlevel system Reading about chkconfig reveals some of the details about the mysterious numbers S40 etc in the scripts Checkout also the chkconfig data that is embedded in the com ments at the beginning of etc rc d init d scripts the ones that are managed by chkconfig sbin init or sbin telinit for changing runlevel re reading the inittab file or activating ondemand processes See man init for details Packages and related docs SysVinit provides the basic executable components of the SysV init scheme man pages provided are last lastb mesg wall initscript inittab halt killall pidof poweroff reboot runlevel shutdown sulogin telinit Initscripts provides the basic scripts utility programs and the default runlevel links man pages are doexec ipcalc netreport user
107. esgid n and resuid n The ext2 file system reserves a certain percentage of the available space by default 5 see mke2fs 8 and tune2fs 8 These options determine who can use the reserved blocks Roughly whoever has the specified uid or belongs to the specified group sb n Instead of block 1 use block n as superblock This could be useful when the filesystem has been dam aged Usually copies of the superblock are found every 8192 blocks in block 1 8193 16385 Thus one gets hundreds or even thousands of copies of the superblock on a big filesystem I do not know of options to mke2fs that would cause fewer copies to be written grpquota noquota quota usrquota These options are accepted but ignored Mount options for fat Note fat is not a separate filesystem but a common part of the msdos umsdos and vfat filesystems blocksize 512 blocksize 1024 Set blocksize default 512 uid value and gid value Set the owner and group of all files Default the uid and gid of the current process umask value Set the umask the bitmask of the permissions that are not present The default is the umask of the current process The value is given in octal check value Three different levels of pickyness can be chosen r elaxed Upper and lower case are accepted and equivalent long name parts are truncated e g verylongname foobar becomes verylong foo lead ing and embedded spaces are accepted in each name part name
108. essing the file with the N option This is useful when the compressed file name was truncated or when the time stamp was not preserved after a file transfer Compressed files can be restored to their original form using gzip d or gunzip or zcat If the original name saved in the compressed file is not suitable for its file system a new name is constructed from the original one to make it legal gunzip takes a list of files on its command line and replaces each file whose name ends with gz gz z z z or Z and which begins with the correct magic number with an uncompressed file without the original extension gunzip also recognizes the special extensions tgz and taz as shorthands for tar gz and tar Z respectively When compressing gzip uses the tgz extension if neces sary instead of truncating a file with a tar extension 152 CONTENTS 153 OPTIONS a ascii Ascii text mode convert end of lines using local conventions This option is supported only on some non Unix systems For MSDOS CR LF is converted to LF when compressing and LF is converted to CR LF when decompressing c stdout to stdout Write output on standard output keep original files un changed If there are several input files the output consists of a sequence of independently compressed members To obtain better compression concatenate all input files before compressing them d decompress uncompress Decompress f force Force compression or
109. et FileSystem that enables using UNIX file servers on a Windows network or visa versa A good filesystem provides or supports e good performance defragmentation minimized loss of data during crash journaling e easy recovery of data from damaged filesystem flexibility 2 byte code filename long filename special files e easy management self diagnostics tools large capacity Gigabytes Terabytes e large file security user id group id access control permission capability of being distributed network filesystem e low to zero fragmentation fragmentation This happens a lot with Windows DOS FAT filesystem it refers to the phenomenon when a file is physicall divided and scattered around the disk while logically seen as a one single file Programs such as defrag exe or Norton s Speeddisk regroups the files to provide optimal performance to the operating system Linux has one but it s obsolete since Ext2fs does this internally CONTENTS 132 Journaling File Systems If there is a system crash before buffers have been written to disk it will cause the system to behave in an inconsistent way after reboot A file deleted in the cache may still remain on the hard disk The fsck recover tool for ext2fs has to scan the entire disk partition in order to get the file system into a consistent state after a crash On a very large file system of serveral hundred gigabytes getting the system back to a consistent
110. etc Rock Ridge is an extension to iso9660 that provides all of these unix like fea tures Basically there are extensions to each directory record that supply all of the additional information and when Rock Ridge is in use the filesystem is indistinguishable from a normal UNIX file system except that it is read only of course norock Disable the use of Rock Ridge extensions even if available Cf map check r elaxed check s trict With check relaxed a filename is first converted to lower case before doing the lookup This is probably only meaningful together with norock and map normal Default check strict uid value and gid value Give all files in the file system the indicated user or group id possibly overriding the information found in the Rock Ridge extensions Default uid 0 gid 0 map n ormal map olff For non Rock Ridge volumes normal name trans lation maps upper to lower case ASCII drops a trailing 1 and converts to With map off no name translation is done See norock Default map normal mode value For non Rock Ridge volumes give all files the indicated mode Default read permission for everybody Since Linux 2 1 37 one no longer needs to specify the mode in decimal Octal is indicated by a leading 0 unhide Also show hidden and associated files block 512 1024 2048 Set the block size to the indicated value Default block 1024 conv aluto conv b inary conv mltext co
111. f e A bug or security vulnerability has been discovered in the kernel version you are currently running and you want to fix it Obtaining Kernel Sources There are several ways to obtain kernel sources You can install the sources that come with your distribution If you are running Red Hat you can use the Red Hat Package Manager to install the sources from a rpm file You can download the tar ball from the kernel ftp site or one of it s mirrors The choice is yours Loadable Kernel Modules Kernel modules are pieces of the kernel code which are not included directly in the kernel They are compiled seperately and they can be inserted and removed 156 CONTENTS 157 from the running kernel at almost any time So they extend the capabilities of the kernel while keeping the core components small and compact Many popular devices like the PCMCIA drivers and the ftape drivers are built as loadable modules Rarely used options are often compiled as loadable modules conserving memory while still allowing those options to be run Loadable mod ules also allow a generic kernel to be built that can run across a wide array of hardware configurations Red Hat makes extensive use of loadable modules in their distributions Configuring for the compile Once you chosen your kernel source next step is to configure for your compile This is just a simple outline of the steps It will not include a discussion of the various options to c
112. file without finding a match the search continues in the previous file in the command line list F or Begin the search at the first line of the FIRST file in the command line list regardless of what is currently displayed on the screen or the settings of the a or j options K Highlight any text which matches the pattern on the current screen but don t move to the first match KEEP current position R Don t interpret regular expression metacharacters that is do a simple tex tual comparison pattern Search backward in the file for the N th line containing the pattern The search starts at the line immediately before the top line displayed Certain characters are special as in the command N or Search for lines which do NOT match the pattern E or Search multiple files That is if the search reaches the beginning of the current file without finding a match the search continues in the previous file in the command line list F or Begin the search at the last line of the last file in the command line list regard less of what is currently displayed on the screen or the settings of the a or j options K As in forward searches R As in forward searches ESC pattern Same as ESC pattern Same as n Repeat previous search for N th line contain ing the last pattern If the previous search was modified by N the search is made for the N th line NOT containing the pattern If the previ
113. fixed with no to specify the file system types on which no action should be taken This can be meaningful with the a option For example the command mount a t nomsdos ext mounts all file systems except those of type msdos and ext o Options are specified with a o flag followed by a comma separated string of options Some of these options are only useful when they appear in the etc fstab file The following options apply to any file system that is being mounted e async All I O to the file system should be done asynchronously e atime Update inode access time for each access This is the default CONTENTS 59 auto Can be mounted with the a option defaults Use default options rw suid dev exec auto nouser and async dev Interpret character or block special devices on the file system exec Permit execution of binaries noatime Do not update inode access times on this file system e g for faster access on the news spool to speed up news servers noauto Can only be mounted explicitly i e the a option will not cause the file system to be mounted nodev Do not interpret character or block special devices on the file system noexec Do not allow execution of any binaries on the mounted filesystem This option might be useful for a server that has file systems containing binaries for architectures other than its own nosuid Do not allow set user identifier or set group identifier bits to take effect nouser Fo
114. flaw in HP UX it also affects the HP UX ls program If there was a single standard for the English language it would not be necessary to support redundant spellings EXAMPLES man NAME man format and display the on line manual pages manpath determine user s search path for man pages CONTENTS 50 SYNOPSIS man acdfhkKtwW m system p string C config_file M path P pager S section_list section name DESCRIPTION man formats and displays the on line manual pages This version knows about the MANPATH and MAN PAGER environment variables so you can have your own set s of personal man pages and choose whatever program you like to display the formatted pages If section is specified man only looks in that section of the manual You may also specify the order to search the sections for entries and which preprocessors to run on the source files via command line options or environment variables If name contains a then it is first tried as a filename so that you can do man foo 5 or even man cd foo bar 1 gz OPTIONS C config_file Specify the man conf file to use the default is etc man config See man conf 5 M path Specify the list of directories to search for man pages If no such op tion is given the environment variable MANPATH is used If no such environment variable is found the default list is found by consulting etc man config An empty substring of MANPATH denotes the default list
115. g regular destination files 1 link Make hard links instead of copies of non directories P parents Form the name of each destination file by appending to the tar get directory a slash and the specified name of the source file The last argument given to cp must be the name of an existing directory For ex ample the command cp parents a b c existing_dir copies the file a b c to existing dir a b c creating any missing intermediate direc tories CONTENTS 16 p preserve Preserve the original files owner group permissions and times tamps r Copy directories recursively copying all non directories as if they were regular files s symbolic link Make symbolic links instead of copies of non directories All source filenames must be absolute starting with unless the destination files are in the current directory This option produces an error message on systems that do not support symbolic links u update Do not copy a nondirectory that has an existing destination with the same or newer modification time v verbose Print the name of each file before copying it x one file system Skip subdirectories that are on different filesystems from the one that the copy started on R recursive Copy directories recursively help Print a usage message on standard output and exit successfully version Print version information on standard output then exit successfully S suffix backup suffix Th
116. gain How do I add text to the end of a line a You ll probably realise that the direction keys will not bring the cursor beyond the last character in the line Typing the letter a for append will put you in insert mode just to the right of the cursor If you don t want to have to move to the end of the line to add something to the end of the line type A in capitals This will get you to the end of the current line no matter where in the line you were But moving a character at a time is too slow CONTENTS 169 Typing w in command mode moves you to the start of the next word and b does the reverse Typing gets you to the beginning of the line and to the end If you are familiar with regular expressions outside the scope of this document you ll find them easy to remember lt Ctrl gt U lt Ctrl gt D Control U and Control D move about half a screen up or down respectively a 1 gets you to the first line in the buffer It should be obvious by now that you can replace 1 with any line number you care to choose gets you to the last line in the buffer I A If you re inserting text at the beginning or end of lines the command I is similar to i insert at beginning of line and A is similar to a append at end of line I can t delete text in insert mode In insert mode you can delete text that you ve typed in the current line in the current insertion That is if you hit the escape key and
117. he system There are three basic commands to manipulate these file attributes in Linux chown to change the ownership of the files chgrp is used to change the group attributes And chmod is used to change permissions or modes of files and directories There are three attributes for each level The permissions have slightly different meaning in directories than they do for regualar files Read If the read permis sion is set on a file the user can look at the contents of the file A user how has read permissions for a directory can list what files are in that directory To get detailed information ls 1 about the files in the directory the execute per missions on the directory must also be set for that user The read permissions on the files themselves determine if the user can read the contents of the files in the directory Write File write permissions determine whether the user will be allowed to modify the file Write permissions on directories determine whether the user will be able to change files in the directory That is whether the user will be able to add or remove files from the directory The ability to remove files is determined by the permissions on the individual files in the directory Execute If the execute permission is set for the user that user can use the file as a Linux system command Execute permissions on a directory means that a user can change directories to that directory and copy files from that directories provi
118. ical access to the console keyboard can shut the system down To prevent this shutdown can check to see if an authorized user is logged in on one of the virtual consoles If shutdown is called from init 8 it checks to see if the file etc shutdown allow is present It then compares the login names in that file with the list of people that are logged in on a virtual console from var run utmp Only if one of those authorized users or root is logged in it will proceed Otherwise it will write the message shutdown no authorized users logged in to the physical system console The format of etc shutdown allow is one user name per line Empty lines and comment lines prefixed by a are allowed Currently there is a limit of 32 users in this file FILES fastboot etc inittab etc init d halt etc init d reboot etc shutdown allow BUGS Not really a bug but most users forget to give the time argument and are then puzzled by the error message shutdown produces The time argument is mandatory in 90 percent of all cases this argument will be the word now AUTHOR Miquel van Smoorenburg miquels eistron nl SEE ALSO fsck 8 init 1 halt 8 reboot 8 EXAMPLES su NAME su run a shell with substitute user and group IDs CONTENTS 80 SYNOPSIS su flmp c command s shell login fast preserve environment command command shell shell help version user arg DESCRIPTION This documentation is n
119. ical or lexicographic order E g ps jax sort uid ppid pid help Get a help message that summarizes the usage and gives a list of sup ported sort keys This list may be more up to date than this man page version Display version and source of this program SORT KEYS Note that the values used in sorting are the internal values ps uses and not the cooked values used in some of the output format fields CONTENTS 72 SHORT LONG DESCRIPTION c cmd simple name of executable C cmdline full command line f flags flags as in long format F field g pgrp process group ID G tpgid controlling tty process group ID j cutime cumulative user time J cstime cumulative system time k utime user time K stime system time m min_flt number of minor page faults M maj_flt number of major page faults n cmin flt cumulative minor page faults N cmaj_flt cumulative major page faults o session session ID p pid process ID P ppid parent process ID r rss resident set size R resident resident pages s size memory size in kilobytes S share amount of shared pages t tty the minor device number of tty T start_time time process was started U uid user ID number u user user name v vsize total VM size in bytes y priority kernel scheduling priority CONTENTS 73 FIELD DESCRIPTIONS PRI This is the counter field in the task struct It is the time in HZ of the process s possible timeslice NI Standard unix nice value a positive va
