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1. if a file has this attribute set and is open for writing the only operation possible will be to append data to it s previous contents For a directory this means that you can only add files to it but not rename or delete any existing file Only root can set or clear this attribute 9 s secure deletion when such a file or directory with this attribute set is deleted the blocks it was occupying on disk are written back with zeroes similar to using shred Note that this does work on the ext2 and ext3 filesystems but is unlikely to work on others please see the documentation for the filesystem you are using You may also like to see shred please see Chapter 7 Isattr list attributes This will list if whether a file has any special attributes as set by chattr Use the R option to list recursively and try using the d option to list directories like other files rather than listing their contents Command syntax This will list files in the current directory you may also like to specify a directory or a file lsattr directory or file Chapter 14 Security 70 Chapter 15 Archiving Files The archiving files chapter provides some basic information on the simple programs that you can use to archive files You will often see these programs used when you try to install programs without using a package management tool This is not a backup guide Please note that while tar is useful for regular purposes
2. semicolon characters to do more and more commands on the one line Chapter 6 Directing Input Output 20 Chapter 7 Working with the file system The working with the file system chapter explains a number of commands that you use to move around the file system hierarchy and manipulate the files Also explained are finding files and how to mass rename files 7 1 Moving around the filesystem cd Is Change directory Use cd to go up one directory One dot represents the current directory while two dots represent the parent directory cd will return you to the previous directory a bit like an undo You can also use cd absolute path or cd relative path see below Absolute paths An absolute path is easily recognised from the leading forward slash The means that you start at the top level directory and continue down For example to get to boot grub you would type cd boot grub This is an absolute path because you start at the top of the hierarchy and go downwards from there it doesn t matter where in the filesystem you were when you typed the command Relative paths A relative path doesn t have a preceding slash Use a relative path when you start from a directory below the top level directory structure This is dependent on where you are in the filesystem For example if you are in root s home directory and want to get to root music you type gl sei Please note that there
3. A 3 8 AGGREGATION WITH INDEPENDENT WORKS eee eene 93 A 3 9 TRANSIEATION 2 5 3 nga pee oreet tei ER Ras dt tra pd 94 AS T0 TERMINATION oet efeathte eorr eet eo e eee n eee eae res erar Haee aedi cere epe ed 94 A 3 11 FUTURE REVISIONS OF THIS LICENSE eese nennen 94 h3ejiDruiei n deo 94 Chapter 1 Introduction This document is an attempt to summarise the many command line based tools available to a GNU Linux based operating system This guide is not a complete listing I doubt it s possible to document all available programs this document lists many tools which are available to GNU Linux systems and which are or can be useful to the majority of users Each tool description provides a quick overview of it s function and some useful options for that individual tool The tools listed that require a GUI usually the X windowing system are those listed in the Graphics Tools section All other tools are completely command line based and do not require a GUI to run If you are looking for information on GUI based tools you will need to look elsewhere Also note that a few of the tools in this guide are bash the Bourne Again SHell specific tools specific to other shells are not listed in this document For some of the tools that are harder to use or perform a more complex task there are several mini tutorials or mini guides Chapter 20 within this document Where a mini guide was considered
4. CTRL W This key combination can be used to cut or delete the entire line that has being typed 4 4 Virtual Terminals and screen Using the key combination ALT F keys you may change to different virtual terminals You will have several usually 6 virtual terminals setup with shells Number 7 is usually setup with X you need to use CTRL ALT F to change to a terminal from within X X as in the X windowing system screen Chapter 4 Shell Tips 13 GNU Linux Command Line Tools Summary is a great program that allows you to switch between multiple virtual terminals on the one physical terminal that you are using Its a command line based window manager clearly this isn t that useful if you do have virtual terminals but its amazingly useful when you log into machines remotely using ssh and similar see Section 13 3 It works on key combinations you type screen On the command line to begin Now you start with one virtual terminal by default but using the key combination CTRL A and then hitting C you can create another virtual terminal to use Use CTRL N to go to the next virtual terminal and CTRL P to go to the previous virtual terminal Also try hitting CTRL A to go backwards and forwards between two particular terminals screen also has various other abilities that you can test out The documentation and guides are well written so please feel free to read the manual page or try searching the internet Chapter 4 Shell Tips 14
5. Command syntax bzme filename i Tip Both gzip and bzip2 supply tools to work within compressed files for example listing the files within the archive running less on them using grep to find files within the archive et cetera For gzip the commands are prefixed with z zcat zless zgrep For bzip2 the commands are prefixed with bz bzcat bzless bzgrep Chapter 15 Archiving Files 73 Chapter 16 Graphics tools command line based The graphics tools chapter explains some image programs that can be called from the command line While I have found image programs that can be used from the command line zgv is the only one I ve ever heard of I did not find them very useful All the tools listed use the X windowing system to work and simply run from the command line so they can be scripted automated if necessary montage Creates a montage an image created of many other images arranged in a random fashion Command syntax montage r34 jpg r32 jpg skylines skyline images miff The above would create a montage of images it would tile a certain number of images into a composite image called skyline images miff you could always use display to view the image Note Note that the images are converted to the same size scaled so they can be tiled together convert To convert the file format of an image to another image format convert is used to change a files format for example from a jpeg to a bitmap or one of
6. GNU Linux Command Line Tools Summary Example ewwubee LO u 1xo9t This would increase the priority of all root s processes 9 4 Controlling services Concept Definitions UNIX systems use scripts to control daemons which provide services for example your sound output to run a UNIX system UNIX systems consist of a variety of services daemons A daemon is a system process which runs in the background zero interaction performing a particular task Daemons normally have a d on the end of their name and either listen for certain events or perform a system task for example sshd listens for secure shell requests to the particular machine and handles them when they occur Daemons usually perform critical system tasks such as control swap space memory management and various other tasks service service is a shell script available on Mandrake Mandriva and Redhat systems which allows you to perform various tasks on services Use the s option to print the status of all services available 9 Use the f option followed by a service name to restart that particular service Use the R option to restart all services note that this will kill any current services running including the X windows system For example to restart the daemon sshd you would type service f sshd Using the script directly You may also execute the shell script directly from etc init d Simply go to that directory then type J script n
7. The superuser This user has power over everything and all and can do anything with the system including destroy it and of course fix it This user is used to perform most administration functions on the system 10 1 Users Groups All user information is normally listed in the etc passwd file and the group information in the etc groups file If you need to edit either file it is recommended that you use vipw to edit the password file and vigr to edit the group file These particular commands take care of any processing and locking of the files before and after editing them There is a lot of information about adding removing controlling users and groups this information is only the minimal information required chsh Used to change your login shell To list the shells available type Chapter 10 Managing users 45 GNU Linux Command Line Tools Summary Chichi lec sinc Ibis Simply type chsh then Enter then type the name of the shell you would like to use every time you login chfn Change finger information The information this command changes is reflected in the etc passwd file use this utility to update your real name office and home phone numbers if they exist Use the f option to change a users full name Use this tool as either chfn or chfn user name usable by root only Command syntax chfn user name passwd Changes the password of a user You will need to be root if you want to chan
8. g This is a note Notes often give important information about a tool i This is a tip This will offer a useful switch or useful way to use a tool Q This is something important This is something that is considered very important Consider it like a note with extra importance they are usually there to save the reader time d This is a caution This will inform you of something that you be careful about because it could be harmful to your system amp This is a warning This will inform you of something that you shouldn t do because it probably will break something within your system code examples Code examples are shown for most commands Below is an example of what code looks like Hello World I m a code example command syntax or a similar phrase simply shows how you would normally use the command Often real examples are used instead of explaining the command syntax The phrase Command syntax is always followed by the way you would type a command in a shell The standard syntax for any tool is usually command options file g Note Note that some tools do not accept options wildcards Also note that most commands even when not explicitly stated will work with standard wildcards or globbing patterns such as A Z and various other standard wildcards Refer to Section 20 4 1 for further information access keys Access keys enable navigation through the document without relying on a mouse T
9. number all lines or cat b number all non blank lines For more info on cat check under this section Section 11 2 There are two ways you can use nl nl some text file txt The above command would add numbers to each line of some text file You could use nl to number the output of something as shown in the example below grep some string some file nl Perl search and replace text To search and replace text in a file is to use the following one line Perl command 4 perl pi e s oldstring newstring g filespec RET In this example oldstring is the string to search newstring is the string to replace it with and filespec is the name of the file or files to work on You can use this for more than one file Example To replace the string helpless with the string helpful in all files in the current directory type S peril oi s helpless helpful g RET Also try using tr to do the same thing see further above in this section If these tools are too primitive If these text tools are too simple for your purposes then you are probably looking at doing some programming or scripting If you would like more information on bash scripting then please see the advanced bash scripting guide authored by Mendel Cooper sed and awk are traditional UNIX system tools for working with text this guide does not provide an explanation of them sed works on a line by line basis performing substit