120. ill generally not need to change them at all unless your terminal does not use ISO 6429 color sequences but a different system If your terminal does use ISO 6429 color codes you can compose the type codes i e all except the Ic rc and ec codes from numerical commands separated by semicolons The most common commands are 0 to restore default color 1 for brighter colors 4 for underlined text 5 for flashing text 30 for black foreground 31 for red foreground 32 for green foreground 33 for yellow or brown foreground CONTENTS 49 34 for blue foreground 35 for purple foreground 36 for cyan foreground 37 for white or gray foreground 40 for black background 41 for red background 42 for green background 43 for yellow or brown background 44 for blue background 45 for purple background 46 for cyan background 47 for white or gray background Not all commands will work on all systems or display devices A few terminal programs do not recognize the default end code properly If all text gets colorized after you do a directory listing try changing the no and fi codes from 0 to the numerical codes for your standard fore and back ground colors BUGS On BSD systems the s option reports sizes that are half the correct values for files that are NFS mounted from HP UX systems On HP UX systems it reports sizes that are twice the correct values for files that are NFS mounted from BSD systems This is due to a
121. imit of 11 parameters that can be associated with each keyword though you can reuse a keyword for additional parameters if the setup function supports it First the kernel checks to see if the argument is any of the special arguments root ro rw or debug Then it walks a list of setup functions contained in the bootsetups array to see if the specified argument string such as foo has been associated with a setup function foo_setup for a particular device or part of the kernel If you passed the kernel the line foo 3 4 5 6 bar then the kernel would search the bootsetups array to see if foo was registered If it was then it would call the setup function associated with foo foo_setup and hand it the integer arguments 3 4 5 and 6 as given on the kernel command line and also hand it the string argument bar Anything of the form foo bar that is not accepted as a setup function above is then interpreted as an environment variable to be set An example would be to use TERM vt100 or BOOT_IMAGE vmlinuz bak as a boot argument These environment variables are typically tested for in the initialization scripts to enable or disable a wide range of things Any remaining arguments that were not picked up by the kernel and were not interpreted as environment variables are then passed onto process one which is usually the init program The most common argument that is passed to the init process is th
122. ined and may be inaccurate or incomplete The Texinfo documentation is now the authoritative source This manual page documents the GNU version of df df displays the amount of disk space available on the filesystem containing each file name argument If no file name is given the space available on all currently mounted filesystems is shown Disk space is shown in 1K blocks by default unless the environment variable POSIXLY_CORRECT is set in which case 512 byte blocks are used If an argument is the absolute file name of a disk device node containing a mounted filesystem df shows the space available on that filesystem rather than on the filesystem containing the device node which is always the root filesystem This version of df cannot show the space available on unmounted filesystems because on most kinds of systems doing so requires very nonportable intimate knowledge of filesystem structures OPTIONS a all Include in the listing filesystems that have 0 blocks which are omit ted by default Such filesystems are typically special purpose pseudo filesystems such as automounter entries On some systems filesystems CONTENTS 18 of type ignore or auto are also omitted by default and included in the listing by this option i inodes List inode usage information instead of block usage An inode short k ZT t X X lt for index node is a special kind of disk block that contains i
123. ing are valid ONLY on ideO and the defaults for the base ctl ports must not be altered ide0 dtc2278 probe support DTC2278 interface ide0 ht6560b probe support HT6560B interface ideo cmd640_vlb REQUIRED for VLB cards with the CMD640 chip not for PCI automatically detected ide0 qd6580 probe support qd6580 interface ideO alil4xx probe support alil4xx chipsets ALI M1439 M1445 ideO umc8672 probe support umc8672 chipsets CONTENTS 122 Other Drivers There are additional drivers and associated boot arguments for old MFM RLL Standard ST 506 disk drives XT disk drives sound devices old CD ROM drives ISDN serial devices ethernet devices floppy disk drives bus mice printer drivers and parallel ports If you need information on those drivers see the HOWTO referenced below For a more detailed discussion of this topic see the BootPrompt HOWTO http www ibiblio org mdw HOWTO BootPrompt HOWTO html Single User Mode The comman linux single during the boot put your computer into runlevel 1 or single user mode You will be logged in as root and you re not supposed to enter any passwords as you normally are A backdoor into Linux for you as root so that you have a chance to correct any errors that might occur Here are some examples Lets say that you run kdm gdm or xdm via etc inittab If you by accident make an error in the setup of X or inittab the result might be that you never get to the graphical
124. is allows installation or upgrading even if the operating systems of the binary RPM and host don t match Conflicting Files RPM keeps track of conflicts with already installed packages and will alert you of those conflicts Under normal circumstances unless the installer overrides with the force option RPM will refuse to install the package CONTENTS 147 Unresolved Dependencies RPM knows about other software that the package being installed depend upon It checks the system database of installed packages and unless the installer overrides it with the nodeps option issues a dependancy warning and does not install the package It is generally a bad idea to override this dependancy check unless you installed the dependant package as a compiled binary or know of some other inormation Removing Packages with RPM The command line for removing RPMs is rpm e lt package_file gt There are options for removing packages allmatches Remove all versions of the package which match lt package_name gt Normally an error is issued if lt package name gt matches multiple packages noscripts Don t execute the preuninstall or postuninstall scripts notriggers Don t execute scripts which are triggered by the removal of this package nodeps Don t check dependencies before uninstalling the packages test Don t really uninstall anything just go through the motions vv option nodeps Don t check for broken
125. ithout any spaces For example ether 9 0x300 0xd0000 0xd4000 eth0 root dev hdal RIGHT ether 9 0x300 0xd0000 0xd4000 eth0 root dev hdal WRONG LILO is the most common boot loader on Linux systems Typically the boot loader will print LILO to the screen then wait a few seconds for input With no input it will boot to the default system Typical system labels that people use in the LILO configuration files are linux and Windows and msdos If you want to pass arguments to the kernel this is the place to do it For example LILO linux root dev hdal LILO comes with excellent documentation as discussed above The LILO ap pend command is usefull if you want to add a boot time argument as a per manent addition to the LILO config file You simply add something like append hd 64 32 202 to the etc lilo conf file to pass paramters about hard drive geometry for example It can either be added at the top of the config file making it apply to all sections or to a single system section by adding it inside an image section Please see the LILO documentation for a more complete description How the kernel sorts arguments Most boot arguments take the form name value_1 value_2 value_11 CONTENTS 116 name is a unique keyword that is used to identify what part of the kernel the associated values if any are to be given to Multiple boot args are just a space separated list of the above format There is a l
126. itten by Branko Lankester lt lankeste fwi uva nl gt Michael K Johnson lt johnsonm red hat com gt re wrote it significantly to use the proc filesystem changing a few things in the process Michael Shields lt mjshield nyx cs du edu gt added the pid list feature Charles Blake lt chlake bbn com gt added multi level sorting the dirent style library the device name to num ber mmaped database the approximate binary search directly on System map and many code and doc umentation cleanups David Mossberger Tang wrote the generic BFD support for psupdate Michael K Johnson lt johnsonm red hat com gt is the current maintainer Please send bug reports to lt procps bugs redhat com gt CONTENTS 75 EXAMPLES joe localhost ps PID TTY STAT TIME COMMAND 3485 1 S 0 00 xterm sb 3509 p1 S 0 00 bash 16910 2 S 0 00 sbin mingetty tty2 17024 p4 S 0 00 bash 17076 3 S 0 00 mingetty 17077 4 S 0 00 mingetty 17078 5 S 0 00 mingetty 17079 6 S 0 00 mingetty 17647 p4 R 0 00 ps rm NAME rm remove files SYNOPSIS rm dfirvR directory force interactive recursive help version verbose name DESCRIPTION This documentation is no longer being maintained and may be inaccurate or incomplete The Texinfo documentation is now the authoritative source This manual page documents the GNU version of rm rm removes each specified file By default it does not remove directories If a file is unwrita
127. k view of a shell script If you are running a Red Hat system you can view the file on your own system cat usr bin run parts bin bash run parts concept taken from Debian keep going when something fails set e if lt 1 then echo Usage run parts lt dir gt exit 1 fi if d 1 then echo Not a directory 1 exit 1 fi for iin 1 do d i amp amp continue if x i then i fi done exit 0 CONTENTS 164 The disection James Jim G Sack wrote this explanation of the program The explanations are all covered in man bash or the bash reference manual keep going when something fails set e Normally a shell script does not exit on a command error The e option forces exit on error executing any command not otherwise tested So the e option reverts to default just in case the e was in effect when this shell was invoked Hence the keep going when something fails Admittedly the action of the is easy to overlook in reading man bash if lt 1 then echo Usage run parts lt dir gt exit 1 fi if the argument count of args passed to this shell script is less than 1 then give a usage message and exit without doing anything else The fi is the ending keyword for the if command syntax The semi colon usage may be understood by giving the full syntax ignoring elif else variants if condition then command list fi plus expl
128. l d and login as the new user you created Setting and changing a password From time to time you may have reason to change your password you use the passwd command to change you password Here s what a typical session would look like joe localhost passwd changing password for joe current Unix password New UNIX password Retype new UNIX password passwd all authentication tokens updated successfully Logging out There are a couple of methods to log out of your Linux systems You can either use the exit command or use the key combination lt Ctrl gt d Hold down the Ctrl and d key at the same time to log out CONTENTS 4 Virtual Consoles A useful feature of Linux is the virtual consoles When you first log into a Linux system you are on the first virtual console of the system On a standard Linux system you have eight virtual consoles This is configurable but we won t discuss that right now Using the three key combination lt Ctrl gt lt Alt gt F n where F n is one of the function keys between F1 and F8 you can move between these virtual consoles If you are in X when you do this F7 becomes your X session and you will see the error output from the X server in virtual console 1 VC1 when you go back to it Virtual consoles allow you to do multiple things at the same time in console mode File System On some single user operating systems placement of files and directories is at the whim
129. l export DISPLAY 0 0 to allow you to run X applications as root while logged into X as a regular user Of course you will still have to cd usr src linux so you are in the right directory then make xconfig will start the X interface to configure the kernel Compiling the Kernel Now you are ready to do the kernel compile Here are the commands root localhost make dep root localhost make clean root localhost make bzImage root localhost make modules root localhost make modules_install However you can save a little time and simplify by stringing the commands to gether There are two ways to string commands together on the command line with the semi colon or the double ampersands amp amp The semi colons don t impose any conditions on the execution of the next command in the sequence This could potentially waste time and cause unnecessary complications Po tentially the kernel compile step could fail but the modules build and install The double ampersand says only execute the next command in the sequence if the previous command succeeded So in the example above the make modules command would fail if the make bzImage command wasn t successful Here s what the command line would look like if you string the commands together root localhost make dep amp amp make clean amp amp make bzImage amp amp make modules amp amp make modules_install LILO The new kernel is built and is in
130. lete the entire command line or cancel the command if the command line is empty If you have changed your line kill character in Unix to some thing other than U that character is used instead of U KEY BINDINGS You may define your own less commands by using the program lesskey 1 to create a lesskey file This file specifies a set of command keys and an action as sociated with each key You may also use lesskey to change the line editing keys see LINE EDITING and to set environment variables If the environment variable LESSKEY is set less uses that as the name of the lesskey file Other wise less looks in a standard place for the lesskey file On Unix systems less looks for a lesskey file called HOME less On MS DOS systems less looks for a lesskey file called HOME _less and if it is not found there then looks for a lesskey file called _less in any directory specified in the PATH environment variable On OS 2 systems less looks for a lesskey file called HOME less ini and if it is not found then looks for a lesskey file called less ini in any direc tory specified in the INIT environment variable and if it not found there then looks for a lesskey file called less ini in any directory specified in the PATH environment variable See the lesskey manual page for more details INPUT PREPROCESSOR You may define an input preprocessor for less Before less opens a file it first gives yo
131. ll users time When to shutdown warning message Message to send to all users The time argument can have different formats First it can be an absolute time in the format hh mm in which hh is the hour 1 or 2 digits and mm is the minute of the hour in two digits Second it can be in the format m in which m is the number of minutes to wait The word now is an alias for 0 The f flag means reboot fast This only creates an advisory file fastboot which can be tested by the system when it comes up again The boot rc file can test if this file is present and decide not to run fsck 1 since the system has been shut down in the proper way After that the boot process should remove fast boot The F flag means force fsck This only creates an advisory file forcefsck which can be tested by the system when it comes up again The boot rc file can test if this file is present and decide to run fsck 1 with a special force flag so that even properly unmounted filesystems get checked After that the boot process should remove forcefsck CONTENTS 79 The n flag causes shutdown not to call init but to kill all running processes it self shutdown will then turn off quota accounting and swapping and unmount all filesystems ACCESS CONTROL shutdown can be called from init 8 when the magic keys CTRL ALT DEL are pressed by creating an appropriate entry in etc inittab This means that everyone who has phys
132. lls this iso9660 International Stan dard Organization ISO created this standard to use on CD ROMs and every CD that stores data uses this Microsoft implemented Joliet Exten sion so that a CD can hold music and video while still being compatible with regular CD player i e BackStreet Boy s album EveryBody JFS provides fast file system restart in the event of a system crash Using database journaling techniques JFS can restore a file system to a consis tent state in a matter of seconds or minutes versus hours or days with non journaled file systems IBM s journaled file system technology cur rently used in IBM enterprise servers is designed for high throughput server environments key to running intranet and other high performance e business file servers Maximum file system size is 4 to 32 petabytes depending no the block size Maximum files size also depends upon block size from 512 Terabytes to 4 petabytes NTFS NT filesystem Linux calls this ntfs Used by Windows NT Linux only can do read only access to this filesystem at this moment one of the reasons is that the security features Windows NT has that are not compatible with Unix Linux Windows NT can have two filesystems FAT and NTFS If NT is running on FAT Linux can access the NT partition as a FAT VFAT filesystem NFS Network Filesystem Linux calls this nfs Network filesystem was de veloped by Sun Microsystems and still widely used to a
133. locked It is possible to shut the system down immediately or after a specified delay All processes are first notified that the system is going down by the signal SIGTERM This gives programs like vi 1 the time to save the file being edited mail and news processing programs a chance to exit cleanly etc shutdown does its job by signalling the init process asking it to change the runlevel Runlevel 0 is used to halt the system runlevel 6 is used to reboot the system and runlevel 1 is CONTENTS 78 used to put to system into a state where administrative tasks can be performed this is the default if neither the h or r flag is given to shutdown To see which actions are taken on halt or reboot see the appropriate entries for these runlevels in the file etc inittab OPTIONS t sec Tell init 8 to wait sec seconds between sending processes the warning and the kill signal before changing to another runlevel k Don t really shutdown only send the warning messages to everybody r Reboot after shutdown h Halt after shutdown n DEPRECATED Don t call init 8 to do the shutdown but do it ourself The use of this option is discouraged and its results are not always what you d expect f Skip fsck on reboot F Force fsck on reboot c Cancel an already running shutdown With this option it is of course not pos sible to give the time argument but you can enter a explanatory message on the command line that will be sent to a
134. login because the bootprocess never get that far That s when linux single is there to help you It boots Linux to a root prompt so that you can correct the errors and reboot the computer You re running as root you know better don t you and you leave a process running that logs through syslog It fills up your log file and in turn your partition Now you can t log in In single user mode you can fix it You forgot your root password and need to reset it If you are using LILO at the LILO boot prompt if you are using the graphical LILO press Ctrl x to exit the graphical screen and go to the boot prompt boot linux single The GRUB boot loader doesn t have a default boot prompt You can choose e when the menu displays to edit the boot paramters select the line that starts with kernel for the kernel you want to boot Go to the end of the line and type single as a seperate word press the Spacebar and then type single Press Enter to exit edit mode Back at the GRUB screen type b to boot into single user mode You might find it simpler to edit grub conf and add a single user login menu item similar to this title Single User Mode root hd0 0 CONTENTS 123 kernel vmlinuz 2 4 20 8 single rw root LABEL hdc ide scsi initrd initrd 2 4 20 8 img Of course you don t want to copy this verbatim since your system will be different This is only an example Starting the System System 5 init
135. ls l rw rw rw 1 joe joe 0 Mar 26 19 22 firstfile rw rw rw 1 joe joe 0 Mar 26 19 22 fourfile rw rw rw 1 joe joe 0 Mar 26 19 22 lastfile rw rw rw 1 joe joe 0 Mar 26 19 22 onefile joe localhost rm onefile rm remove onefile y joe localhost ls l rw rw rw 1 joe joe 0 Mar 26 19 22 firstfile rw rw rw 1 joe joe 0 Mar 26 19 22 fourfile rw rw rw 1 joe joe 0 Mar 26 19 22 lastfile rmdir NAME rmdir remove empty directories CONTENTS 77 SYNOPSIS rmdir p parents help version dir DESCRIPTION This documentation is no longer being maintained and may be inaccurate or incomplete The Texinfo documentation is now the authoritative source This manual page documents the GNU version of rmdir rmdir removes each given empty directory If any non option argument does not refer to an existing empty directory it is an error OPTIONS p parents Remove any parent directories that are explicitly mentioned in an argument if they become empty after the argument file is removed help Print a usage message on standard output and exit successfully version Print version information on standard output then exit successfully EXAMPLES shutdown NAME shutdown bring the system down SYNOPSIS sbin shutdown t sec rkhnefF time warning message DESCRIPTION shutdown brings the system down in a secure way All logged in users are notified that the system is going down and login 1 is b
136. lue means less cpu time SIZE Virtual image size size of text data stack RSS Resident set size kilobytes of program in memory WCHAN Name of the kernel function where the process is sleeping with the sys stripped from the function name If etc psdatabase does not exist it is just a hex number instead STAT Information about the status of the process The first field is R for runnable S for sleeping D for uninterruptible sleep T for stopped or traced or Z for a zombie process The second field contains W if the process has no resident pages The third field is N if the process has a positive nice value NI field TT Controlling tty PAGEIN Number of major page faults page faults that cause pages to be read from disk including pages read from the buffer cache TRS Text resident size SWAP Kilobytes or pages if p is used on swap device SHARE Shared memory UPDATING This proc based ps works by reading the files in the proc filesys tem mounted on proc This ps does not need to be suid kmem or have any privileges to run Do not give this ps any special permissions You will need to update the etc psdatabase file by running usr sbin psupdateto get meaningful information from the WCHAN field This should be done every time you compile a new kernel You should also run ps as root once and then any time the tty devices in the dev directory change As of procps 1 00 ps top read System map directly if it
137. m the environment variable VISUAL if defined or EDITOR if VI SUAL is not defined or defaults to vi if neither VISUAL nor EDITOR is defined See also the discussion of LESSEDIT under the section on PROMPTS below shell command Invokes a shell to run the shell command given A percent sign in the command is replaced by the name of the current file A pound sign is replaced by the name of the previously examined file I repeats the last shell command with no shell command simply invokes a shell On Unix systems the shell is taken from the environment variable SHELL or defaults to sh On MS DOS and OS 2 systems the shell is the normal command processor lt m gt shell command lt m gt represents any mark letter Pipes a section of the input file to the given shell command The section of the file to be piped is between the first line on the current screen and the position marked by the letter lt m gt may also be or to indicate beginning or end of file respectively If lt m gt is or newline the current screen is piped CONTENTS 28 s filename Save the input to a file This only works if the input is a pipe not an ordinary file OPTIONS Command line options are described below Most options may be changed while less is running via the command Options are also taken from the environment variable LESS For example to avoid typing less options each time less is invok
138. mat is described in no floppy Do not probe any floppy drive This option has no effect if the option device map is specified probe second floppy Probe the second floppy drive If this option is not specified the grub shell does not probe it as that sometimes takes a long time If you specify the device map file the grub shell just ignores this option config file FILE Read the configuration file FILE instead of boot grub grub conf The format is the same as the normal GRUB syntax See Note Filesys tem for more information boot drive DRIVE Set the stage2 BOOT_DRIVE to DRIVE This argu ment should be an integer decimal octal or hexadecimal install partition PAR Set the stage2 INSTALL_PARTITION to PAR This argument should be an integer decimal octal or hexadecimal no config file Do not use the configuration file even if it can be read no curses Do not use the curses interface even if it is available batch This option has the same meaning as no config file no curses read only Disable writing to any disk hold Wait until a debugger will attach This option is useful when you want to debug the startup code CONTENTS 114 General commands Commands usable both in the menu and in the command line bootp Initialize a network device via BOOTP color Color the menu interface device Specify a file as a drive dhcp Initialize a network device via DHCP hide Hide
139. ms If a destination file is unwritable the standard input is a tty and the f or force option is not given mv prompts the user for whether to overwrite the file If the response does not begin with y or Y the file is skipped OPTIONS b backup Make backups of files that are about to be removed f force Remove existing destination files and never prompt the user i interactive Prompt whether to overwrite each destination file that already exists If the response does not begin with y or Y the file is skipped u update Do not move a nondirectory that has an existing destination with the same or newer modification time v verbose Print the name of each file before moving it help Print a usage message on standard output and exit successfully version Print version information on standard output then exit successfully S suffix backup suffix The suffix used for making simple backup files can be set with the SIMPLE_BACKUP_SUFFIX environment variable which can be overridden by this option If neither of those is given the default is as it is in Emacs V version control numbered existing simple The type of backups made can be set with the VERSION_CONTROL environment variable which can be overridden by this option If VERSION_CONTROL is not set and this option is not given the default backup type is existing The value of the VERSION_CONTROL environment variable and the a
140. n zip to try decompression on all given files regardless of suffix as in gunzip S for MSDOS Previous versions of gzip used the z suffix This was changed to avoid a conflict with pack 1 t test Test Check the compressed file integrity v verbose Verbose Display the name and percentage reduction for each file compressed or decompressed V version Version Display the version number and compilation options then quit fast best Regulate the speed of compression using the specified digit where 1 or fast indicates the fastest compression method less com pression and 9 or best indicates the slowest compression method best CONTENTS 155 compression The default compression level is 6 that is biased towards high compres sion at expense of speed tar tar tricks Upgrading Software Upgrading Libraries Upgrading the Compiler Upgrading Other Software Building a New Kernel Why Compile a Kernel There are any number of reasons for building a custom kernel e You have found some new package that requires feature only available in the newer kernel e You have a special device on your system that is only supported by the newer kernel e You heard it was a cool thing to do so you want to try e You want to tune options in your kernel to improve the performance of your system e You heard that the newest kernel version is the fastest ever and you want to find out for yoursel
141. n hitting X you are again prompted whether you would like to save the file as noted above upone hiting y you will be given the Command Input Line with a blank file name Type in the file name you would like to save the file if you hit enter with no file name you will be brought back to the Pico editor with Cancled in the Notify window Exit Cancled will be displayed of C is hit at this point Saving the file WriteOut O Will save the file Saving a pre existing file Saving a new file Justifying text J justify your text You re editing a file and you don t have word wrap on You notice a typographical error or deleted some text Pico has of course previously word wraped your text and you don t like the results U will undo what you just did You can go back and forth between J and U more on U later Inserting a file R read a file Want to add an allready exiting file to the file your currently editing Use R Place the cursor where you want to add a file and hit R At the comamnd prompt type in the name of the file you want to insert It says Home directory but it really means the current directory where you started Pico If you want to include a file not in the current directory just use the path like myfile or tmp myfile or myfile If the file is in the current directory just type myfile Searching W Where is CONTENTS Moving about Previous Page Next
142. nctions are easy for an end user to use e Rich functionality for OS experts designers e Compatibility for booting FreeBSD NetBSD OpenBSD and GNU Linux Proprietary OS s such as Windows 9x NT 2000 XP and OS 2 are sup ported via a chain loading function In addition to the requirements above GNU GRUB has the following features e Support multiple executable formats e Support non Multiboot OS s e Load multiple modules Support a human readable configuration file e Menu interface Flexible command line interface e Support multiple filesystem types e Support automatic decompression CONTENTS 109 e Access data on any installed device e Geometry translation independent e Detect all installed RAM e Support Logical Block Address LBA mode e Download OS images from a network e Support diskless systems e Support remote terminals Sounds like the swiss army knife of boot loaders One of the important features in GRUB is flexibility GRUB understands filesys tems and kernel executable formats so you can load an arbitrary operating sys tem the way you like without recording the physical position of your kernel on the disk Thus you can load the kernel just by specifying its file name and the drive and the partition where the kernel resides To let GRUB know the drive and the file name you can either type in them manually via the command line interface or use the nice menu interface through which y
143. ndicate the current extended BSD style of command line arguments For now ps will give you a warning if you use a for a short option but it will still work If you have shell scripts which use BSD style arguments to ps take heed of the warning and fix them or else your scripts will fail to function correctly at some point in the future If you want to turn off the warnings set the 1 WANT_A BROKEN _PS environ ment variable There are also some long options in GNU style see below for those 1 long format u user format gives user name and start time j jobs format pgid sid s signal format v vm format m displays memory info combine with p flag to get number of pages f forest family tree format for command line a show processes of other users too x show processes without controlling terminal S add child cpu time and page faults c command name from task_struct e show environment after command line and w wide output don t truncate command lines to fit on one line To be exact every w that is specified will add another possible line to the output If the space isn t needed it isn t used You may up to 100 w s h no header r running procs only n numeric output for USER and WCHAN CONTENTS 71 txx only procs with controlling tty xx for xx you may use either the name of a device file under dev or that name with either tty or cu sliced off This is the reverse heuristic that
144. ne of the following options must be used A catenate concatenate append tar files to an archive c create create a new archive d diff compare find differences between archive and file system delete delete from the archive not for use on mag tapes r append append files to the end of an archive t list list the contents of an archive u update only append files that are newer than copy in archive x extract get extract files from an archive CONTENTS 84 OTHER OPTIONS atime preserve don t change access times on dumped files b block size N block size of Nx512 bytes default N 20 B read full blocks reblock as we read for reading 4 2BSD pipes C directory DIR change to directory DIR checkpoint print directory names while reading the archive f file HOSTNAME F use archive file or device F default dev rmt0 force local archive file is local even if has a colon F info script F new volume script F run script at end of each tape implies M G incremental create list extract old GNU format incremental backup g listed incremental F create list extract new GNU format incremental backup h dereference don t dump symlinks dump the files they point to i ignore zeros ignore blocks of zeros in archive normally mean EOF ignore failed read don t exit with non zero status on unreadable files k keep old files keep existing files don t
145. netctl usleep requires the chkconfig package chkconfig provides the basic chkconfig tool and the curses wrapper program CONTENTS 129 ntsysv both mentioned above man pages are chkconfig ntsysv redhat config packages provides the gui Runlevel Editor program and some help text a man page exists for redhat config packages init and inittab Berkeley init Shutting Down the System If the Linux system is not properly shutdown the file system can be corrupted How corrupted depends upon what programs were being run and whether the hard drives were synced before shutdown Many time accidental shutdowns can be recovered but sometimes not It is better to know the proper methods than to risk file corruption The shutdown command is the best method to insure programs are closed files are saved and hard drives are properly synced To shutdown and reboot perhaps to start another OS gasp shutdown r time time can be now or a time in minutes Many Linux systems trap the lt Ctrl gt lt Alt gt lt Del gt key combination aka Three Finger Salute and alias it to shutdown r now To shutdown before electri cally turning off the system you might shutdown h now you can substitute a number and specify time in minutes System Management Managing User Accounts Jim Sack jsack dornfeld com The passwd File Jim Sack jsack dornfeld com The group File Jim Sack jsack dornfeld com Adding User Accounts