10. Chapter 5 Help The help chapter provides information on how you may access the documentation of the GNU Linux system There is normally a document describing every single tool you have installed even if its only brief man This command displays summary information on a program from an online manual For example typing man man will bring up the manual page for man the manual page viewer Note q is the quit key Command syntax man program name i Also try Specifying the section of the manual page sometimes the man page is different for the same tool in different sections note sections are numbered 1 to 9 Use apropos to find which section number to look in The syntax to look at a different section is For example This will show you the man page called time in section 2 the equivalent page in section 1 is completely different man K keyword Search the manual pages for a string as in it will search all manual pages for a particular string within each individual man page it will then prompt whether you would like to view each page it will find Use double quotes and if there are spaces in the string you are typing D Speed issue Please be warned that this method is going to be really really slow You are searching all man pages for a string man f command This will list details associated with the command The root user must run makewhatis see below before this command will work g Equivalent to whatis
11. GNU Linux Command Line Tools Summary Table of Contents Chapter 1 Introd ction eere esee et reo eroe roseo eee ette een te eto a Devo Fe pea eee Seos be tea os be Erates sa s Sop Sosson sos sioe edere Voors oS 1 1 1 Who would want to read this guide esessssseseeseeeeenee enne enne ener enne 1 1 2 Who would not want to read this guide sssssssssseeeeeeeeeeeen ene 2 1 3 Availability OE SOUFGCES 4 reete n e ette ei ERR He Pe He ETE dbveddersbinhacesbedeents 2 1 4 Conventions used in this Guide eeccecccecssecessecesseeceseeceeeeeceaeecaeceeaaeceaceceeaeeceeeeesaeeeeaeneaeeceeeeeaes 2 1 5 Resources used to create this document eese eene eene nhe etes sss nente eser eee 4 1 6 BeedDaclk 26 aec ete esee eee AE AEA E s tie de copie au Dies tnra erem rss 4 1 7 COMUMMIDULOTS ceret eere obe Meere E octaves oe eee ESE adeeb voc pac Neste De 5 LONE WIS ue M ESSE 7 PANSNEISEIISENEEURORN HIER 7 PSU Bet DU EET RURSUM HTC NA PA 7 Chapter 3 The Unix Tools Philosophy 4 ee ee ee eere eere seen eee tn sesto seen aee ta aee anas tense seen setae s snae seen sean 8 Chapter 4 Shell BREED 9 4 T General Shell Tips itn t epe e eee e a E E ENNO ee S ERUS 9 4 2 Th command line History y eee trente eee eere RA Te PR ERES RR pee ir eee DR RR 12 4 3 Other Key combinations ite eter LO tp e eie Dod es ee tai
12. General Shell Tips Automatic Command Completion alias Chapter 4 Shell Tips Use the TAB key and bash will attempt to complete the command for you automatically You can use it to complete command tool names You can also use it when working with the file system when changing directories copying files et cetera There are also other lesser known ways to use automatic command completion for example completing user names 1 ESC Y Y special character testing autoindexing Will attempt to complete the command name for you If it fails it will either list the possible completions if they exist If there are none it will simply beep and or flash the screen CTRL X Y Y special character Lists the possible completions it won t attempt to complete it for you or beep if there are no possible completions Special characters Use the following special characters combined with either ESC Y or CTRL X Y where Y is some special characters For example ESC or CTRL X to complete an environment variable name 9 tilde complete a user name at sign complete a machine name dollars sign complete an environment variable name exclamation mark a magic character for completing a command name or a file name The special character has the same function as the TAB key It works in some other situations for example when completing man page names The alias command will list your current aliases You can use u
13. Text Related Tools 49 GNU Linux Command Line Tools Summary sdiff Instead of giving a difference report it outputs the files in two columns side by side separated by spaces diff3 Same as diff except for three files comm Compares two files line by line and prints lines that are unique to filel 1st column unique to file2 2nd column and common to both files 3rd column Use comm with the 1 2 or 3 to suppress the printing of those particular lines Simply run comm to have all three listed ie unique to files 1 and 2 and common to both Command syntax Xon side 5 192 To output a list of words in the system dictionary that begin with a given string this is useful for finding words that begin with a particular phrase or prefix look Give the string as an argument it is not case sensitive Command syntax look string 11 4 Text manipulation tools i Also see Also see tac and cat over in this section Section 11 2 as they can perform text manipulation too sort Sorting text with no options the sort is alphabetical Can be run on text files to sort them alphabetically note it also concatenates files can also be used with a pipe l to sort the output of a command Use sort r to reverse the sort output use the g option to sort numerically ie read the entire number not just the first digit Examples Get Slaejoyouime Lisi sexe Soi The above command would run cat o
14. This command is the same as running whatis info Provides a more detailed hyper text manual on a particular command this only works for some commands Command syntax whatis Chapter 5 Help 15 GNU Linux Command Line Tools Summary Displays a one line description of what a program does The string needs to be an exact match otherwise whatis won t output anything Relies on the whatis database see below Command syntax whatis program name makewhatis Make the whatis database for apropos whatis and man f g Root Privileges This takes some time and you require root privileges to do this apropos Searches the whatis database for strings similar to whatis except it finds and prints anything matching the string or any part of the string Also relies on the whatis database see above Command syntax apropos string cg Equivalent to apropos is the same as doing man k lowercase k g Please note You need to run makewhatis as root so whatis man f and apropos will work i Also try Using a program with the h help and the h options they will display very short summary information on the command usage options Chapter 5 Help 16 Chapter 6 Directing Input Output The directing input output chapter explains how you can use a program and send its output to a file or to another command that you wish to use This technique is very powerful and there are a number of ways of doin
15. Use head n x where x is a number to display the first x lines Try head F to use a continually updated version of head if the file changes it will be reloaded and displayed please note that using this option will run head is a continuous loop so you ll need to use CTRL C to exit For example head n 20 somelog txt Will display the top 20 entries of the file somelog txt With no options it shows the last ten lines of a file Use tail n x where x is a number to display the last x lines Try tail F to use a continually updated version of tail 1f the file changes it will be reloaded and displayed please note that using this option will run tail is a continuous loop so you ll need to use CTRL C to exit Chapter 11 Text Related Tools 47 less more cat tac GNU Linux Command Line Tools Summary For example tail n 20 somelog txt Will display the last 20 entries of the file somelog txt Views text can scroll backwards and forwards Has many different options which are all described in the manual page When less is already running use n and p type a colon then the character to move to the next and previous files when there are multiple open files Command syntax less filename txt Or using a tool in this example cat can PLlerext EIS S Displays text one page full at a time more limited than less In this case Jess is better than more more filename txt Or usi
16. Version A Use in the Title Page and on the covers if any a title distinct from that of the Document and from those of previous versions which should if there were any be listed in the History section of the Document You may use the same title as a previous version if the original publisher of that version gives permission B List on the Title Page as authors one or more persons or entities responsible for authorship of the modifications in the Modified Version together with at least five of the principal authors of the Document all of its principal authors if it has less than five C State on the Title page the name of the publisher of the Modified Version as the publisher D Preserve all the copyright notices of the Document E Add an appropriate copyright notice for your modifications adjacent to the other copyright notices F Include immediately after the copyright notices a license notice giving the public permission to use the Modified Version under the terms of this License in the form shown in the Addendum below G Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document s license notice H Include an unaltered copy of this License I Preserve the section entitled History and its title and add to it an item stating at least the title year new authors and publisher of the Modified Version as given on the Title Page If there is no section entitle
17. a list all processes from all users 9 u list more information including user names cpu usage and mem usage et cetera 9 x list processes without controlling terminals 9 display different information including UID and nice value 0 forest this makes it easier to see the process hierarchy which will give you an indication of how the various processes on your system interrelate although you should also try pstree For example to list all running processes with additional information simply type Displays the processes in the form of a tree structure similar to how free does it for directories Use the p option to show process id s Example This would list all processes and their id s This command is useful for finding the process id of a particular process when you know part of its name Use the option to list the name of the process as well and the u option to search via a particular user s Normally pgrep will only return the pid number this way you can use it with other commands Examples Chapter 9 Controlling the system 40 top kill killall GNU Linux Command Line Tools Summary kill pgrep mozilla This would kill any process name that starts with mozilla Note that this is the same as using pkill see below If you are unfamiliar with the part of this command please refer to Section 6 4 To list processes id s and names type pgrep l
18. an otherwise Transparent file format whose markup has been designed to thwart or discourage subsequent modification by readers is not Transparent A copy that is not Transparent is called Opaque Examples of suitable formats for Transparent copies include plain ASCII without markup Texinfo input format LaTeX input format SGML or XML using a publicly available DTD and standard conforming simple HTML designed for human modification Opaque formats include PostScript PDF proprietary Appendix A Appendix 90 GNU Linux Command Line Tools Summary formats that can be read and edited only by proprietary word processors SGML or XML for which the DTD and or processing tools are not generally available and the machine generated HTML produced by some word processors for output purposes only The Title Page means for a printed book the title page itself plus such following pages as are needed to hold legibly the material this License requires to appear in the title page For works in formats which do not have any title page as such Title Page means the text near the most prominent appearance of the work s title preceding the beginning of the body of the text A 3 3 VERBATIM COPYING You may copy and distribute the Document in any medium either commercially or noncommercially provided that this License the copyright notices and the license notice saying this License applies to the Document are reproduced in all copies and that
19. careful when using shred as you may never be able to retrieve the data you have run the application on For example shred n 2 z v dev hdal What this tells shred is to overwrite the partition 2 times with random data n 2 then finish it up by writing over it with zeroes z and show you its progress v Of course change dev hdal to the correct partition Each pass can take some time which is why I set it to only do 2 random passes instead of the default 25 You can adjust this number of course to your particular level of paranoia and the amount of time you have Since shred writes on such a low level it doesn t actually matter what kind of filesystem is on the partition everything will be unrecoverable Once shred is finished you can shutdown the machine and sell or throw away the drive with peace of mind However even shre dding devices is not always completely reliable For example most disks map out bad sectors invisibly to the application if the bad sectors contain sensitive data shred won t be able to destroy it shred info page 2 Shredding files doesn t work with all filesystems Please note that as mentioned in the shred manual page please see the manual and preferably info pages for more information shred does not work correctly on log structured or journaled filesystems such as JFS ReiserFS XFS Ext3 and many other modern filesystems i Alternatives to using shred
20. contributors section Section 1 7 for specific details 1 6 Feedback Feedback is necessary for the advancement of this guide Positive constructive criticism is encouraged If you have ideas suggestions advice or problems with this guide please send an email to the author Gareth Anderson D Contributions If you wish to make contributions it is recommended if possible to read the LyX file s for this document They contain various notes which you can t see in the other versions These notes highlight the areas that need contributions certain tools which I cannot understand tools which have not been added or tools which were removed These notes also explain some of the structure of this document Chapter 1 Introduction 4 GNU Linux Command Line Tools Summary 1 7 Contributors As you may be able to see parts of this guide are based off various advice columns on GNU Linux anything that has being directly quoted from an article can be found in the references Bibliography section of this document The following is a list of people who have made a significant contribution to this document in a rough chronological order Chris Karakas Chris allowed the use of his lyxtox scripts to convert the LyX file of the document to working DocBook SGML output to learn how to use the lyxtox scripts yourself see Document processing with LyX and SGML Chris provided useful suggestions and advice and added an index listi
21. day part the 5th place with an asterisk it would mean everyday Lists are allowed A list is a set of numbers or ranges separated by commas Examples 1 2 5 9 7 0 4 8 12 Step values can be used in conjunction with ranges Following a range with number specifies skips of the number s value through the range For example 0 23 2 can be used in the hours field to specify command execution every other hour the alternative in the V7 standard is 770 2 4 6 8 10 12 14 16 18 20 22 Steps are also permitted after an asterisk so if you want to say every two hours just use 2 When writing a crontab entry you simply type in six fields separated by spaces the first five are those listed in the table using numbers or letters and numbers as appropriate the 6th field is the command to be executed and any options cron will read everything up until the newline Example 5 4 sun echo run at 5 after 4 every sunday Chapter 18 Scheduling Commands to run in the background 78 GNU Linux Command Line Tools Summary This would run the echo command with the string shown at 4 05 every Sunday Chapter 18 Scheduling Commands to run in the background 79 Chapter 19 Miscellaneous The miscellaneous chapter contains commands that don t really fit into the other sections of this guide renaming extensions To rename all of the files in the current directory with a htm extension to html type chease x s
22. designed to get information from standard input only For example using tr ipe U AS Za a anali xe EENES TE 2 meealkeN ameNew ete sate The example above would insert the contents of fileName txt into the input of tr and output the results to fileNameNew txt gt gt The gt gt symbol appends adds information to the end of a file or creates one if the file doesn t exist lt lt The lt lt symbol is sometimes used with commands that use standard input to take information You Chapter 6 Directing Input Output 17 2 tee GNU Linux Command Line Tools Summary simply type word where word can be any string at the end of the command However its main use is in shell scripting The command takes your input until you type word which causes the command to terminate and process the input Using lt lt is similar to using CTRL D EOF key except it uses a string to perform the end of file function This design allows it to be used in shell scripts For example type cat with no options and it will work on standard input To stop entering standard input you would normally hit CTRL D As an alternative you can type cat lt lt FINISHED then type what you want When you are finished instead of hitting CTRL D you could type FINISHED and it will end the word FINISHED will not be recorded Redirects error output For example to redirect the error output to dev null so you do not see it simply a
23. download say anything that ends with pdf as well than add a A pdf before the website address Simply change the website address and the type of file being downloaded to download something else Note that doing A gif is the same as doing A gif double quotes only single quotes will not work wget has many more options refer to the examples section of the manual page this tool is very well documented Alternative website downloaders You may like to try alternatives like httrack A full GUI website downloader written in python and available for GNU Linux curl is another remote downloader This remote downloader is designed to work without user interaction and supports a variety of protocols can upload download and has a large number of tricks work arounds for various things It can access dictionary servers dict ldap servers ftp http gopher see the manual page for full details Chapter 13 Network Commands 63 GNU Linux Command Line Tools Summary To access the full manual which is huge for this command type Kee EVI For general usage you can use it like wget You can also login using a user name by using the u option and typing your username and password like this curl u username password http www placetodownload file To upload using ftp you the T option bue iL i eile nane jte Ego o Uiolioverela i te s eonun To continue a file use the C option curl C o file htt
24. ete de Lebe ena ete odes eee ba e re dede 49 11 4 Text manipulation tools o reve tre dere rii bag e P EYE EE ERE e SERA 50 11 5 Text Conversion Filter Tools eese ertet tenen enne nnn a eet es nana aea tet a asa betonte 54 PUD ch C onverston tools s code eter crt eoo ee o Bese Gale buted eet eee caro eese A dern caet 56 11 6 Finding Text Within Files eei eee eR here eee ele eee Lee ien 57 Chapter 12 Mathematical tools c cccccssicccsesisscssssesssscsssssessdsssesonssdoaedsssesesncsSacdeesdessossseesecesseaidesoseeesssueseossesseess 58 Chapter 13 Network Commands ssciiseiccisccacctsssssaccesecosacsesssessoncesonscssnasensesssuadessenseensossaescsedsesscetssoetesnsesseessosses 60 13 1 Network C onfigur tion dato er He PORE TU Mrs POE Ee Peg Ren 61 13 2 Internet Specific Commands iio eterne tt URL ne a aah 62 13 3 Remote Administration Related oeeseeesessesssecessoossesssecsesrcrecssssesscosssessesseseosssoseesessesecosssessecess 64 Chapter 14 SOCurit ye seccscecissessssecesssccssosasessesesessdesnssensontesesssdssencsevecssasessessssedessossbosnssseessoasteseses soatosecesessssssees 66 14 1 Some basic Security Tools abe e testers er ERE EQ Hab ota a spe tbe ed eae 67 14 2 File Permissions eroe coe te rote E EE Dti beber ti se eoi tbe A la caece staves bah bees ee dere oo sa 67 Chapter 15 Archiving Piles TORTE 71 15 3 t r tape archiver inde e A sn a eA els 71 DDD TS VIG ceren
25. many other formats convert can also manipulate the images as well see the man page or the ImageMagick site Example from Jpeg to PNG format EG thisfile jpg PNG thisfile png import Captures screen shots from the X server and saves them to a file A screen dump of what X is doing Command syntax import file name display display is used to display output images on the screen Once open you are can also perform editing functions and are able to read write images It has various interesting options such as the ability to display images as a slide show and the ability to capture screenshots of a single window on screen Command syntax for displaying an image display image name To display a slide show of images open the images you want possibly using a wildcard for example display jpg And then click on the image to bring up the menu and then look under the miscellaneous menu for the slide show option d Speed Warning Chapter 16 Graphics tools command line based 74 identify mogrify GNU Linux Command Line Tools Summary Be careful when opening multiple large sized images especially on a slow machine and putting the slide show on a small delay between image changes Your processor will be overloaded and it will take a significant amount of time to be able to close ImageMagick Will identify the type of image as well as it s size colour depth and various other information Use the verbose o
26. number 9 anywhere within it s name Chapter 20 Mini Guides 84 GNU Linux Command Line Tools Summary 20 4 3 Useful categories of characters as defined by the POSIX standard This information has been taken from the grep info page with a tiny amount of editing see 10 in the Bibliography for further information upper uppercase letters lower lowercase letters e alpha alphabetic letters meaning upper lower both uppercase and lowercase letters e digit numbers in decimal 0 to 9 e alnum alphanumeric meaning alpha digits any uppercase or lowercase letters or any decimal digits e space whitespace meaning spaces tabs newlines and similar e graph graphically printable characters excluding space e print printable characters including space e punct punctuation characters meaning graphical characters minus alpha and digits e cntrl control characters meaning non printable characters e xdigit characters that are hexadecimal digits g These are used with The above commands will work with most tools which work with text for example tr For example advanced example this command scans the output of the dir command and prints lines containing a capital letter followed by a digit ig mee Il swrepexs l Jl seus Ip The command greps for upper case letter any digit meaning any uppercase letter followed by any digit If you remove the square brackets in the m
27. number of his criticisms were addressed and improved George Harmon George provided a second language review His detailed review of the material allowed me to improve the general grammar of the document and some minor errors Machtelt Garrels tille Machtelt provided tips in regard to referencing the correct LDP documents from this guide As well as general advice on improvements to the guide Michael Kerrisk Chapter 1 Introduction 5 GNU Linux Command Line Tools Summary Michael pointed out a number of technical errors in the document after his brief review on behalf of the TLDP during posts to the discussion list Chapter 1 Introduction Chapter 2 Legal The legal chapter provides information about the disclaimer that applies to the entire document and the licensing information 2 1 Disclaimer No liability for the contents of this document can be accepted Use the concepts examples and other content at your own risk There may be errors and inaccuracies that may of course be damaging to your system Although this is highly unlikely you should proceed with caution The author does not accept any responsibility for any damage incurred All copyrights are held by their respective owners unless specifically noted otherwise Use of a term in this document should not be regarded as affecting the validity of any trademark or service mark Naming of particular products or brands should not be seen as endorsements UNIX is a re
28. option s optional directory to list 7 1 1 Finding files find find is a tool which looks for files on a filesystem find has a large number of options which can be used to customise the search refer to the manual info pages Note that find works with standard wildcards Section 20 4 1 and can work with regular expressions Section 20 4 2 Basic example find name file This would look for a file named file and start at the root directory it will search all directories including those that are mounted filesystems The name option is case sensitive you can use the iname option to find something regardless of case Use the regex and iregex to find something according to a regular expression either case sensitive or case insensitive respectively The exec option is one of the more advanced find operations It executes a command on the files it finds such as moving or removing it or anything else To use the exec option use find to find something then add the exec option to the end then command to be executed o then curly brackets e then the arguments for example a See below for an example of use this command This is the tool you want to execute on the files find locates For example if you wanted to remove everything it finds then you would use exec rm f The curly brackets are used in find to represent the current file which has been found ie If it found