146. nformation about a file such as its owner permissions timestamps and location on the disk kilobytes Print sizes in 1K blocks instead of 512 byte blocks This overrides the environment variable POSIXLY_CORRECT P portability Use the POSIX output format This is like the default format except that the information about each filesystem is always printed on exactly one line a mount device is never put on a line by itself This means that if the mount device name is more than 20 characters long as for some net work mounts the columns are misaligned print type Print a type string for each filesystem Any such printed filesys tem type name may be used as an argument to either of the type or exclude type options type fstype Limit the listing to filesystems of type fstype Multiple filesys tem types can be shown by giving multiple t options By default all filesystem types are listed exclude type fstype Limit the listing to filesystems not of type T print type Print a type string for each filesystem Any such printed filesystem type name may be used as an argument to either of the type or exclude type options type fstype Limit the listing to filesystems of type fstype Multiple filesys tem types can be shown by giving multiple t options By default all filesystem types are listed exclude type fstype Limit the listing to filesystems not of type fstype Multiple filesystem types can be shown by giving mul
147. ng with that but this is larger than 1024 and could in certain setups cause problems with 1 software that runs at boot time e g old versions of LILO 2 booting and partitioning software from other OSs e g DOS FDISK 08 2 FDISK Disk dev hdb 255 heads 63 sectors 1653 cylinders Units cylinders of 16065 512 bytes dev hdbl 1 413 2441406 83 Linux dev hdb2 414 827 2441406 83 Linux dev hdb3 828 1240 2441406 83 Linux dev hdb4 1241 1653 2441406 83 Linux Command m for help t Partition number 1 4 2 Hex code type L to list codes 82 Changed system type of partition 2 to 82 Linux swap CONTENTS 139 Command m for help w The partition table has been altered Calling ioctl to re read partition table fdisk l dev hdb Disk dev hdb 255 heads 63 sectors 1653 cylinders Units cylinders of 16065 512 bytes dev hdbl 1 413 2441406 83 Linux dev hdb2 414 827 2441406 82 Linux swap dev hdb3 828 1240 2441406 83 Linux dev hdb4 1241 1653 2441406 83 Linux mkswap dev hdb mkswap dev rd c0d1p2 Setting up swapspace version 1 size 2499999 kB Enabling Swap Space So now we need to add the swap partition to etc fstab so it s automatically enabled the next time we boot We add the following line dev hdb2 swap swap defaults 00 And we can enable the swap partition without rebooting by doing the following swapon dev hdb2 Disabling Swap Space To disable swap you just use the swapoff comman
148. nnections xdm eg 6 2345 respawn sbin mingetty tty6 ctrlaltdel process to be executed when the CTRL ALT DEL key combination three finger salute is pressed Typically some shutdown procedure This line in etc inittab instructs sbin init what to do next si sysinit etc re d re sysinit rc sysinit 1 10 11 12 13 14 15 16 17 SOP ae SOP CORY reads sources dev devfsd checks to see if we re running devfs and starts the devfsd daemon check to see if it exists then reads etc sysconfig network for instructions on setting the hostname and starting networking reads etc init d functions for instructions for setting up locale and for function definitions checks to see if this will be a graphical boot and prepares for it checks etc inittab and starts mgetty on configured virtual consoles set console fonts prints a banner to the console mounts the proc filesystem unmounts the startup ramdisk configures kernel paramters sets the system clock read he configuration and maps the keyboard for the terminals and console sets the hostname initializes USB devices and HID devices like USB keyboard and mouse and required USB storage runs fsck on the file systems checks for filesystem quotas and updates quotas on the root filesystem checks for ISP plug n play devices and configures them CONTENTS 125 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
149. non filename text fi 0 Regular file di 32 Directory In 36 Symbolic link pi 31 Named pipe FIFO so 33 Socket bd 44 37 Block device cd 44 37 Character device CONTENTS 48 ex 35 Executable file mi none Missing file defaults to fi or none Orphaned symbolic link defaults to In Ic e Left code rc m Right code ec none End code replaces Ic no rc You only need to include the variables you want to change from the default File names can also be colorized based on filename extension This is specified in the LS_COLORS variable using the syntax ext string For example using ISO 6429 codes to color all C language source files blue you would specify c 34 This would color all files ending in c in blue 34 color Control characters can be written either in C style escaped notation or in stty like notation The C style notation adds e for Escape _ for a normal space character and for Delete In addition the escape character can be used to override the default interpretation of and Each file will be written as lt lc gt lt color code gt lt rc gt lt file name gt lt ec gt If the lt ec gt code is undefined the sequence lt lc gt lt no gt lt rc gt will be used instead This is generally more convenient to use but less general The left right and end codes are provided so you don t have to type common parts over and over again and to support weird terminals you w
150. nu root hd0 0 makeactive chainloader 1 For loading DOS if Windows NT is installed chainload bootsect dos This boots Windows Creating a GRUB boot floppy To create a GRUB boot floppy you need to take the files stagel and stage2 from the image directory and write them to the first and the second block of the floppy disk respectively Caution This procedure will destroy any data currently stored on the floppy On a Linux that is done with the following commands cd usr share grub i386 pc dd if stagel of dev fd0 bs 512 count 1 0 records in m m 0 records out dd if stage2 of dev fd0 bs 512 seek 1 153 1 records in 153 1 records out A GRUB boot floppy is a great recovery tool CONTENTS 113 The grub shell You can use the command grub for installing GRUB under your operating systems and for a testbed when you add a new feature into GRUB or when fix a bug grub is almost the same as the Stage 2 and in fact it shares the source code with the Stage 2 and you can use the same commands in grub It is emulated by replacing BIOS calls with UNIX system calls and libc functions The command grub accepts the following options help Print a summary of the command line options and exit version Print the version number of GRUB and exit verbose Print some verbose messages for debugging purpose device map FILE Use the device map file FILE The for
151. nv t ext Default conv binary Since Linux 1 3 54 this option has no effect anymore And non binary set tings used to be very dangerous often leading to silent data corruption cruft If the high byte of the file length contains other garbage set this mount option to ignore the high order bits of the file length This implies that a file cannot be larger than 16MB The cruft option is set automatically if the entire CDROM has a weird size negative or more than 800MB It is also set when volume sequence numbers other than 0 or 1 are seen Mount options for minix None CONTENTS 65 Mount options for msdos See mount options for fat If the msdos file system detects an inconsistency it reports an error and sets the file system read only The file system can be made write able again by remounting it Mount options for ncp Just like nfs the ncp implementation expects a binary argument a struct ncp_mount_data to the mount system call This argument is constructed by ncpmount 8 and the current version of mount 2 6h does not know anything about ncp Mount options for nfs Instead of a textual option string parsed by the kernel the nfs file system expects a binary argument of type struct nfs_mount_data The program mount itself parses the following options of the form tag value and puts them in the structure mentioned rsize n wsize n timeo n retrans n acregmin n acregmax n acdirmin n acdirmax n ac
152. nzero integer optionally followed by one of the following characters to specify a different unit b 512 byte blocks k 1 kilobyte blocks m 1 megabyte blocks n N lines N Print first N lines q quiet silent Never print filename headers v verbose Always print filename headers help Print a usage message and exit with a status code indicating success version Print version information on standard output then exit CONTENTS 22 EXAMPLES head etc services services This file describes the various services that are available from the TCP IP subsystem It should be consulted instead of using the numbers in the ARPA include files or worse just guessing them Version etc services 2 00 04 30 93 Author Fred N van Kempen lt waltje uwalt nl mugnet org gt less NAME less opposite of more SYNOPSIS less less help less V less version less aBcCdeEfgGilmMnNqQrsSuU VwX b bufs h lines j line k keyfile 00 logfile p pattern P prompt t tag T tagsfile x tab y lines z lines Jemd filename DESCRIPTION Less is a program similar to more 1 but which allows backward movement in the file as well as forward movement Also less does not have to read the entire input file before starting so with large input files it starts up faster than text editors like vi 1 Less uses termcap or terminfo on some systems so it can
153. o longer being maintained and may be inaccurate or incomplete The Texinfo documentation is now the authoritative source This manual page documents the GNU version of su su allows one user to temporarily become another user It runs a shell with the real and effective user ID group ID and supplemental groups of USER If no USER is given the default is root the super user The shell run is taken from USER s password entry or bin sh if none is specified there If USER has a password su prompts for the password unless run by a user with real user ID 0 the super user By default su does not change the current directory It sets the environment variables HOME and SHELL from the password entry for USER and if USER is not the super user sets USER and LOGNAME to USER By default the shell is not a login shell If one or more ARGs are given they are passed as additional arguments to the shell su does not handle bin sh or other shells specially setting argv 0 to su passing c only to certain shells etc On systems that have syslog su can be compiled to report failed and optionally successful su attempts using sys log OPTIONS c COMMAND command COMMAND Pass COMMAND a single com mand line to run to the shell with a c option instead of starting an interactive shell f fast Pass the f option to the shell This probably only makes sense with csh and tcsh for which the f option prevents re
154. ogram isapnp takes the form of isapnp read_port reset skip_pci_scan verbose isapnp_reserve_dma takes the form of isapnp_reserve_dma n1 n2 n3 nN where nl nN are the DMA channel numbers to not use for PnP isapnp_reserve_io takes the form of isapnp_reserve_irq iol sizel io2 size2 ioN sizeN where ioX sizeX are I O start and length pairs of regions in I O space that are not to be used by PnP isapnp_reserve_irq takes the form of isapnp_reserve irgq n1 n2 n3 nN where nl nN are the interrupt numbers to not use for PnP CONTENTS 119 isapnp_reserve_mem takes the form of isapnp_reserve_mem mem1 sizel mem2 size2 memN sizeN where ioX sizeX are I O start and length pairs of regions in memory space that are not to be used by PnP kbd reset forces a reset at initialization time lockd udpport and lockd tcpport tell the kernel to use the given port numbers for NFS lockd operation for either UDP or TCP operation maxcpus number given with this argument limits the maximum number of CPUs activated in SMP mode max_scsi_luns allows you to set the maximum number of probed LUNs mca pentium prevent lock up on the test to detect the type of math chip coupling on microchannel machines md tell the kernel the multiple device layout nmi_watchdog hecks to see if the interrupt count is increasing indicating normal system activity and if it is not then it assumes that a processor is stuck and forces an error dump of diagn
155. on To edit your etc hosts file with word wrap disabled you would type pico w etc hosts As default I always start pico with the w option You can alias the command to always start pico with the w option At a command prompt alias mypico pico w 1 Now when you type mypico lt file_name gt pico will now will have word wrap disabled The alias command is covered in more detail in another section of this document More startup options As noted above pico is not really designed for a programming environment In the few cases where you might be compilling a program and would need to jump to a particular line number to find the error of a program the N option would come in handy where N would be the line number you want your cursor to start on Say your writing a program and your compiler complains about a syntax error on line 42 Starting Pico on the command line like this pico 42 myprogram c would start pico on with the cursor oon line 42 of your myprorgram c file v The v option will allow you to use pico as a file viewer instead of an editor The programs more and less doa fine job of viewing text files in there own right you can use Pico with the v option to do the same thing but with more of the ease of use of the Pico editor z Using ctrl z on some programs within Unix allows you to suspend that pro gram and return to the commmand line By default suspending Pico is disabled to enable the use of suspension within
156. on its standard output If the input pipe does not write any characters on its standard output then there is no replacement file and less uses the origi nal file as normal To use an input pipe make the first character in the LESSOPEN environment variable a vertical bar to sig nify that the input preprocessor is an input pipe For example on many Unix systems this script will work like the previous example scripts lesspipe sh CONTENTS 36 1 bin sh case 1 in Z uncompress c 1 2 gt dev null esac To use this script put it where it can be executed and set LESSOPEN lesspipe sh s When an input pipe is used a LESSCLOSE postprocessor can be used but it is usually not necessary since there is no replacement file to clean up In this case the replacement file name passed to the LESSCLOSE postprocessor 099 is NATIONAL CHARACTER SETS There are three types of characters in the input file e normal characters can be displayed directly to the screen e control characters should not be displayed directly but are expected to be found in ordinary text files such as backspace and tab e binary characters should not be displayed directly and are not expected to be found in text files A character set is simply a description of which characters are to be considered normal control and binary The LESSCHARSET environment variable may be used to select a character set Possible values for LESSCHARS
157. one else can only execute it 444 is r r r this is read only permission for everyone There is other information contained in the 10 characters at the beginning of a listing about special files for devices sockets symbols links etc However since this is primarily a text for beginners it will not be covered here Processes Linux is a true multi tasking operating system This means that it can run more than one task at a time on behalf of the user In Linux terminology each of the multiple tasks is called a process Each of these processes is running independantly with it s own allocated resources One of the first processes that the kernel spawns upon startup is the getty process which listens for and responds to a login Each time you ask the shell to run a command it forks a seperate process If you create a shell pipeline with the operarator each command component is a seperate process The comand line cat thisfile sort will generate two processes CONTENTS 99 one for each command These processes communicate through the pipe Some commands are internal to the shell and don t create any new processes A major purpose of the kernel is to provide control and support of the many programs that might want to use Central Processing Unit CPU at any one time Several programs or users may request access to the CPU at the same time The kernel must grant access to only one application at a time A process executes for
158. onfiguring the kernel those documents already exist on your system See the Kernel HOWTO on your system for more detailed information It s usually located in the HOWTO directory at usr doc HOWTO You must be in the top level kernel source directory usr src linux and you must be logged in as root to compile a kernel Again you have some choices make config You can answer questions in sequence from the command line by using the command root localhost make config One by one you will be asked a series of questions to determine the options for options to prepare the configuration file usr src linux config The drawback to make config is that if you make a wrong choice you will have to start over You can t go back with make config make menuconfig This is a curses based program similar to the graphical programs used to set up Red Hat Linux To begin simply root localhost make menuconfig This is a pretty straightfoward configuration interface that allows you to go forward and backward through the configuration questions until you have ev erything just right for your system You can even run make menuconfig in a virtual console make xconfig This is an X based program for setting up you configuration file before compiling your kernel There is a small trick for running make xconfig if like me you don t CONTENTS 158 run X as root Open an xterm and su to become root If you run are running the default bash shel
159. or security and automatic file compression Some beta quality variants of Ext2fs include Encrypted Ext2fs and journaling Ext2fs Ext3 The ext3 filesystem is a journaling extension to the standard ext2 filesys tem on Linux Journaling results in massively reduced time spent recover ing a filesystem after a crash and is therefore in high demand in environ ments where high availability is important not only to improve recovery times on single machines but also to allow a crashed machine s filesystem to be recovered on another machine when we have a cluster of nodes with a shared disk Maximum file system size 4 Terabytes Maximum file size 2 Gigabytes DOS FAT Linux calls these msdos umsdos vfat There are three variants MSDOS UMSDOS and VFAT Their core is based on the FAT filesys tem MSDOS is a traditional DOS file system with 14 character filename CONTENTS 133 contraint and is the most simple variant of FAT filesystem UMSDOS which was not widely used and likely won t be is a method of storing long filenames without making any change to the FAT structure itself It s running on FAT also VFAT is the latest filesystem used by Windows 95 98 to store long filenames Linux supports FAT32 next FAT implic itly This filesystem does not have automatic defragmentation and wastes some space in management but has high recovery ratio even recovers deleted files Gotta loose FAT ISO9660 cd rom filesystem Linux ca