29. process name Displays the top as in CPU usage processes provides more detail than ps top also provides an updated display it has many options that make it fully customisable refer to the manual or info page for details To kill processes on your system you will need their pid s or id s Use ps or pstree to find out the process id s pid s or use jobs to find out id s i killall and pkill kill a process by name pkill and killall can be a lot easier to use than kill pkill allows you to type part of the name of a process to kill it while killall requires the full process name See below for more information Examples kill pid Simply kill a process allow it time to save it s files and exit kill id Same as above except it uses an id instead of a pid you need to use a percent when using an id to kill Force a process to be killed won t allow files to be saved or updated only use when necessary because all data that the program had will be lost There are also many other kill options such as kill HUP hangup refer to the manual info pages for more information Kill a process by it s name uses names instead of process id s pid s Use v to have killall report whether the kill was successful or not and i for interactive mode will prompt you before attempting to kill pkill a little like a killall with regular expressions pkill is another command that allows processes to be kil
30. s Use the rpm V option to check whether or not a package has been modified For example rpm V textutils If none of the files from the textutils package have changed then rpm will exit without outputting any data If on the other hand the program has changed you may see something like this 55 5551 nou ceu This isn t as cryptic as it appears The line returned from rpm V contains any number of eight characters plus the full path to the file Here are the characters and their meaning 12 e S File size differs e M Mode differs includes permissions and file type e 5 MDS sum differs e D Device major minor number mis match e L ReadLink 2 path mis match e U User ownership differs e G Group ownership differs e T mTime differs i Mandriva Users Note Mandriva Linux uses a customised version of RPM called urpmi It consists of the urpm commands urpmi to install urpme to remove and urpmf and urpmq to query This customised version has advantages over standard RPM including automatic dependency solving and Debian apt get style functions ability to download programs over the internet and have all dependencies resolved automatically The urpm commands are all described in detail in Mandriva s documentation and various sources online 20 2 Checking the Hard Disk for errors Checking the hard disk for errors on your primary drive is very very
31. shutdown h now Warning system malfunction self destruct imminent This would halt the system and send the message to anyone who is currently logged in i Shutting down at a particular time You can also put a time that the system should shutdown instead of now Typing x minutes any number of minutes is appropriate or you can even set an exact time For example to shutdown at 11 50 type Slaibneclexyiay lei Lil 5 0 H Shutdown h vs poweroff On some systems shutdown h and halt do not actually turn the system s power off On systems that do not power off with these commands use the poweroff command halt The same as shutdown h now doesn t take any options this command simply shuts down immediately shutdown r now Shutdown r reboot the computer immediately It begins the reboot procedure press CTRL C break key to stop it After the end of the command you can also leave a message in quotation marks which will be broad casted to all users for example shutdown r now Warning system rebooting all files will be destroyed This would reboot the system and send the message to anyone who was logged in i Rebooting at a particular time You can also put a time that the system should reboot instead of now Typing x minutes any number of minutes is appropriate or you can even set an exact time For example to reboot at 11 50 type Sauterin 31 JUL g 0 reboot The same as shutdown r now doesn
32. t take any options simply reboots the computer immediately CTRL ALT DEL key combination May be used from a terminal to reboot or shutdown it depends on your system configuration Note that this doesn t work from an xterminal CTRL ALT DEL begins the reboot shutdown immediately the user does not have to be logged in i You can change the behaviour of CTRL ALT DEL from rebooting To disable CTRL ALT DEL from rebooting your computer or to have it do something different you can edit the etc inittab file as root Here is how it looks on a Mandrake Mandriva Linux system Chapter 9 Controlling the system 39 GNU Linux Command Line Tools Summary Trap CTRL ALT DEL ca ctrlaltdel sbin shutdown t3 r now Note that the means a comment and is not used If you simply put a hash before the command it would disable it it would become a comment You could also change the command it runs for example if you changed the r to a h the computer would turn off instead of rebooting or you could have it do anything you want It s up to your creativity to make it do something interesting 9 3 Controlling Processes ps pstree pgrep Will give you a list of the processes running on your system With no options ps will list processes that belong to the current user and have a controlling terminal Example options include 9 aux list all running processes by all users with some information 9
33. the description of the mogrify tool in particular the example on creating thumbnails 18 Kyle Rankin Please For the Love of All That s Recoverable Shred Your Hard Drive This particular article by Kyle Rankin was used only a paragraph for information on the shred command Appendix A Appendix 96
34. the file shopping doc then would be substituted with shopping doc It would then continue to substitute for each file it finds The brackets are normally protected by backslashes X or single quotation marks to stop bash expanding them trying to interpret them as a special command eg a wildcard e This is the symbol used by find to signal the end of the commands It s usually protected by a backslash Y or quotes to stop bash from trying to expand it find name doc exec cp tmp The above command would find any files with the extension doc and copy them to your tmp directory obviously this command is quite useless it s just an example of what find can do Note that the quotation marks are there to stop bash from trying to interpret the other characters as something Excluding particular folders with find can be quite confusing but it may be necessary if you want to search your main disk without searching every mounted filesystem Use the path option to exclude the particular folder note you cannot have a forward slash on the end and the prune option to Chapter 7 Working with the file system 23 GNU Linux Command Line Tools Summary exclude the subdirectories An example is below fimo 7 para mirava g xum 9 meme Vgnpregaegp jorealieve This example will search your entire directory tree everything that is mounted under it excluding mnt win_c and all of the subdirect
35. tutorials under the power commands section of the unix about com site were used in the construction of this guide In particular parts of the xargs command Chapter 8 and parts of the cut command Section 11 4 were used from their tutorials 7 MandrakeSoft Command Line Manual MandrakeSoft The Command Line Manual developed for Mandake Linux 9 0 was used in the creation of this document A small section in regard to command line completion was used from this document If you are running mandrake you will most likely find this guide here 8 MandrakeSoft Starter Guide MandrakeSoft The MandrakeSoft Starter Guide a guide developed for Mandake Linux 9 0 was used in the creation of this document A small section in regard to how to recover from a system freeze was used from this document If you are running a mandrake system you will most likely find the document here 9 Hrvoje Niksic Wget Manual page Free Software Foundation A section of the wget manual page was used in this guide from this page Wget Manual page In particular relating to downloading multiple files while using the http protocol 10 Grep Free Software Foundation Appendix A Appendix 95 GNU Linux Command Line Tools Summary Both wildcards subsections are based off the grep manual and info pages The Useful Categories of Characters as defined from the POSIX standard was taken from the grep info page 11 Marc Ewing Jeff Johnson and Erik Troan RPM Man
36. unncessary detailed descriptions that explain in detail how a particular tool works and some examples of how to use it are provided Please note that the word tool is used interchangeably with the word command both have the same meaning at least in this guide For a more detailed explanation read about the UNIX Tools Philosophy here Chapter 3 or visit the links in the appendix Section A 2 2 1 i To find out which tools are bash specific To find out which tools are bash specific you can type 1 1 Who would want to read this guide Anyone who is interested in learning about the tools also known as commands available to them when using their GNU Linux based operating system Why would you want to learn how to use the command line and available tools The Command Line Jnterface CLI while difficult to learn is the quickest and most efficient way to use a computer for many different tasks The CLI is the normal method of use for most UNIX system administrators programmers and some power users While a GUI is better suited to some tasks many operations are best suited to the CLI The major motivation behind learning the GNU Linux CLI is the authors idea that with software in general the more time spent learning something equals less time spent performing that particular task authors opinion only Chapter 1 Introduction 1 GNU Linux Command Line Tools Summary This guide is aimed at beginners to intermediate users
37. who want to learn about the command line tools available to them Advanced users may wish to use it as a command reference however this document aims to list commands of interest as judged by the authors opinion it is not designed to be completely comprehensive see the appendix Section A 2 1 for further information Or if you are not looking for a command reference guide but a more gentle introduction to GNU Linux you may be interested in the Introduction to Linux guide authored by Machtelt Garrels This guide could also be considered a summarised version of the Linux Cookbook If you are looking for a book with more detailed descriptions of each tool have a look at the Linux Cookbook Homepage also check out the command list from Linux in a Nutshell 3rd Edition for an index of 300 commands and their explanations 1 2 Who would not want to read this guide Anyone who is not interested in the command line or anyone looking for a detailed reference to all available GNU Linux tools should look elsewhere This is only a summary while it does list many commands it s not a complete listing I don t think it s possible to make a complete listing anyway This document would not be of interest to those who already have an expert knowledge of the command line interface and do require any reference information Or those readers who require detailed lists of options for each command the man pages are better suited to this purpose 1 3 Availabi
38. wish to remove things according to tabs or commas or anything else you can think of Options for cut d allows you to specify another delimiter for example is often used with etc passwd cut d and probably some more options here etc passwd f this option works with the text by columns separated according to the delimiter For example if your file had lines like result somethingelse somethingelse and you only wanted result you would use Cine e s f 1 etc passwd This would get you only the usernames in etc passwd 0 commas used to separate numbers these allow you to cut particular columns For example dt Tet e assw This would only show the username and the shell that each person is setup for in etc passwd hyphen used to show from line x to line y for example 1 4 would be from lines 1 to line 4 guit e 1 290 acudel s This would cut display characters columns 1 to 50 of each line and anything else on that line is ignored Q x where x is a number to cut from line 1 to x 0 x where x is a number to cut from x to the end cuk S OOS fe ibl EE This would display cut characters columns 1 to 5 8 and from 20 to the end a c Pr ispell aspell To spell check a file interactively prompts for you to replace word or continue aspell is said to be better at suggesting replacement words but its probably bes
39. you add no other conditions whatsoever to those of this License You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute However you may accept compensation in exchange for copies If you distribute a large enough number of copies you must also follow the conditions in section 3 You may also lend copies under the same conditions stated above and you may publicly display copies A 3 4 COPYING IN QUANTITY If you publish printed copies of the Document numbering more than 100 and the Document s license notice requires Cover Texts you must enclose the copies in covers that carry clearly and legibly all these Cover Texts Front Cover Texts on the front cover and Back Cover Texts on the back cover Both covers must also clearly and legibly identify you as the publisher of these copies The front cover must present the full title with all words of the title equally prominent and visible You may add other material on the covers in addition Copying with changes limited to the covers as long as they preserve the title of the Document and satisfy these conditions can be treated as verbatim copying in other respects If the required texts for either cover are too voluminous to fit legibly you should put the first ones listed as many as fit reasonably on the actual cover and continue the rest onto adjacent pages If you publish or distribute Opaque copies of the Document numbe
40. GIONE VES EE EIE C URE SITIO CIT done The above script renames files using a built in bash function For more information on bash scripting you may like to see the advanced bash scripting guide authored by Mendel Cooper Chapter 7 Working with the file system 31 Chapter 8 Finding information about the system time proc dmesg df who If you are looking for how to change the time please refer to date here Section 8 1 time is a utility to measure the amount of time it takes a program to execute It also measures CPU usage and displays statistics Use time v verbose mode to display even more detailed statistics about the particular program Example usage time program name options The files under the proc process information pseudo file system show various information about the system Consider it a window to the information that the kernel uses For example cat proc cpuinfo Displays information about the CPU less proc modules Use the above command to view information about what kernel modules are loaded on your system dmesg can be used to print or control the kernel ring buffer dmesg is generally used to print the contents of your bootup messages displayed by the kernel This is often useful when debugging problems Simply type dmesg Displays information about the space on mounted file systems Use the option to have df list the space in a human readable for
41. GNU Linux Command Line Tools Summary Gareth Anderson lt somecsstudent at gmail com gt Chris Karakas Conversion from LyX to DocBook SGML Index generation Revision History Revision 1 2 15th April 2006 Revised by GA Corrected typing errors generated new much smaller index more accurate in my opinion Updated errors in document for TLDP Revision 1 1 28th February 2006 Revised by CK Corrected typos generated new index 9000 index entries Revision 1 0 6th February 2006 Revised by GA Major restructuring now in a docbook book format Removed large chunks of content and revised other parts removed chapters and sectioned some areas more This is likely the final release by the author I hope that someone finds this guide useful as I do not intend to continue work on this guide Revision 0 7 1 25th February 2005 Revised by CK Set special characters in math mode produced PDF and PS with Computer Modern fonts in OT1 encoding and created correct SGML for key combinations Revision 0 7 5th December 2004 Revised by GA Updated document with new grammatical review Re ordered the entire Text section Removed a fair amount of content Revision v0 6 20th April 2004 Revised by GA Attempted to fix document according to TLDP criticisms Added notes and tips more sectioning Now complying to the open group standards for the UNIX system trademark Document should be ready for TLDP site Revision v0 5 6th October 2003 Revise
42. ame Executing the script should return the options it can take by default they will be 9 restart this will make the service stop and then start again 9 start this option will start a service assuming its not running 9 stop this option will stop a service assuming its running 9 status this option will tell you about the service Chapter 9 Controlling the system 44 Chapter 10 Managing users su username Switch User change to a different user Use su to switch to root or su username to switch to a different username i Using sudo Its often considered better practice to use the sudo command rather than switch to the root user The sudo command allows you to perform actions as root but logs the actions you take so you can trace anything that was done to the system by yourself or others sudo has a very good manual page which provides plenty of information about it You use sudo similar to how you execute a normal command with sudo prepended to it for example sudo rpm U myrpm i386 rpm This would allow you to install a rpm even if you have the correct sudo access Note that if you want to return to your original user you don t use su again type exit or press CTRL D Simply typing su will give you some root privileges but there are minor complications relating to environment variables It s generally considered better practice to use su because it has no restrictions root
43. and possibly combined with bash sciprting or similar it can become useful it is not a great program for performing real backups of data You should try searching the internet if you are looking for backup programs on GNU Linux or try Sourceforge or Freshmeat for programs that you can use You may also like to see rsync Section 15 2 15 1 tar tape archiver Type tar then option s Options list e c create e y verbose give more output show what files are being worked with extracted or added e f file create or extract from file should always be the last option otherwise the command will not work e 7 put the file though gzip or use gunzip on the file first e x extract the files from the tarball e p preserves dates permissions of the original files e j send archive through bzip2 e exclude pattern this will stop certain files from being archived using a standard wild card pattern or a single file name tar examples tar cvpf name of file tar files to be backed up This would create a tape archive no compressing peus ZAxeypudt dy deu stile eut This would extract files verbosely from a gzipped tape archive 15 2 rsync rsync rsync is a replacement for the old rcp remote copy command It can use ssh for encryption and is a very flexible tool it can copy from local machine to local machine from l
44. are the username and group respectively chmod Change file access permissions for a file s There are two methods to change permissions using chmod letters or numbers Letters Method Chapter 14 Security 67 chown GNU Linux Command Line Tools Summary use a or plus or minus sign to add or remove permissions for a file respectively Use an equals sign to specify new permissions and remove the old ones for the particular type of user s You can use chmod letter where the letters are a all everyone u user g group and o other Examples chmod u rw somefile This would give the user read and write permission chmod o rwx somefile This will remove read write execute permissions from other users doesn t include users within your group chmod atr somefile This will give everyone read permission for the file chmod a rx somefile This would give everyone execute and read permission to the file if anyone had write permission it would be removed Numbers Method you can also use numbers instead of letters to change file permissions Where r read 4 w write 2 x execute 1 Numbers can be added together so you can specify read write execute permissions read write 6 read execute 5 read writet execute 7 x 5 se o we chmod 777 somefile This would give everyone read write execute permission on this file The first number is user second is group and third is
45. arks although you may need to use both i The TAB Key Please note that using the TAB key automatic command completion will automatically use escapes for spaces so you don t have to type them manually The script command creates a typescript or capture log of a shell session it writes a copy of your session to a file including commands you type and their output tilde character The tilde character is used as an alias to a users home directory For example if your user name was fred instead of typing cd home fred you could simply type cd Or to get to fred s tmp directory under his home directory you could type cd tmp i Home directory shortcut tilde can also be used as a shortcut to other users home directories simply type user_name and it will take you to the users home directory Note that you need to spell the username exactly correct no wildcards set bell style none reset exit logout echo This particular set command will turn off the system bell from the command line use xset b for X windows If you want the bell to stay off pernamently no audible bell then you can add this command to your bashrc or bash profile just add it to the same one you have your alises in The reset command re initializes your current terminal This can be useful when the text from your terminal becomes garbled simply type reset and this will fix your terminal Closes your curren
46. art python in interactive mode simply type python Once python is started you can use it to add up sums or maybe do some python programming Use CTRL D end of file key to exit the Python interpreter numgrep A little bit like grep only this is designed for numbers only Use forward slashes to contain each expression Use m lt n gt to find multiples of the number n and use f lt n gt to find factors of the number n Use commas to seperate expressions and two dots to represent a range For example to input from standard input you could simply type Chapter 12 Mathematical tools 58 GNU Linux Command Line Tools Summary To input from a file and look for numbers between 1 and 1000 you could type numgrep 1 1000 file name g This tool comes from the num utils package Please note that this tool is part of the num utils package Chapter 12 Mathematical tools 59 Chapter 13 Network Commands The network commands chapter explains various tools which can be useful when networking with other computers both within the network and accross the internet obtaining more information about other computers This chapter also includes information on tools for network configuration file transfer and working with remote machines netstat Displays contents of proc net files It works with the Linux Network Subsystem it will tell you what the status of ports are ie open closed waiting masquerade connections It wi
47. c but won t remove a file with the number 9 anywhere within it s name backslash is used as an escape character i e to protect a subsequent special character Thus searches for a backslash Note you may need to use quotation marks and backslash es 20 4 2 Regular Expressions Regular expressions are a type of globbing pattern used when working with text They are used for any form of manipulation of multiple parts of text and by various programming languages that work with text For more information on regular expressions refer to the manual page or try an online tutorial for example IBM Developerworks using regular expressions For the manual page type Chapter 20 Mini Guides 83 GNU Linux Command Line Tools Summary Type man 7 regex g Regular expressions can be used by Regular Expressions are used by grep and can be used by find and many other programs i Tip If your regular expressions don t seem to be working then you probably need to use single quotation marks over the sentence and then use backslashes on every single special character dot will match any single character equivalent to question mark in standard wildcard expressions Thus m a matches mpa and mea but not ma or mppa backslash is used as an escape character i e to protect a subsequent special character Thus searches for a backslash Note you may need to use quotation marks and backslash es dot and aste