160. ories with long names All that is necessary are the first unique char acters of the filename followed by a lt Tab gt and the sytem will complete If you haven t entered enough characters hitting lt Tab gt lt Tab gt will provide all possible matches Commands can also be completed with lt Tab gt If you hit lt Tab gt lt Tab gt with no arguments you will get something like this lt Tab gt lt Tab gt There are 1661 possibilities Do you really wish to see them all y or n However if you enter just the first couple of letters like this log lt Tab gt lt Tab gt logger logname logresolve logtail login logout logrotate Then you get all the possible commands with the first three letters log Filename Expansion You can use wildcard characters to expand commands to speed up access Suppose you knew their was a configuration file that you needed to modify because you recently added some new libraries You know the configuration file is in etc and you know it begins with an 1 but you can t remember the name You could use the filename expansion capabilities of the shell to find Id so conf cd etc ls d 1 ld so cache localtime logrotate conf lynx cfg ld so conf localtime rpmnew logrotate d lilo conf login defs ltrace conf The means substitute any or no string following the 1 The d argument says don t traverse directories So the command returns all files and directories in the current di
161. ormation is lost that way and in particular working with the loop device will be less convenient OPTIONS The full set of options used by an invocation of mount is determined by first extracting the options for the file system from the fstab table then applying any options specified by the o argument and finally applying a r or w option when present Options available for the mount command V Output version h Print a help message v Verbose mode a Mount all filesystems of the given types mentioned in fstab F Used in conjunction with a Fork off a new incarnation of mount for each device This will do the mounts on different devices or different NFS servers in parallel This has the advantage that it is faster also NFS timeouts go in parallel A disadvantage is that the mounts are done in undefined order Thus you cannot use this option if you want to mount both usr and usr spool f Causes everything to be done except for the actual system call if it s not obvious this fakes mounting the file system This option is useful in conjunction with the v flag to determine what the mount command is trying to do It can also be used to add entries for devices that were mounted ear lier with the n option CONTENTS 58 n Mount without writing in etc mtab This is necessary for example when etc is on a read only file system s Tolerate sloppy mount options rather than failing This will ignore mount o
162. ostic information no387 causes Linux to ignore the math coprocessor even if you have one no hlt run an infinite loop when there is nothing else to do and to not halt your CPU when there is no activity no scroll disables scrolling features that make it difficult to use Braille termi nals noapic do not use some of the advanced features of the interrupt controller on multi processor machines noht disable hyper threading on intel processors that have this feature noisapnp if ISA PnP is built into the kernel this will disable it nomce disable the ability in some newer processors to self monitor and detect inconsistencies and create Machine Check Exception and halt the system nosmp If software suspend is enabled and a suspend to disk file has been specified using this argument will give a normal boot and the suspend data will be ignored notsc tell the kernel to not use the Time Stamp Counter for anything even if the CPU has one nofxsr tell the kernel to not use any speed up tricks involving the floating point unit even if the processor supports them CONTENTS 120 panic automatically reset after a kernel panic so that the machine comes back on line pci argument not avail in v2 0 kernels can be used to change the behaviour of PCI bus device probing and device behaviour pirq tells a SMP kernel information on the PCI slot versus IRQ settings for SMP motherboards which are unknown or known to be blacklisted profile kern
163. ot changed If the user name is followed by a colon or dot and a group name or numeric group ID with no spaces between them the group ownership of the files is changed as well If a colon or dot but no group name follows the user name that user is made the owner of the files and the group of the files is changed to that user s login group If the colon or dot and group are given but the user name is omitted only the group of the files is changed in this case chown performs the same function as chgrp OPTIONS c changes Verbosely describe only files whose ownership actually changes f silent quiet Do not print error messages about files whose ownership can not be changed v verbose Verbosely describe ownership changes R recursive Recursively change ownership of directories and their contents help Print a usage message on standard output and exit successfully version Print version information on standard output then exit successfully EXAMPLES Is l rw rw rw 1 root root 0 Mar 26 19 22 firstfile rw rw rw 1 root root 0 Mar 26 19 22 fourfile rw rw rw 1 root root 0 Mar 26 19 22 lastfile rw rw rw 1 root root 0 Mar 26 19 22 onefile rw rw rw 1 root root 0 Mar 26 19 22 thatfile rw rw rw 1 root root 29 Mar 26 19 23 thisfile rw rw rw 1 root root 0 Mar 26 19 22 thosefiles rw rw rw 1 root root 0 Mar 26 19 22 threefile rw rw rw 1 root root 0 Mar 26 19 22 twofile CONTENTS 15 cp NAME c
164. ot consider an argument direc tory that already exists to be an error help Print a usage message on standard output and exit successfully version Print version information on standard output then exit successfully EXAMPLES ls mkdir bin ls bin cat NAME cat concatenate files and print on the standard output SYNOPSIS cat benstuvAET number number nonblank squeeze blank show nonprinting show ends show tabs show all help version file CONTENTS 10 DESCRIPTION This documentation is no longer being maintained and may be inaccurate or incomplete The Texinfo documentation is now the authoritative source This manual page documents the GNU version of cat cat writes the contents of each given file or the standard input if none are given or when a file named is given to the standard output OPTIONS b number nonblank Number all non blank output lines starting with 1 e Equivalent to vE n number Number all output lines starting with 1 s squeeze blank Replace multiple adjacent blank lines with a single blank line t Equivalent to vT u Ignored for Unix compatibility v show nonprinting Display control characters except for LFD and TAB us ing notation and precede characters that have the high bit set with M A show all Equivalent to vET E show ends Display a after the end of each line T show tabs Display TAB
165. ou can easily select which OS it boots To allow you to customize the menu GRUB will load a preexisting configuration file Note that you can not only enter the command line interface whenever you like but also you can edit specific menu entries prior to using them Naming conventions The device syntax used in GRUB is a wee bit different from what you may have seen before in your operating system s and you need to know it so that you can specify a drive partition hd0 1 Here hd means it is a hard disk drive The first integer 0 indicates the drive number that is the first hard disk while the second integer 1 indicates the partition number or the PC slice number in the BSD terminology Once again please note that the partition numbers are counted from _zero_ not from one This expression means the second partition of the first hard disk drive In this case GRUB uses one partition of the disk instead of the whole disk Of course to actually access the disks or partitions with GRUB you need to use the device specification in a command like root fd0 or unhide hd0 2 To help you find out which number is a partition you want the GRUB command line options have argument completion That means that for example you only CONTENTS 110 need to type root followed by a lt TAB gt and GRUB will display the list of drives partitions or file names so it should be quite easy to determin
166. ou wanted to limit the amount of memory available to linux memfrac memory is broken down into zones the two or three integers supplied here determine how much memory in each zone should be kept free swap tune some of the virtual memory VM parameters that are related to swapping to disk buff allows the user to tune some of the parameters related to buffer memory management acpi currently this only accepts off to disable the ACPI subsystem console to be able to use another device like a serial port or even a printer to be the console when no video device is present debug the kernel communicates important and not so important messages to the operator via the printk function decnet supply two comma separated integers here to give your area and node respectively devfs if you are using devfs instead of the standard static devices in dev then you can supply the words only or mount with this argument gpt if you are using EFI GUID Partition Table handling you can use this to override problems associated with an invalid PMBR idle setting this to poll causes the idle loop in the kernel to poll on the need reschedule flag instead of waiting for an interrupt to happen init if for example your init program got corrupted and thus stopped you from being able to boot you could simply use the boot prompt init bin sh which would drop you directly into a shell at boot allowing you to replace the corrupted pr
167. ous search was modified by E the search continues in the next or previous file if not satisfied in the current file If the previous search was modified by R the search is done without using regular expressions There is no effect if the previous search was modified by F or K CONTENTS 26 N Repeat previous search but in the reverse direction ESC n Repeat previous search but crossing file boundaries The effect is as if the previous search were modified by ESC N Repeat previous search but in the reverse direction and crossing file boundaries ESC u Undo search highlighting Turn off highlighting of strings matching the current search pattern If highlighting is already off because of a previous ESC u command turn highlighting back on Any search command will also turn highlighting back on Highlighting can also be disabled by tog gling the G option in that case search commands do not turn highlighting back on e filename Examine a new file If the filename is missing the current file see the n and p commands below from the list of files in the command line is re examined A percent sign in the filename is replaced by the name of the current file A pound sign is replaced by the name of the previously examined file However two consecutive percent signs are simply replaced with a single percent sign This allows you to enter a filename that contains a percent sign in the name Similarly two con se
168. p copy files SYNOPSIS cp options source dest cp options source directory Options abdfilprsuvxPR S backup suffix V numbered existing sim ple backup no dereference force interactive one file system preserve recursive update ver bose suffix backup suffix version control numbered exist ing simple archive parents ink symbolic link help version DESCRIPTION This documentation is no longer being maintained and may be inaccurate or incomplete The Texinfo documentation is now the authoritative source This manual page documents the GNU version of cp If the last argument names an existing directory cp copies each other given file into a file with the same name in that directory Otherwise if only two files are given it copies the first onto the second It is an error if the last argument is not a directory and more than two files are given By default it does not copy directories OPTIONS a archive Preserve as much as possible of the structure and attributes of the original files in the copy The same as dpR b backup Make backups of files that are about to be overwritten or removed d no dereference Copy symbolic links as symbolic links rather than copying the files that they point to and preserve hard link relationships between source files in the copies f force Remove existing destination files i interactive Prompt whether to overwrite existin
169. parated list of databases to search SEE ALSO find 1L locatedb 5L updatedb 1L xargs 1L Finding Files on line in Info or printed Is NAME ls dir vdir list contents of directories SYNOPSIS ls abcdfgiklmnpqrstuxABCFGLNQRSUX 1 w cols T cols I pattern all escape directory inode kilobytes numeric uid gid no group hide control chars reverse size width cols tab size cols almost all ignore backups classify file type full time ignore pattern derefer ence literal quote name recursive sort none time size extension format long verbose commas across vertical single column time atime access use ctime status help ver sion color yes no tty colour yes no tty name DESCRIPTION This documentation is no longer being maintained and may be inaccurate or incomplete The Texinfo documentation is now the authoritative source This manual page documents the GNU version of Is dir and vdir are versions of ls with different default output formats These programs list each given file or directory name Directory contents are sorted alphabetically For ls files are by default listed in columns sorted vertically if the standard output is a terminal otherwise they are listed one per line For dir files are by default listed in columns sorted vertically For vdir files are by default listed in long format CONTENTS 45
170. ptions not supported by a filesystem type Not all filesystems support this option This option exists for support of the Linux autofs based au tomounter r Mount the file system read only A synonym is o ro w Mount the file system read write This is the default A synonym is o rw t vfstype The argument following the t is used to indicate the file system type The file system types which are currently supported are listed in linux fs filesystems c minix ext ext2 xiafs hpfs msdos umsdos vfat proc nfs iso9660 smbfs ncpfs affs ufs romfs sysv xenix coher ent Note that the last three are equivalent and that xenix and coherent will be removed at some point in the future use sysv instead Since kernel version 2 1 21 the types ext and xiafs do not exist anymore The type iso9660 is the default If no t option is given or if the auto type is specified the superblock is probed for the filesystem type minix ext ext2 xiafs iso9660 romfs are supported If this probe fails and proc filesystems exists then all of the filesystems listed there will be tried except for those that are labeled nodev e g proc and nfs Note that the auto type may be useful for user mounted floppies Warning the probing uses a heuristic the presence of appropriate magic and could recognize the wrong filesystem type More than one type may be specified in a comma separated list The list of file system types can be pre
171. pts are generally easy to read and figure out Most of them exam ine their command line input and do the appropriate thing corresponding to arguments of start stop restart status Sometimes there is a reload argument which may be either a synonym for restart or perhaps a more effi cient re initialization So now you know a configuration trick if you change CONTENTS 128 some configuration data file associated with say sendmail you can ensure the changes are honored by executing the command etc re d init d sendmail restart don t forget the argument restart Be aware that script names often duplicate the name of a binary executable somewhere in your path so DON T try to execute for example sendmail restart this will not work Managing runlevels tools and references Different Linux distributions use runlevels differently One commonality is that runlevels 0 and 6 are reserved for shutdown and runlevel 1 is single user mode Single user mode is generally used for doing system repairs On Red Hat sys tems runlevel 2 is mult user without networking runlevel 3 is multi user with networking runlevel 4 is for custom configuration and runlevel 5 is multi user with graphical login There are a at least three tools for configuring and managing runlevels on Red Hat Linux systems The graphical interface tool redhat config services can be reached from Menu gt System Settings gt S
172. r 1 so you could use root 0x801 as an alternative Other paramers Other parameters that can be passed to the kernel include rootflags allows you to give options pertaining to the mounting of the root filesystem rootfstype allows you to give a comma separated list of fs types that will be tried for a match when trying to mount the root filesystem ro tells the kernel to mount the root filesystem as readonly rw tells the kernel to mount the root filesystem as read write nfsroot tells the kernel which machine what directory and what NFS options to use for the root filesystem root dev nfs is required ip or nfsaddrs sets up the various network interface addresses that are required to communicate over the network ramdisk_start allow a kernel image to reside on a floppy disk along with a compressed ramdisk image load_ramdisk tells the kernel whether it is to try to load a ramdisk image or not prompt_ramdisk tells the kernel whether or not to give you a prompt asking you to insert the floppy containing the ramdisk image ramdisk_size override the default of 4096 4MB to a bigger or smaller size with this boot argument ramdisk_blocksize tuned for better memory management behaviour noinitrd determines what happens to the initrd data after the kernel has booted CONTENTS 118 cachesize override level 2 CPU cache size detection in kB mem to specify the amount of installed memory or a value less than that if y