48. d History in the Document create one stating the title year authors and publisher of the Document as given on its Title Page then add an item describing the Modified Version as stated in the previous sentence J Preserve the network location if any given in the Document for public access to a Transparent copy of the Document and likewise the network locations given in the Document for previous versions it was based on These may be placed in the History section You may omit a network location for a work that was published at least four years before the Document itself or if the original publisher of the version it refers to gives permission K In any section entitled Acknowledgements or Dedications preserve the section s title and preserve in the section all the substance and tone of each of the contributor acknowledgements and or dedications given therein L Preserve all the Invariant Sections of the Document unaltered in their text and in their titles Section numbers or the equivalent are not considered part of the section titles M Delete any section entitled Endorsements Such a section may not be included in the Modified Version N Do not retitle any existing section as Endorsements or to conflict in title with any Invariant Section If the Modified Version includes new front matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document you may at your option
49. d by GA Fixed a variety of errors as according to the review and made some consistency improvements to the document Revision v0 4 15th July 2003 Revised by GA Made small improvements to the document as suggested so far by the thorough TLDP review improved consistency of document and made small content additions Revision v0 3 26th June 2003 Revised by GA Minor errors fixed updated the appendix with information for finding where a tool is from Fixed referencing citation problems and improved further reading and intro sections added an audio section Revision v0 2 20th April 2003 Revised by GA This is the initial public release Added more code style then before broke text section into more subsections Improved consistency of document and fixed various index entries Revision v0 1 27th March 2003 Revised by GA This is the initial draft release the first release to be converted from LyX to DocBook SGML This document is an attempt to provide a summary of useful command line tools available to a GNU Linux based operating system the tools listed are designed to benefit the majority of users and have being chosen at the authors discretion This document is not a comprehensive list of every existent tool available to a GNU Linux based system nor does it have in depth explanations of how things work It is a summary which can be used to learn about and how to use many of the tools available to a GNU Linux based operating system
50. d makes it easier for normal users to use cron i Anacron anacron is another tool designed for systems which are not always on such as home computers While cron will not run if the computer is off anacron will simply run the command when the computer is next on it catches up with things Chapter 18 Scheduling Commands to run in the background 77 GNU Linux Command Line Tools Summary crontab is used to edit read and remove the files which the cron daemon reads Options for crontab use crontab option s 0 e to edit the file to list the contents of the file 0 u username use the u with a username argument to work with another users crontab file When using crontab e you have a number of fields 6 what they mean is listed below Allowed Values minute 0 59 hour 0 23 day of month month 1 12 or names see below day of week 0 7 0 or 7 1s Sun or use three letter names There are also a number of shortcut methods for common tasks including 9 Q reboot run command at reboot G yearly same as 00 1 1 C annually same as G yearly Q monthly same as 00 1 Q weekly same as 0 0 0 9 G daily same as 0 0 GC midnight same as Q daily G hourly same as 0 uo Note that asterisk is used to mean anything similar to the wildcard For example if you leave the
51. dcards Type Is d to list all subdirectories of the current directory Depending on the setup of your aliases see Chapter 4 you may simply be able to type sd as the equivalent to ls d Examples for s d lg d Lists all subdirectories of current directory m o Gl EI 3G Lists directories that start with string mm o cl AUS OP AM AGIS Lists all directories that are two levels below the usr directory and have a directory called doc this trick can come in quite handy sometimes i You can also use Depending on how your aliases see Chapter 4 are setup you can also use J a list all and list long to perform the above commands Print working directory Print the absolute complete path to the directory the user is currently in Command syntax pwd This will tell you the full path to the directory you are in for example it may output usr local bin if you are currently in that directory Outputs an ASCII text tree graph starting at a given directory by default the current directory This command recursively lists all files and all directories In other words it will list files within the directories below the current one as well as all files in the current directory tree has a large number of options refer to the manual page for details Command syntax pial eS S9 T Chapter 7 Working with the file system 22 GNU Linux Command Line Tools Summary tree
52. dd user to the end of the options list for the particular partition s mount Mount a device Attach the device to the file system hierarchy the tree This needs to be done so you can access the drive see below Section 9 1 for an example umount Unmount a device The command umount no n unmount s a device It removes it from the file system hierarchy the tree This needs to be done before you remove a floppy CDROM or any other removable device see below Section 9 1 for an example smbmount wincomp c mnt win Where win would be the place you want it mounted and wincomp is the IP address or name of your windows computer Please note Using ping smbmount ssh or other UNIX system programs with a computer name Chapter 9 Controlling the system 37 GNU Linux Command Line Tools Summary rather than IP address will only work if you have the computer listed in your etc hosts file Here is an example 192 ALG 1L MOO imexy This line says that their is a computer called new with IP address 192 168 1 100 Now that it exists in the etc hosts file I don t have to type the IP address anymore just the name new smbmount is a tool from the samba package it can mount a remote windows file system onto your current computer Un mounting uses the same syntax as umount as listed above or you may like to use smbumount mountpoint Here are some more examples of how to mount a file system mou
53. designate some or all of these sections as invariant To do this add their titles to the list of Invariant Sections in the Modified Version s license notice These titles must be distinct from any other section titles Appendix A Appendix 92 GNU Linux Command Line Tools Summary You may add a section entitled Endorsements provided it contains nothing but endorsements of your Modified Version by various parties for example statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard You may add a passage of up to five words as a Front Cover Text and a passage of up to 25 words as a Back Cover Text to the end of the list of Cover Texts in the Modified Version Only one passage of Front Cover Text and one of Back Cover Text may be added by or through arrangements made by any one entity If the Document already includes a cover text for the same cover previously added by you or by arrangement made by the same entity you are acting on behalf of you may not add another but you may replace the old one on explicit permission from the previous publisher that added the old one The author s and publisher s of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version A 3 6 COMBINING DOCUMENTS You may combine the Document with other documents released under this License under t
54. e Er roncos se LILA esac fromdos can be obtained from the from to dos website unix2dos This converts UNIX system style end of line characters to Microsoft style end of line characters Simply type unix2dos file txt This does the same as unix2dos above todos Simply type todos file txt todos can be obtained from the from to dos website antiword This filter converts Microsoft word documents into plain ASCII text documents Simply type antiword file doc You can get antiword from the antiword homepage recode Converts text files between various formats including HTML and dozens of different forms of text encodings Use recode 1 for a full listing It can also be used to convert text to and from Windows and UNIX system formats so you don t get the weird symbols Chapter 11 Text Related Tools 55 GNU Linux Command Line Tools Summary d Warning By default recode overwrites the input file use lt to use recode as a filter only and to not overwrite the file Examples UNIX system text to Windows text recode pc file name Windows text to UNIX system text recode pc file name UNIX system text to Windows text without overwriting the original file and creating a new output file recode pc file name gt recoded fil Windows to UNIX system style conversion only While tr is not specifically designed to convert files from Windows format to UNIX system format by doin
55. e a file directory Rename example mv filenamel filename2 Renames filenamel to filename2 To move a file or directory simply type mv original file or folder new location Note that this command can use standard wildcards Section 20 4 1 to move files not for renaming i Move and rename Chapter 7 Working with the file system 25 cp In GNU Linux Command Line Tools Summary Note that you can also move and rename a file in a single command The difference is with the destination right hand side you change the filename to the new name of the file For example typing mv etc configuration txt home joe backupconfig This would move the file configuration txt to home joe and rename it backupconfig Copy a file Has a number of useful options such as R or r which recursively copies directories and subdirectories Command syntax CPE OP EONS ile Or deles mew leesE gium Examples cp filel file2 Simply copy filel to file2 in the same directory cp tmp filel file2 mnt win c Where the last option is the directory to be copied to The above example copies two files from different areas of the file system to mnt win c cp R directory and or files new location This command will copy directories and all subdirectories and or files to new location Note that this command can use standard wildcards Section 20 4 1 to copy multiple files You may also like to try the u wh
56. e dore e d ERE Do eats 13 4 4 Virtual Terminals and screen esses hheh eese ennnenh teet eet sess sana setis etes esae 13 Chapter S Help csssssdscsessiisevssedestscesdsessosteessesesesdesvanyssenssesedssionssundsepaensdescenbdes soned suse PEERS eee Pe gei ca Toa Ere PE Y EP e ee esee 15 Chapter 6 Directing Input Output 5o reor eee eon ina eben no rote eon Ce boa e ne voa Tesi t Korn osea neon a Rer an a sonseseoseseseessones 17 6 1 Concept D finitions eoe e bad wos dete repere ER ERR TREO ERAN NEAR Gee OPE e ov suse 17 6 2 U Sape eere Ree On UY e aede ord sok eee He RE ER EL PNE EN onan oe eva alee 17 6 3 Command SubSUCt tiOD 1 eire torret beste ri ape Lot eet tb aee eL boe eoo e Dbeee o Do cos e bordes pa ee e eee 19 6 4 Performing more than one command sess enne enhn 19 Chapter 7 Working with the file systetm 4 ee ee eee eee e eee ee ee een eee to seen aeta aset ease sense tese se eae seen aee sa ee 21 7 1 Moving around the filesystem ccceecccesscecsseceseceeseeceececeeeeecaeeesaeceeaaeceaeeceeeeeseeeeeaaeceeaaeneaeeeeeeeees 21 PVs Pani TIES Ff eerte esee tete e re E eg Per en ce te Ped ee T ETRAS 23 7 2 Working with files and folders ette pr PRSE RR COH ETHER etae 24 7 3 Mass Rename copy Iimk Tools rere ee eene entente ee reae aero a eoe Eee du ate eaa gn 29 Chapter 8 Finding information about
57. e that should DNS not be configured correctly on your machine you need to edit etc resolv conf to make things work host dig whois Performs a simple lookup of an internet address using the Domain Name System DNS Simply type host ip_address S9 T host domain name The domain information groper tool More advanced then host If you give a hostname as an argument to output information about that host including it s IP address hostname and various other information For example to look up information about www amazon com type dig www amazon com To find the host name for a given IP address ie a reverse lookup use dig with the x option ghig lt 1 00542 30495 This will look up the address which may or may not exist and returns the address of the host for example if that was the address of http slashdot org then it would return http slashdot org dig takes a huge number of options at the point of being too many refer to the manual page for more information now BW whois is used to look up the contact information from the whois databases the servers are only likely to hold major sites Note that contact information is likely to be hidden or restricted as it is often abused by crackers and others looking for a way to cause malicious damage to Chapter 13 Network Commands 62 wget curl GNU Linux Command Line Tools Summary organisation s GNU Web get used to download
58. either commercially or noncommercially Secondarily this License preserves for the author and publisher a way to get credit for their work while not being considered responsible for modifications made by others This License is a kind of copyleft which means that derivative works of the document must themselves be free in the same sense It complements the GNU General Public License which is a copyleft license designed for free software We have designed this License in order to use it for manuals for free software because free software needs free documentation a free program should come with manuals providing the same freedoms that the software does But this License is not limited to software manuals it can be used for any textual work regardless of subject matter or whether it is published as a printed book We recommend this License principally for works whose purpose is instruction or reference A 3 2 APPLICABILITY AND DEFINITIONS This License applies to any manual or other work that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License The Document below refers to any such manual or work Any member of the public is a licensee and is addressed as you A Modified Version of the Document means any work containing the Document or a portion of it either copied verbatim or with modifications and or translated into another language A Secondary Section is a named ap
59. en file often with a asc extention to check whether the various files are correct this comes in handy when downloading isos as the checking is automated for you Command syntax md5sum file name mkpasswd 1 10 This command will make a random password of length ten characters This password generator creates passwords that are designed to be hard to guess There are similar alternatives to this program scattered around the internet 14 2 File Permissions Use Is 1 to see the permissions of files list long They will appear like this note that I have added spaces between permissions to make it easier to read Where r read w write x execute c WDR JE i gb 1 newuser newuser type owner group othersO o This number is the number of hard links pointers to this file You can use n to create another e hard link to the file This is the type of file means a regular file d would mean a directory l would mean a link There are also other types such as c for character device and b for block device found in the dev directory e o These are the permissions for the owner of the file the user who created the file These are the permissions for the group any users who belong is the same group as the user who created the file will have these permissions e These are the permissions for everyone else Any user who is outside the group will have these permissions to the file The two names at the end
60. en moving large directories around this copies only if the source file is newer than the destination to where you are copying to or if the destination file does not exist at all Create a link to a file There are two types of links Hard links Hard links are considered pointers to a file the number is listed by typing s Each hard link is a reference to a file The file itself only goes away when all hard links are deleted If you delete the original file and there are hard links to it the original file will remain Example ln target name link name Will create a hard link to target name called link name you need to delete both of these to remove the file Symbolic links Chapter 7 Working with the file system 26 GNU Linux Command Line Tools Summary Symbolic links are created by typing In s When you remove the original file the symbolic link becomes broken a symbolic link is similar to a windows short cut The advantage of symbolic links is that the target can be to something on another file system while hard links can only exist on the same file system For example ln s target name link name This creates a symbolic link to target name called link name if you delete the original file the symbolic link won t work it becomes a broken link shred Securely remove a file by overwriting it first Prevents the data from being recovered by software and even by most hardware please be very
61. er reading The most obvious place to look for documentation is to find the homepage of the program Although sometimes there are other sources of information such as the Linux Documentation Project or various online HOWTO s or similar guides They are usually easily found using search engines Try large sites such as biblio the publics library and digital archive or TuxFinder which can search for documentation Below is a very short list of some further reading for a few of the more complex tools OpenSSH OpenSSH manual page e vim The Vim HOWTO e emacs The Emacs HOWTO RPM RPM HOWTO e Samba Samba documentation site e ImageMagick ImageMagick command line tools e BASH BASH reference manual e Bash scripting Advanced bash scripting guide rsync rsync homepage Appendix A Appendix 88 GNU Linux Command Line Tools Summary A 2 2 1 The UNIX tools philosophy further reading e An article within the coreutils documentation installed on nearly every GNU Linux distro provides further explanation of the UNIX tools philosophy To access the article simply type Then type slash runs a search then the string toolbox toolbox is the string to be searched for then hit enter follow hyperlink and then go down to the Toolbox introduction section and hit enter This will give you access to the article e Other articles online include an Orielly article on the UNIX tools philosophy A listing of important qualities of the ph
62. es will be copied to the root directory of the remote computer called new which is probably on the LAN scp new Chapter 13 Network Commands 64 sftp GNU Linux Command Line Tools Summary You could also copy files from another computer to another computer Let s say you are on a computer called p100 And you want to copy files and directories from hp166 in the tmp directory and anything below that to new and put the files in new s temporary directory You could do scp r hpl66 tmp new tmp Assuming you were logged in as fred you would need passwords for user fred on the computers hp166 and new Add an user name before the computer name to login under a different user name For example to perform the above command with user root on hp166 and anon on new you would type scp r root hp166 tmp anonGnew tmp To copy from a remote machine to a local computer you simply do things in reverse scp remoteMachine mystuff This will copy files on the remote machine in the directory mystuff to your local computer Remote Machines Please note that when working with a remote machine you need to have a colon after the machine name even if you want the files in their home directory Otherwise the command will fail Secure ftp another part of the ssh package This command is similar to ftp but uses an encrypted tunnel to connect to an ftp server and is therefore more secure than just plai
63. everyone else other chmod 521 somefile This would give the user read and execute permission and the group write permission but not read permission and everyone else execute permission Note that it s just an example settings like that don t really make sense Changes the ownership rights of a file hence the name chown change owner This program can only be used by root Use the R option to change things recursively in other words all matching files including those in subdirectories Command syntax chown owner group the file name Chapter 14 Security 68 GNU Linux Command Line Tools Summary sticky bit suid chattr Only the person who created the file within a directory may delete it even if other people have write permission You can turn it on by typing chmod 1700 somedirectory where 1 sticky bit or where f represents the sticky bit chmod t somedirectory To turn it off you would need to type chmod 0700 somefile where the zero would mean no sticky bit or where f represents the sticky bit chmod t somefile Note that the permissions aren t relevant in the numbers example only the first number 1 on 0 off An example of a sticky directory is usually tmp Allow SUID SGID switch user ID switch group ID access You would normally use chmod to turn this on or off for a particular file suid is generally considered a security hazard so be careful when usin
64. fconfig eth0 down This will take ethO assuming the device exists down it won t be able to receive or send anything until you put the device back up again Clearly there are a lot more options for this tool you will need to read the manual info page to learn more about them Use ifup device name to bring an interface up by following a script which will contain your default networking settings Simply type ifup and you will get help on using the script For example typing ifup eth0 Will bring ethO up if it is currently down Use ifdown device name to bring an interface down using a script which will contain your default network settings Simply type ifdown and you will get help on using the script For example typing Chapter 13 Network Commands 61 ifcfg route GNU Linux Command Line Tools Summary ifdown eth0 Will bring ethO down if it is currently up Use ifcfg to configure a particular interface Simply type ifcfg to get help on using this script For example to change ethO from 192 168 0 1 to 192 168 0 2 you could do ECE Cra clei J92 169 09 1 Ireig Sila acli 192 168 052 The first command takes ethO down and removes that stored IP address and the second one brings it back up with the new address The route command is the tool used to display or modify the routing table To add a gateway as the default you would type route add default gw some computer 13 2 Internet Specific Commands Not
65. file fileaa 1st part of file fileab 2nd part of file fileac 3rd part of file etc until the there is no more of the file left to split 7 3 Mass Rename copy link Tools There are a few different ways to perform mass renaming of files in GNU Linux yes mass renaming is possible There is also a perl script that renames the extentions on files see Chapter 19 Chapter 7 Working with the file system 29 GNU Linux Command Line Tools Summary Below are three ways to perform mass renaming of files using the commands mmv rename a perl script or some bash shell scripting mmv mmv is a mass move copy renaming tool that uses standard wildcards to perform its functions mmv s manual page is quite difficult to understand I have only a limited understanding of this tool However mmv supports some standard wildcards According to the manual the wildcard is useful for matching files at any depth in the directory tree ie it will go below the current directory recursively An example of how to use mmv is shown below The first pattern matches anything with a JPG and renames each file the 1 matches the first wildcard to jpg Each time you use a wildcard you can use a x to get that wildcard Where x is a positive number starting at 1 i mmv Homepage You can find mmv on the web here Also be aware that certain options used with mmv are also applicable to other tools in the suite these include mcp mass copy mad