173. r pipes so that only the number of buffers specified by the b option are used Warning use of B can result in erroneous display since only the most recently viewed part of the file is kept in memory any earlier data is lost CONTENTS 29 c Causes full screen repaints to be painted from the top line down By default full screen repaints are done by scrolling from the bottom of the screen C The C option is like c but the screen is cleared before it is repainted d The d option suppresses the error message normally displayed if the terminal is dumb that is lacks some important capability such as the ability to clear the screen or scroll backward The d option does not otherwise change the behavior of less on a dumb terminal e Causes less to automatically exit the second time it reaches end of file By default the only way to exit less is via the q command E Causes less to automatically exit the first time it reaches end of file f Forces non regular files to be opened A non regular file is a directory or a device special file Also suppresses the warning message when a binary file is opened By default less will refuse to open non regular files g Normally less will highlight ALL strings which match the last search com mand The g option changes this behavior to highlight only the particular string which was found by the last search command This can cause less to run somewhat faster than the default
174. rbid an ordinary i e non root user to mount the file system This is the default remount Attempt to remount an already mounted file system This is commonly used to change the mount flags for a file system especially to make a readonly file system writeable ro Mount the file system read only rw Mount the file system read write suid Allow set user identifier or set group identifier bits to take effect sync All I O to the file system should be done synchronously user Allow an ordinary user to mount the file system This option implies the options noexec nosuid and nodev unless overridden by subsequent options as in the option line user exec dev suid FILESYSTEM SPECIFIC MOUNT OPTIONS The following options apply only to certain file systems We sort them by file system They all follow the o flag CONTENTS 60 Mount options for affs uid value and gid value Set the owner and group of the root of the file system default uid gid 0 but with option uid or gid without specified value the uid and gid of the current process are taken setuid value and setgid value Set the owner and group of all files mode value Set the mode of all files to value amp 0777 disregarding the original permissions Add search permission to directories that have read permis sion The value is given in octal protect Do not allow any changes to the protection bits on the file system usemp Set uid and gid of the root of the file system
175. rbose the size totals and compression ratio for all files is also displayed unless some sizes are unknown With quiet the title and totals lines are not displayed L license Display the gzip license and quit n no name When compressing do not save the original file name and time stamp by default The original name is always saved if the name had to be truncated When decompressing do not restore the original file name if present remove only the gzip suffix from the compressed file name and do not restore the original time stamp if present copy it from the compressed file This option is the default when decompressing N name When compressing always save the original file name and time stamp this is the default When decompressing restore the original file name and time stamp if present This option is useful on systems which have a limit on file name length or when the time stamp has been lost after a file transfer q quiet Suppress all warnings r recursive Travel the directory structure recursively If any of the file names specified on the command line are directories gzip will descend into the directory and compress all the files it finds there or decompress them in the case of gunzip S suf suffix suf Use suffix suf instead of gz Any suffix can be given but suffixes other than z and gz should be avoided to avoid confusion when files are trans ferred to other systems A null suffix forces gu
176. re are some other resources about RPM if you would like to learn more RPM Web Site http www rpm org RPM FTP Site ftp ftp rpm org pub Maximum RPM a book by Ed Bailey It s available in hardback and is 442 pages long and includes a quick reference card The book covers everything from general RPM usage to building your own RPMs to programming with rpmlib There is a link on the RPM Web Site where you can download the compressed file of the book in PostScript or KIEX Red Hat Web Site http www redhat com System Configuration Webmin redhat config Lan Barnes 151 Upgrading Software and the Kernel Archive and Compression Utilities These are utilities for archiving Utilities like gzip can be used with archiving utilities like tar to compress the file before archiving This allows more data to be stored on the archive media gzip gunzip zcat gzip gunzip zcat compress or expand files Gzip reduces the size of the named files using Lempel Ziv coding LZ77 Whenever possible each file is replaced by one with the extension gz while keeping the same own ership modes access and modification times If no files are specified or if a file name is the standard input is compressed to the standard output Gzip will only attempt to compress regular files In particular it will ignore symbolic links By default gzip keeps the original file name and timestamp in the compressed file These are used when decompr
177. rectory that begin with the letter 1 If we knew the file began with ld we might form the command ls d ld ld so cache ld so conf CONTENTS 88 The substitutes for any single character It is more usefull for seperating similar filenames with single character differences If we wanted to see a listing of all the files under usr man we could do the following cd usr man ls manl man3 man5 man7 man9 mann man2 man4 man6 man8 manl whatis Is man lt returned_long_list gt Redirection Redirection allows you to take the ouput from a command and redirect it to a file This allows you to capture If we wanted to capture the output of the ls man command we could redirect it to a file Is man gt manfiles list ls manl man4 man7 manfiles list whatis man2 man5 man8 manl man3 man6 man9 mann If the file manfiles list doesn t exist it will be created If there is a file man files list it will be overwritten It is also possible to redirect the input We could mail the file we just created by redirecting the standard input of the mail command like this mail lt manfiles list Suppose we want to append a list from another man directory usr local man to this list We would use the append gt gt redirection to add them to the manfiles list like this cd usr local man ls man gt gt usr man manfiles list CONTENTS 89 Connecting with Pipes It is possi
178. rgument to this CONTENTS 69 option are like the GNU Emacs version control variable they also rec ognize synonyms that are more descriptive The valid values are unique abbreviations are accepted rw or numbered Always make numbered backups nil or existing Make numbered backups of files that already have them sim ple backups of the others never or simple Always make simple backups EXAMPLES Rename thisfile to thatfile mv thisfile thatfile Move a file from one directory to another You only have to give the path to the new place the file name will be the same unless you choose to change it mv thisfile home joe ps NAME ps report process status SYNOPSIS ps lujsvmaxScewhrnu txx O k1 k2 pids there are also three long options sortX key keyl help version More long options are on the way CONTENTS 70 DESCRIPTION ps gives a snapshot of the current processes If you want a repetitive update of this status use top This man page documents the proc based version of ps or tries to COMMAND LINE OPTIONS The command line options for this version of ps are derived from the BSD version of ps not the System V version The command line arguments should not be preceded by a character because in the future a will be used to indicate Unix98 standard command line arguments while no will i
179. roups for working on things in a cooperative way such as groups of programmers working on a single project To examine the attributes of files use ls l like this joe localhost Is 1 drwxr xr x 2 joe joe 1024 Mar 27 18 17 bin rw rw rw 1 joe joe 0 Mar 26 19 22 firstfile rw rw rw 1 joe joe 0 Mar 26 19 22 fourfile rw rw rw 1 joe joe 0 Mar 26 19 22 lastfile rw rw rw 1 joe joe 0 Mar 26 19 22 onefile rw rw rw 1 joe joe 29 Mar 27 01 37 thatfile rw rw rw 1 joe joe 29 Mar 26 19 23 thisfile rw rw rw 1 joe joe 0 Mar 26 19 22 thosefiles rw rw rw 1 joe joe 0 Mar 26 19 22 threefile rw rw rw 1 joe joe 0 Mar 26 19 22 twofile CONTENTS 95 Working from right to left you can see the attributes of the files First on the right is the name of the file or directory Second from right is the date and time of creation Third is the file size The fourth column is the group and fifth is owner for the file Then we come to the first column which is the file attributes Each file has three levels of permissions or modes owner group and user Owner The owner is the the user who created the file The chown command is used to change this Group Files can be grouped together for access under etc group for projects where group access is neccessary For security the default setup in Red Hat is to create a group for each user User Sometimes refered to as Public All other users on the system Anyone who has a username and can gain access to t
180. run on a variety of terminals There is even limited support for hardcopy terminals On a hardcopy terminal lines which should be printed at the top of the screen are prefixed with a caret Commands are based on both more and vi Commands may be preceded by a decimal number called N in the descriptions below The number is used by some commands as indicated CONTENTS 23 COMMANDS In the following descriptions X means control X ESC stands for the ESCAPE key for example ESC v means the two character sequence ESCAPE then v h or H Help display a summary of these commands If you forget all the other commands remember this one SPACE or V or for F Scroll forward N lines default one window see option z below If N is more than the screen size only the final screenful is displayed Warning some systems use V as a special literalization character z Like SPACE but if N is specified it becomes the new window size ESC SPACE Like SPACE but scrolls a full screenful even if it reaches end of file in the process RETURN or N or ec or E or j or J Scroll forward N lines default 1 The entire N lines are displayed even if N is more than the screen size dor D Scroll forward N lines default one half of the screen size If N is specified it becomes the new default for subsequent d and u commands b or B or ESC v Scroll backward N lines default one window see option z below If N is more than the screen size
181. s For example G tells less to start at the end of the file rather than the beginning and xyz tells it to start at the first occurrence of xyz in the file As a special case lt number gt acts like lt number gt g that is it starts the display at the specified line number however see the caveat under the g command above If the option starts with the initial command applies to every file being viewed not just the first one The command described previously may also be used to set or change an initial command for every file CONTENTS 33 LINE EDITING When entering command line at the bottom of the screen for example a file name for the e command or the pattern for a search command certain keys can be used to manipulate the command line Most commands have an alternate form in brackets which can be used if a key does not exist on a particular keyboard The bracketed forms do not work in the MS DOS version Any of these special keys may be entered literally by preceding it with the literal character either V or A A backslash itself may also be entered literally by entering two backslashes LEFTARROW ESC h Move the cursor one space to the left RIGHTARROW ESC 1 Move the cursor one space to the right LEFTARROW ESC b or ESC LEFTARROW That is CONTROL and LEF TARROW simultaneously Move the cursor one word to the left RIGHTARROW ESC w ESC RIGHTARROW That is CONT
182. s a warning message but continues Unless the BIOS really supports more than two drives the system will not be able to boot in that case There are four approaches of how such problems can be solved use of a different partition which is on an accessible disk and which does not exceed the 1024 cylinder limit If there is only a DOS partition which fulfills all the criteria that partition can be used to store the relevant files rearranging partitions and disks This is typically a destructive operation so extra care should be taken to make good backups if the system is running DOS or Windows 95 LOADLIN can be used instead of LILO if all else fails installation of a more capable BIOS a different controller or a different disk configuration LILO depends on the BIOS to load the following items e boot boot b e boot map created when running sbin lilo e all kernels e the boot sectors of all other operating systems it boots e the startup message if one has been defined Typically what most Linux distributions do is create a small boot partition at the beginning of the drive from 50 100Mb This insures that the required files will be within the 1024 cylinder boundary Other strategies include using Logical Block Addressing LBA which fools the bios into seeing the disc geometry with 1024 cylinders or less CONTENTS 107 The boot prompt Immediately after it s loaded LILO checks whether one of the following i
183. s constructed by smbmount 8 and the current version of mount 2 6c does not know anything about smb Mount options for sysv None Mount options for ufs None Mount options for umsdos See mount options for msdos The dotsOK option is explicitly killed by umsdos Mount options for vfat First of all the mount options for fat are recognized The dotsOK option is explicitly killed by vfat Further more there are uni_xlate Translate unhandled Unicode characters to special escaped sequences This lets you backup and restore filenames that are created with any Unicode characters Without this option a is used when no translation is possible The escape character is because it is otherwise illegal on the vfat filesystem The escape sequence that gets used where u is the unicode character is u amp 0x3f u gt gt 6 amp 0x3f u gt gt 12 posix Allow two files with names that only differ in case nonumtail First try to make a short name without sequence number before trying name num ext CONTENTS 67 Mount options for xenix None Mount options for xiafs None Although nothing is wrong with xiafs it is not used much and is not maintained Probably one shouldn t use it Since Linux version 2 1 21 xiafs is no longer part of the kernel source THE LOOP DEVICE One further possible type is a mount via the loop device For example the command mount tmp fdimage mnt t m
184. s hap pening e any of the Shift Control or Alt keys is pressed e CapsLock or ScrollLock is set If this is the case LILO displays the boot prompt and waits for the name of a boot image i e Linux kernel or other operating system Otherwise it boots the default boot image or if a delay has been specified waits for one of the listed activities until that amount of time has passed At the boot prompt the name of the image to boot can be entered Typing errors can be corrected with BackSpace Delete Ctrl U and Ctrl X A list of known images can be obtained by pressing or Tab If Enter is pressed and no file name has been entered the default image is booted Boot command line options LILO is also able to pass command line options to the kernel Command line options are words that follow the name of the boot image and that are separated by spaces boot linux single root 200 Recent kernels recognize a large number of options among them are debug n0387 no hlt ramdisk size reserve base size root device ro and rw All current init programs also recognize the option single The options lock and vga are processed by the boot loader itself Boot command line options are always case sensitive There is also a plethora of options to specify certain characteristics e g IO and memory addresses of devices Some common ones are ether floppy hd bmouse and sound The usage of these option
185. s horizontally with as many as will fit on each line separated by commas n numeric uid gid List the numeric UID and GID instead of the names p Append a character to each file name indicating the file type q hide control chars Print question marks instead of non graphic characters in file names r reverse Sort directory contents in reverse order s size Print the size of each file in 1K blocks to the left of the file name If the environment variable POSIXLY_CORRECT is set 512 byte blocks are used instead t sort time Sort directory contents by timestamp instead of alphabetically with the newest files listed first CONTENTS 46 u time atime time access time use Sort directory contents according to the files last access time instead of the modification time If the long listing format is being used print the last access time instead of the mod ification time x format across format horizontal List the files in columns sorted hori zontally A almost all List all files in directories except for and B ignore backups Do not list files that end with unless they are given on the command line C format vertical List files in columns sorted vertically F classify Append a character to each file name indicating the file type For regular files that are executable append a The file type indicators are for directories for
186. s is option number Please consult the corresponding FAQs and HOWTOs for details Options of the type variable value which are neither standard options nor device specific options cause the respective variables to be set in the environ ment passed to init The case of the variable name is preserved i e it isn t automatically converted to upper case See the section on init below for further clues about these options CONTENTS 108 GRUB Introduction This information is summarized from the GNU GRUB web site http www gnu org software grub docu1 and from the grub info pages info grub Many Linux distributions give you the option of using GRUB as you bootloader during the install You don t need all this information to use grub However if you need to dual boot to a proprietary OS or need to recover from a damaged Master Boot Record you may find this information valuable GNU GRUB is a Multiboot boot loader It was derived from GRUB GRand Unified Bootloader which was originally designed and implemented by Erich Stefan Boleyn Briefly boot loader is the first software program that runs when a computer starts It is responsible for loading and transferring control to the operating system kernel software such as the Hurd or the Linux The kernel in turn initializes the rest of the operating system e g GNU GNU GRUB follows these requirements below e Compliant with the Multiboot Specification e Basic fu
187. s the primary binary directory bin is designated as a directory on the system where binary executable files are Nearly all the commands shown below are contained in the bin directory Also you will find other similar binary directories for a similar purpose in usr bin and usr local bin Generally the deeper in the directory tree you go the more unique the system becomes Often users will have their own bin directory where they keep custom scripts and binaries for their personal use CONTENTS 5 boot is where the kernel related files and files necessary to boot the system are kept If you compile a new kernel you will place the kernel in this directory dev the device directory This points to one of the features of Linux To the system everything is a file So nearly every hardware device in you system will have a file in this directory associated with it Some of these include fd0 for the first floppy hda and sda for the first ide and scsi hard drives etc is where most all system wide configuration files are Files to configure nameservices web servers Login filesystem ftp server name server newserver filesystem X configuration files are all kept in etc as well as most of the system initialization files If your looking for a file to configure a service on your system the first place to look is etc There are other etc directories on some systems usr etc usr local etc and usr X11R6 lib X11 etc which are directories
188. same as requires provides List capabilities this package provides changelog Display change information for the package l List files in package s Display the states of files in the package implies 1 The state of each file is either normal not installed or replaced d List only documentation files implies l c List only configuration files implies l scripts List the package specific shell scripts that are used as part of the installation and uninstallation processes if there are any triggers Display the trigger scripts if any which are contained in the package dump Dump file information as follows path size mtime md5sum mode owner group isconfig isdoc rdev sym link This must be used with at least one of l c d CONTENTS 149 Verifying with RPM Verifying a package compares information about the installed files in the package with information about the files taken from the original package and stored in the rpm database Among other things verifying compares the size MD5 sum permissions type owner and group of each file Any discrepencies are displayed The package specification options are the same as for package querying Verifying rpms is used as a method of determing changes that may have been made to a system after a security breach The form this takes is root localhost rpm Va This will report all changes to files since the original installation of packages It requires some
189. scrolling window size to n lines The default is one screenful The z and w commands can also be used to change the window size The z may be omitted for compatibility with more If the number n is negative it indicates n lines less than the current screen size For example if the screen is 24 lines z 4 sets the scrolling window to 20 lines If the screen is resized to 40 lines the scrolling window automatically changes to 36 lines Changes the filename quoting character This may be necessary if you are trying to name a file which contains both spaces and quote characters Followed by a single character this changes the quote character to that character Filenames containing a space should then be surrounded by that character rather than by double quotes Followed by two characters changes the open quote to the first character and the close quote to the second character Filenames containing a space should then be preceded by the open quote character and followed by the close quote character Note that even after the quote characters are changed this option remains a dash followed by a double quote A command line argument of marks the end of option arguments Any arguments following this are interpreted as filenames This can be useful when viewing a file whose name begins with a or If a command line option begins with the remainder of that option is taken to be an initial command to les
190. sdos o loop dev loop3 blocksize 1024 will set up the loop device dev loop3 to correspond to the file tmp fdimage and then mount this device on mnt This type of mount knows about three options namely loop offset and encryption that are really options to losetup 8 If no explicit loop device is mentioned but just an option o loop is given then mount will try to find some unused loop device and use that EXAMPLES Mount a DOS floppy disk to mnt floppy mount t msdos dev fd0 mnt floppy Mount a cd to mnt cdrom mount t iso9660 dev cdrom mnt cdrom mv NAME mv rename files CONTENTS 68 SYNOPSIS mv options source dest mv options source directory Options bfiuv S backup suffix V numbered existing sim ple backup force interactive update verbose suffix backup suflix version con trol numbered existing simple help version DESCRIPTION This documentation is no longer being maintained and may be inaccurate or incomplete The Texinfo documentation is now the authoritative source This manual page documents the GNU version of mv If the last argument names an existing directory mv moves each other given file into a file with the same name in that directory Otherwise if only two files are given it moves the first onto the second It is an error if the last argument is not a directory and more than two files are given It can move only regular files across filesyste
191. sed to drive the cron daemon Each user can have their own crontab and though these are files in var they are not intended to be edited directly What does a crontab file look like The users crontab file looks like this man 5 crontab Ill gt Day of week 0 or 7 Sunday 1 Monday Command gt Month 0 12 160 CONTENTS 161 gt Day of month 0 31 gt Hour of day 0 23 ee gt Minute of hour 0 59 The system cron tab looks like the above with an additional entries user command The typical Redhat crontab file looks like this The times may be different SHELL bin bash PATH sbin bin usr sbin usr bin MAILTO root run parts 01 root run parts etc cron hourly 02 4 root run parts etc cron daily 22 4 4 root run parts etc cron weekly 12 4 1 root run parts etc cron monthly The MAILTO environment variable is used to specify where the output for that particular job should be sent to if not set it gets mailed to the owner of the crontab file The program run parts is explained in another section but what it does is exe cute every file with the x execute bit set on programs listed in the directory as the option So every file in the etc cron hourly will be executed 1 minute after each hour Every file in the etc cron daily will be executed at 4 02 AM You may notice that there is a user logging in at this time calle
192. sources etc re d init d functions rcN d N 0 1 6 the elegance revealed All files in any rcN d subdirectory are symbolic links and with one excep tion they all link to scripts in ete rc d init d for example S40crond links to ete rc d init d crond The exception is the start script S99local in runlevels 2 5 only which is a link to etc re d rc local The default rc local script BTW doesn t do very much of great complexity it only creates the file var lock subsys local on startup It s only other re maining purpose is as a location for custom initializations for which the system administrator doesn t wish to create a complete startup script in etc init d and that is desired in all normal runlevels update from ud once sbin update after the runlevel specific configuration step above the any runlevel line from inittab gets run gettys sbin mingetty ttyl and similar respawn action lines the getty programs are started after everything else That s it After the terminal gettys are started you can login on any virtual console or accept connections if any gettys were created on serial ports More about etc rc d init d scripts Typically the scripts in etc init d follow a standard format and commonly ei ther start or killa daemon But they could do anything The nfsfs script for example mounts or unmounts all nfs filesystems that are defined in etc fstab These scri
193. state can take a very long time delaying the availability of the server Journaling filesystems use a principal called Atomicity to maintain a consistency What this means is that all operations belonging to a transaction look as if they are atomic operations that can t be partially performed After every transaction there must be a commit operation making sure the buffers be written to disk All operations are completed wihout errors or canceled All metadata is logged in a journaling file system Metadata are the control structures inside a file system i nodes free block allocation maps i nodes maps etc After a system crash the log can be checked back to the first commit statement writing the arguments content back to its position on the disk Filesystem Types These are a few popular filesystems used in Linux Ext2fs Second Extended filesystem Linux calls this ext2 This is de facto filesystem for Linux created by Remy Card Wayne Davidson and others Ext2fs provides good performance especially when reading large files long filenames a set of management tools UNIX type security low fragmentation and read ahead to name a few Ext2fs maximum size is 8GB and can have maxinum filesize of Xgb Ext2fs is still under development it doesn t mean that it is unstable but means that there are things that can be improved or implemented and it s planned to include easy restoration of deleted file Access Control List f
194. status function to check whether a program is running or not echo_success function for reporting the successful start of a program during bootup echo_failure function for reporting the failure of the starting of a program echo_passed function to report the passing of a system test echo_warning function to report a warning success function logs that something succeeded calls echo_success failure function logs the failure of some process calls echo_failure passed function logs that something passed possibly with errors calls echo_passed warning function logs a warning calls echo_warning action run some action and log its output confirm function used during interactive startup to verify that you want service to start Other scripts Other scripts that get called from etc rc d if they exist etc rc d re serial may be needed to setup non standard serial ports etc re d rc modules comments say for backward compatibility with VARs if you ever find yourself tempted to edit this file consider putting your additions in another script etc rc local CONTENTS 127 TC etc re d re 3 etc re d re is the script and 3 is a command line argument telling it to process the runlevel 3 subdirectory etc rc d rc3 d It s respon sible for starting and stopping services when the runlevel changes Runs all kill scripts and then all start scripts Before running anything it reads
195. stent fat 12 fat 16 Specify either a 12 bit fat or a 16 bit fat This overrides the automatic FAT type detection routine Use with caution quiet Turn on the quiet flag Attempts to chown or chmod files do not return errors although they fail Use with caution sys immutable showexec dots nodots dotsOK yes no Various misguided at tempts to force Unix or DOS conventions onto a FAT file system Mount options for hpfs uid value and gid value Set the owner and group of all files Default the uid and gid of the current process umask value Set the umask the bitmask of the permissions that are not present The default is the umask of the current process The value is given in octal case lower case asis Convert all files names to lower case or leave them Default case lower conv binary conv text conv auto For conv text delete some ran dom CRs in particular all followed by NL when reading a file For conv auto choose more or less at random between conv binary and conv text For conv binary just read what is in the file This is the default nocheck Do not abort mounting when certain consistency checks fail CONTENTS 64 Mount options for iso9660 Normal iso9660 filenames appear in a 8 3 format i e DOS like restrictions on filename length and in addition all characters are in upper case Also there is no field for file ownership protection number of links provision for block character devices
196. symbolic links for FIFOs for sockets and nothing for regular files G no group Inhibit display of group information in a long format directory listing L dereference List the files linked to by symbolic links instead of listing the contents of the links N literal Do not quote file names Q quote name Enclose file names in double quotes and quote non graphic characters as in C R recursive List the contents of all directories recursively S sort size Sort directory contents by file size instead of alphabetically with the largest files listed first U sort none Do not sort directory contents list them in whatever order they are stored on the disk This option is not called f because the Unix ls f option also enables a and disables I s and t It seems useless and ugly to group those unrelated things together in one option Since this option doesn t do that it has a different name X sort extension Sort directory contents alphabetically by file extension characters after the last files with no extension are sorted first 1 format single column List one file per line w width cols Assume the screen is cols columns wide The default is taken from the terminal driver if possible otherwise the environment variable COLUMNS is used if it is set otherwise the default is 80 CONTENTS 47 T tabsize cols Assume that each tabstop is cols columns wide The default
197. ters using the caret notation for example a control A octal 001 is displayed as A Warning when the r option is used less cannot keep track of the actual appearance of the screen since this depends on how the screen responds to each type of control character Thus various display problems may result such as long lines being split in the wrong place s Causes consecutive blank lines to be squeezed into a single blank line This is useful when viewing nroff output S Causes lines longer than the screen width to be chopped rather than folded That is the remainder of a long line is simply discarded The default is to fold long lines that is display the remainder on the next line ttag The t option followed immediately by a TAG will edit the file containing that tag For this to work there must be a file called tags in the current directory which was previously built by the ctags 1 command This option may also be specified from within less using the command as a way of examining a new file The command t is equivalent to specifying t from within less Ttagsfile Specifies a tags file to be used instead of tags u Causes backspaces and carriage returns to be treated as printable characters that is they are sent to the terminal when they appear in the input U Causes backspaces tabs and carriage returns to be treated as control char acters that is they are handled as specified by the r
198. the named file as a lesskey 1 file Multiple k options may be specified If the LESSKEY environment variable is set or if a lesskey file is found in a standard place see KEY BINDINGS it is also used as a lesskey file m Causes less to prompt verbosely like more with the percent into the file By default less prompts with a colon M Causes less to prompt even more verbosely than more n Suppresses line numbers The default to use line numbers may cause less to run more slowly in some cases especially with a very large input file Suppressing line numbers with the n option will avoid this problem Us ing line numbers means the line number will be displayed in the verbose prompt and in the command and the v command will pass the cur rent line number to the editor see also the discussion of LESSEDIT in PROMPTS below N Causes a line number to be displayed at the beginning of each line in the display ofilename Causes less to copy its input to the named file as it is being viewed This applies only when the input file is a pipe not an ordinary file If the file already exists less will ask for confirmation before overwriting it Ofilename The O option is like o but it will overwrite an existing file with out asking for confirmation If no log file has been specified the o and O options can be used from within less to specify a log file Without a file name they will simply report the name of the log file The
199. the three states of the file you are editing Pico may ask you a few questions before you exit the editor File not modified If the far right hand section of the status line at the top of the document does not display Modified hitting X will exit Pico without any prompting And you will be returned to the command prompt File modified and pre exists If you are editing a prevuouly existing file you started pico with the command pico lt file name gt and you have modified the file The far right hand section of the status line will display Modified Entering X will dispay the following text in the Command Input Line third from the bottom CONTENTS 176 Save modified buffer ANSWERING No WILL DESTROY CHANGES If you enter n the file will not be changed and you will exit to the command promt If you enter y the Command Input Line will change to File Name to write lt file name gt At this point you can hit the enter key to save the file as the file name you prevuoisly loaded or you can change it using the delte key and typng in a new file name You can also save it to another directoy by giving the path name commands like tmp mynewfile or mynewfile etc To exit either of these operations use the C command to abort and return to the Pico editor File modified and its a new file If you started Pico without giving a file name on the command prompt and you have edited the file whe
200. the user We ll cover environments later If you login incorrectly the system will not tell you that you typed in a wrong username or password It will only return login failed When you first boot a Linux system a banner is displayed identifying the system You may see something like the following information Red Hat Linux release 9 0 Shrike Kernel 2 4 20 on an i686 localhost login If you type in your username you get the following password If it is set up the Message Of The Day motd will be displayed You might also see a message from the system you have mail in var spool mail How to retrieve mail from the system is not a part of this tutorial so you ll have to read elsewhere for that information You type in your password correctly and you get the following CONTENTS 3 localhost This is the prompt If you entered you username or your password incorrectly you will be greeted by Login incorrect localhost login Don t panic try again Likely you either mis typed either your login name or your password Try again You re not logging in as root are you Adding users If you haven t already done so you should create a username on your system Once you are logged in as root you can do the following adduser joe passwd joe New UNIX password Retype new UNIX password passwd all authentication tokens updated successfully After this you can log off as root Ctr
201. timeo n retry n port n mountport n mounthost name mountprog n mountvers n nfsprog n nfsvers n namlen n The option addr n is accepted but ignored Also the following Boolean op tions possibly preceded by no are recognized bg fg soft hard intr posix cto ac tcp udp lock For details see nfs 5 Especially useful options include rsize 8192 wsize 8192 This will make your nfs connection much faster than with the default buffer size of 1024 hard The program accessing a file on a NFS mounted file system will hang when the server crashes The process cannot be interrupted or killed unless you also specify intr When the NFS server is back online the program will continue undisturbed from where it was This is probably what you want soft This option allows the kernel to time out if the nfs server is not responding for some time The time can be specified with timeo time This option might be useful if your nfs server sometimes doesn t respond or will be rebooted while some process tries to get a file from the server Usually it just causes lots of trouble nolock Do not use locking Do not start lockd CONTENTS 66 Mount options for proc uid value and gid value These options are recognized but have no effect as far as I can see Mount options for romfs None Mount options for smbfs Just like nfs the smb implementation expects a binary argument a struct smb_mount_data to the mount system call This argument i
202. tiple t options By default all filesystem types are listed X exclude type fstype Limit the listing to filesystems not of type fstype Multi ple filesystem types can be eliminated by giving multiple x options By default all filesystem types are listed v Ignored for compatibility with System V versions of df help Print a usage message on standard output and exit successfully version Print version information on standard output then exit successfully CONTENTS 19 EXAMPLES df Filesystem 1024 blocks Used Available Capacity Mounted on dev sdal 870677 694211 131486 84 dev sda5 2314835 1368909 826244 62 usr dev sda6 101075 27046 68810 28 var df i Filesystem Inodes Used IFree IUsed Mounted on dev sdal 225280 3334 221946 1 dev sda5 600064 60812 539252 10 usr dev sda6 26104 343 25761 1 var du NAME du summarize disk usage SYNOPSIS du abcklsxDLS all total count links summarize bytes kilobytes one file system separate dirs dereference dereference args help version file name DESCRIPTION This documentation is no longer being maintained and may be inaccurate or incomplete The Texinfo documentation is now the authoritative source This manual page documents the GNU version of du du displays the amount of disk space used by each argument and for each subdirectory of directory arguments The space is measured in 1K blocks by defa
203. to the uid and gid of the mount point upon the first sync or umount and then clear this option Strange verbose Print an informational message for each successful mount prefix string Prefix used before volume name when following a link volume string Prefix of length at most 30 used before when following a symbolic link reserved value Default 2 Number of unused blocks at the start of the device root value Give explicitly the location of the root block bs value Give blocksize Allowed values are 512 1024 2048 4096 grpquota noquota quota usrquota These options are accepted but ig nored Mount options for coherent None Mount options for ext None Note that the ext file system is obsolete Don t use it Since Linux version 2 1 21 extfs is no longer part of the kernel source CONTENTS 61 Mount options for ext2 The ext2 file system is the standard Linux file system Due to a kernel bug it may be mounted with random mount options fixed in Linux 2 0 4 bsddf minixdf Set the behavior for the statfs system call The minixdf be haviour is to return in the f_blocks field the total number of blocks of the file system while the bsddf behaviour which is the default is to subtract the overhead blocks used by the ext2 file system and not available for file storage Thus mount k o minixdf df k umount k Filesystem 1024 blocks Used Available Capacity Mounted on dev sda6
204. to verify the archive after writing it exclude FILE exclude file FILE X exclude from FILE exclude files listed in FILE Z compress uncompress filter the archive through compress Z gzip ungzip filter the archive through gzip use compress program PROG filter the archive through PROG which must accepted block compress block the output of compression program for tapes 0 7 Imh specify drive and density EXAMPLES To check a tar file contents tar tf foo tar If it s gzipped CONTENTS 86 tar tzf foo tar gz To extract the contents tar xzf foo tar gz To create a tar file of all the files in the etc directory tar cf etc tar etc To create a gzipped file of all the files and directories in usr local and see the files as they are placed in the archive tar czvf usr_local tgz usr local which NAME which show full path of commands SYNOPSIS which progname DESCRIPTION Which takes a series of program names and prints out the full pathname of the program that the shell would call to execute it It does this by simulating the shells searching of the PATH environment variable EXAMPLES Shortcuts Tab Completion One of the nicest things about Linux is the tab completion Tab completion allows you to type in the first few letters of a command or directory and then lt Tab gt to complete This can save quite a few keystrokes when entering deep CONTENTS 87 direct
205. turn to safety I heard stories of users who quit vi by rebooting their system Of course that doesn t help get your work done The rest of this primer will I hope give you a slightly bigger picture The sections below feature commands you will want to type Okay so what useful things can I do other than quit i Most users want to of course be able to add stuff to the file they re editing that being one of the main uses of an editor You can t just type straight away when you start vi you re in what may be called command mode where you enter commands Type the letter i for insert in lowercase This tells the 167 CONTENTS 168 editor that you want to insert text into your file more precisely the editing buffer since changes are not written back to the file unless explicitly told to see the section on dealing with files Just start typing from here on How do I get back into command mode lt Esc gt When you re in insert mode hitting the escape key will get you back into command mode Think of it as an escape from insert mode Help The arrow keys don t work No on some systems the arrow keys don t work If you re currently in insert mode get back into command mode see above then hit the keys corresponding to the direction you wish to move k to go up h to go left 1 to go right j to go down Remember to get back into insert mode before you start entering text a
206. uffer my favourite way of mak ing email signatures Gettin outta here wq ZZ Both of these do pretty much the same thing save changes made to the buffer and exit vi q Quits vi discarding all changes made to the editing buffer The Emacs Editor Dave Cook The Pico Editor What is Pico Pico is a basic console based text editor Pico is installed with the mail program Pine It can be installed without Pine I do believe look into it What Pico is not Pico is not a programmers editor It doesn t appear to be designed as a pro grammers editor it can still be used to edit program files when neccassary but for debuging purposes it lacks some abilites from other editors jumping by line number is not one of it s features Pico does a fine job of editing most of the text files used in the Unix Linux envirionment like the etc hosts file for instance Pico works and gets the job done CONTENTS 174 Starting Pico Pico is started with the command pico or pico lt file name gt where filename is the file to edit To edit your bashrc file you would type pico bashrc at the command prompt This poses a problem though when you want to edit a file that has a line length greater 80 characters Since Pico was designed to be used with Pine it defaults to use word wrap at 80 characters This doesn t work to well with some Linux configuration files To disable word wrapping when editing a file use the w opti
207. ult unless the environment variable POSIXLY_CORRECT is set in which case 512 byte blocks are used OPTIONS a all Display counts for all files not just directories b bytes Print sizes in bytes c total Write a grand total of all of the arguments after all arguments have been processed This can be used to find out the disk usage of a directory with some files excluded CONTENTS 20 k 1 S X D L S kilobytes Print sizes in kilobytes This overrides the environment variable POSIXLY_CORRECT count links Count the size of all files even if they have appeared already in another hard link summarize Display only a total for each argument one file system Skip directories that are on different filesystems from the one that the argument being processed is on dereference args Dereference symbolic links that are command line argu ments Does not affect other symbolic links This is helpful for finding out the disk usage of directories like usr tmp where they are symbolic links dereference Dereference symbolic links show the disk space used by the file or directory that the link points to instead of the space used by the link separate dirs Count the size of each directory separately not including the sizes of subdirectories help Print a usage message on standard output and exit successfully version Print version information on standard output then exit successfully
208. up by files in this directory and files reserved for the use of the super user are kept in this directory In most ways this is the same as and other user s home directory sbin is the system binary directory It contains binaries or programs used to administer the system for creating filesystems starting system services and other administrative tasks Binaries in sbin are similar across different Linux systems There is a similar directory usr sbin where binary programs for administering services specific to the instal lation are Another directory usr local sbin will contain binaries for custom installed programs that are not a part of the Linux distribution CONTENTS 6 tmp is a temporary directory Files that are not essential to the operation of the system temporary scratch files and other fast changing files are created in tmp usr is known as the users directory system wide applications libraries and documentation that are for the most part installed as part of the distribution are in this directory and it s subdirectories This is the users shared resource directory var contains many files that change often The subdirectories and files may remain somewhat constant but the contents of those files is dynamic Cache files spool files log files pid files are all to be found in var The print and mail spools are both in subdirectories of var Commands What is a command Command n Statement presented by a
209. ur input preprocessor a chance to modify the way the contents of the file are displayed An input preprocessor is simply an executable program or shell script which writes the contents of the file to a different file called the replacement file The contents of the replacement file are then displayed in place of the contents of the original file However it will appear to the user as if the original file is opened that is less will display the original filename as the name of the current file An input preprocessor receives one command line argument the original file name as entered by the user It should create the replacement file and when finished print the name of the replacement file to its standard output If the input preprocessor does not output a replacement filename less uses the original file as normal The input preprocessor is not called when viewing standard input To set up an input preprocessor set the LESSOPEN environment variable to a command line which will invoke your input preprocessor This command line should include CONTENTS 35 one occurrence of the string s which will be replaced by the filename when the input preprocessor command is invoked When less closes a file opened in such a way it will call another program called the input postprocessor which may perform any desired clean up action such as deleting the replacement file created by LESSOPEN This program receives two command line arguments
210. where previous search started Display current line number pattern Search for kth occurrence of regular expression Defaults to 1 n Search for kth occurrence of last r e Defaults to 1 lt cemd gt or lt cmd gt Execute lt cmd gt in a subshell v Start up usr bin vi at current line L Redraw screen n Go to kth next file Defaults to 1 p Go to kth previous file Defaults to 1 f Display current file name and line number Repeat previous command CONTENTS 55 ENVIRONMENT More utilizes the following environment variables if they exist MORE This variable may be set with favored options to more SHELL Current shell in use normally set by the shell at login time TERM Specifies terminal type used by more to get the terminal characteristics necessary to manipulate the screen SEE ALSO vi 1 less 1 AUTHORS Eric Shienbrood UC Berkeley Modified by Geoff Peck UCB to add under lining single spacing Modified by John Foderaro UCB to add c and MORE environment variable HISTORY The more command appeared in 3 0BSD This man page documents more ver sion 5 19 Berkeley 6 29 88 which is currently in use in the Linux community Documentation was produced using several other versions of the man page and extensive inspection of the source code EXAMPLES mount NAME mount mount a file system SYNOPSIS mount hV mount a fFursvw t vfstype O optlist mount fnrsvw o options
211. xecutable programs and in genereal how to find things on the system which shell to use and other im portant information about how the user can and will interact with the shell If a program doesn t exist in the PATH the shell cannot find and therefore cannot execute the program A common question among new users is why a command is not executed even though the user is in the same directory as the binary The answer is the shell knows nothing about binaries that are not in the PATH unless the full path to the binary is given on the command line This can be accomplished with several methods We ll demonstrate two First give the full path to the executable pwd home joe this_directory that_directory my_command The shell will execute my_command if the user has the proper permissions because the user has given the shell the full path to the executable Or if the command is in the current directory pwd this_directory that_directory my_command The tells the shell to execute my_command in the current directory To find out what is in your PATH do the following echo PATH usr local bin bin usr bin usr X11R6 bin home joeuser bin The order of the directories in PATH is significant It is the order which the shell will search for commands If there are commands in different directories with the same name the first command found will be executed This is im portant to know because it
212. ystem for Linux and a brief overview of managing runlevels We show you how to properly shutdown and reboot your system 101 CONTENTS 102 Boot floppy Did you make a boot floppy during your install Most distributions of Linux give you the opportunity to create a boot floppy during your install This is always a good idea Should you make a mistake like forgetting to run lilo after modifying etc lilo conf a boot disk would allow you to recover and get your system back in running order Have you been running as root against our better advice and removed part of your filesystem where your kernel is Have you installed a new kernel and fogotten to save your old running kernel as a fallback position All these scenarios are easier to recover from with a boot floppy Basically a boot floppy created during the install contains a kernel modules and ram disk that will work on your system It contains many of the same configuration information gathered during the install If you didn t create one during the install don t fret you can still create one now mkbootdisk Mkbootdisk is a program that allows you to create a stand alone boot floppy from a running system man mkbootdisk It s the same script that the installer uses to create one during the install The resulting boot disk is entirely self contained and includes an initial ramdisk image which loads any necessary SCSI modules for the system The created boot disk looks for

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