66. files from the World Wide Web To archive a single web site use the m or mirror mirror option Use the nc no clobber option to stop wget from overwriting a file if you already have it Use the c or continue option to continue a file that was unfinished by wget or another program Simple usage example wget url for file This would simply get a file from a site wget can also retrieve multiple files using standard wildcards the same as the type used in bash like Simply use wget as per normal but use single quotation marks on the URL to prevent bash from expanding the wildcards There are complications if you are retrieving from a http site see below Advanced usage example used from wget manual page wget spider force html i bookmarks html This will parse the file bookmarks html and check that all the links exist Advanced usage this is how you can download multiple files using http using a wildcard Notes http doesn t support downloading using standard wildcards ftp does so you may use wildcards with ftp and it will work fine A work around for this http limitation is shown below wget r LI no parent A gif http www website com 6 This will download recursively to a depth of one in other words in the current directory and not below that This command will ignore references to the parent directory and downloads anything that ends in gif If you wanted to
67. g ie eg Ne lt imputa tzt gt qguu cppuurie s e exe The d switch means to simply delete any occurances of the string Since we are looking for r carriage returns it will remove any it finds making the file a UNIX system text file You can read more about fr over here Section 11 4 11 5 1 Conversion tools enscript figlet Converts text files to postscript rtf HTML use ghostview to view the postscript file enscript has a large number of options which can be used to customise the output Examples 5 This will take some file and output it as a html file enscript help highlight Display help on using the highlight feature list all different types of highlighting available enscript help highlight Highlight pretty print example E color language html TOG output roor Incl lo eC Add all the files with a h and a c C source and header files into a file called foo html use colour and add a table of contents For further options refer to the well written manual page of enscript Chapter 11 Text Related Tools 56 GNU Linux Command Line Tools Summary Used to create ASCII art Figlet can create several different forms fonts of ASCII art its one of the more unusual programs around 11 6 Finding Text Within Files grep rgrep fgrep Looks for text within files For example grep this word this file txt Example options 9 v this option is used
68. g jobs to the foreground by name or by number use jobs to find the number Command syntax fg job number 9 T fg job name Sets the priority for a process nice 20 is the maximum priority only administrative users can assign negative priorities nice 20 is the minimum priority You must be root to give a process a higher priority but you can always lower the priority of your own processes nice 20 make Would execute make and it would run at maximum priority fes B 5 Changes the priority of an existing command You may use the options u to change the priorities of all processes for a particular user name and g to change priorities for all processes of a particular group The default is to change via the process id number renice 20 2222 This would change the priority of process 2222 to 20 minimum priority fes Pal B 5 snice works very similarly to skill only it changes the priority of the process es Its function is similar to that of renice To use options to ensure correct interpretation you simply type snice option s 0 u specify a username this is obviously followed by the user name or a space seperated list of usernames 9 p process id followed by the process id 9 c command name this is the same as killall 9 t tty number 9 v verbose mode 9 i interactive mode Chapter 9 Controlling the system 43
69. g this 6 1 Concept Definitions All three of the following definitions are called File Streams They hold information that is either received from somewhere or sent to somewhere In a UNIX system the keyboard input standard input information printed to the screen standard output and error output also printed to the screen are treated as separate File Streams Standard output Standard output is the output from the program printed to the screen not including error output see below Standard input Standard input is the input from the user Normally the keyboard is used as the standard input device in a UNIX system Standard error Standard error is error output from programs This output is also sent to the screen and will normally be seen mixed in with standard output The difference between standard output and standard error is that standard error is unbuffered it appears immediately on the screen and standard error is only printed when something goes wrong it will give you details of what went wrong 6 2 Usage gt The greater than symbol is used to send information somewhere for example a text file Example Cat sede sesh S gt minke anrd SEXE This will concatenate the files together into one big file named filel and 2 txt Note that this will overwrite any existing file The less than symbol will insert information from somewhere a text file as if you typed it yourself Often used with commands that are
70. g this Example chmod u s file name This will give everyone permission to execute the file with the permissions of the user who set the s switch d Security Hazard This is obviously a security hazard You should avoid using the suid flag unless necessary Change file system attributes works on ext2fs and possibly others Use the R option to change files recursively chattr has a large number of attributes which can be set on a file read the manual page for further information Example Glace da sloiim Lilo coms 7 This sets the immutable flag on a file Use a to add attributes and a to take them away The i will prevent any changes accidental or otherwise to the lilo conf file If you wish to modify the lilo conf file you will need to unset the immutable flag chattr i Note some flags can only be used by root i a and probably many others Note there are many different attributes that chattr can change here are a few more which may be useful Chapter 14 Security 69 GNU Linux Command Line Tools Summary 0 A no Access time if a file or directory has this attribute set whenever it is accessed either for reading of for writing it s last access time will not be updated This can be useful for example on files or directories which are very often accessed for reading especially since this parameter is the only one which changes on an inode when it s opened a append only
71. g trouble with a particular command try using a search engine such as Google or AllTheWeb or search the usenet groups Google Groups If you still can t find a solution look for a mailing list which is related to the topic you are having trouble with or try a forum which is related to the topic Readers who would like another reference to commands may want to have at e Commands from Linux in a Nutshell 3rd Edition as published by Orielly this document was not used in the creation of this guide however it is a comprehensive guide to GNU Linux Commands it s an indexed listing It lists and explains 379 commands taken from Linux in a Nutshell 3rd Edition e The Linux Newbie Admin guide list of commands another list of commands from an excellent system administration guide for GNU Linux e Comptechdoc s Linux Command Quickreference Guide a good list of commands but only one line explanations of what they actually do e SS64 com list of bash commands this page lists commands and links to their man pages online If you wish to learn more about GNU Linux on a variety of subjects also see the various online free tutorials published by IBM Developerworks If you are looking for a general reference to everything GNU Linux try the Rute User s Tutorial and Exposition Or take a look at your distributions documentation Debian maintains comprehensive documentation debian documentation site A 2 2 Specific Furth
72. ge other users passwords Simply type passwd to change your own password or to change another users password type passwd username Chapter 10 Managing users 46 Chapter 11 Text Related Tools The text related tools chapter is the largest in this guide most of the time on a GNU Linux machine you will spend time interacting with text This chapter briefly covers text editors and goes into more depth on viewing text using tools to manipulate text finding text within files and changing text formats between windows based systems and GNU Linux based systems 11 1 Text Editors vi emacs Others A traditional UNIX system text editor should be on any UNIX system It requires learning a few key combinations but is very powerful and it is also quite small vi is well known for its minimal use of resources S vim vim vi improved A newer version of the vulnerable vi editor Many systems use vim rather than vi More than just a text editor This text editor has a steep learning curve but is also very powerful it is both advanced and quite large emacs can do anything surf the internet chat play games and many other tasks There are too many different text editors to list here Have a look on the internet either search for them using any search engine or you will find many of them at Sourceforge or Freshmeat 11 2 Text Viewing Tools head tail With no options it shows the first ten lines of a text file
73. gistered trademark of The Open Group 2 2 License Copyright 2003 2006 Gareth Anderson Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 1 or any later version published by the Free Software Foundation with no Invariant Sections with no Front Cover Texts and with no Back Cover Texts A copy of the license can be found in the section called the GNU Free Documentation License or at the GNU Documentation License Site Chapter 2 Legal Chapter 3 The Unix Tools Philosophy A tool is a simple program usually designed for a specific purpose it is sometimes referred to at least throughout this document as a command The Unix tools philosophy emerged during the creation of the UNIX operating system after the breakthrough invention of the pipe l refer to Chapter 6 for information on using the pipe The pipe allowed the output of one program to be sent to the input of another The tools philosophy was to have small programs to accomplish a particular task instead of trying to develop large monolithic programs to do a large number of tasks To accomplish more complex tasks tools would simply be connected together using pipes All the core UNIX system tools were designed so that they could operate together The original text based editors and even TeX and LaTeX use ASCII the American text encoding standard an open standard and you can use to
74. h to file You may also like to try if it s installed it s generally a lot faster than the dpkg search dlocat S Pile sain For more information on dpkg and dlocate please refer to the relevant manual pages and online sources of information A 1 3 Finding package s Packages can be found via the internet utilizing sites such as e RPMFind for RPM based packages Debian Package Listfor deb packages e RPMSeek this site intends to index Debian packages as well as RPM e TuxFinder where you can search for deb rpm tgz iso and even documentation Also try the author s homepage and large sites such as FreshMeat and SourceForge A 2 Further Reading A 2 1 General Further Reading This guide is simply a short summary of some of the available tools of a GNU Linux based distribution If you find a particular command interesting and useful you can look up the on line manual or and info page to learn more about how to use this command or check the HOWTO s online at Linux Documentation Project Appendix A Appendix 87 GNU Linux Command Line Tools Summary The manual info pages will always be an up to date source of information on how to use the command Also have a look at the documentation installed on your distribution its normally located in usr share doc Check the references section of this document Bibliography for some links to useful resources which were used in the creation of this document Of course if you are havin
75. he following keys have been given special meaning in this document v Chapter 1 Introduction 3 GNU Linux Command Line Tools Summary Previous page N Next page H Home of the document Table of Contents U Up takes you one level up the section hierarchy If you also happen to be reading the document from its original location then the following access keys can also be used S Start takes you to the author s start page T The current This page without the Sitemenu on the left M The current page in a frameset where the left frame contains a Menu To use the access keys you have to simultaneously press a modifier key which may vary from browser to browser For example in NN6 Mozilla the modifier key is ALT so you have to use ALT N to go to the next page and ALT P to come back In other browsers such as IE6 the access keys just give focus to the associated link so the sequence becomes ALT N Enter Try it you ll like it Inline graphic 1 5 Resources used to create this document To create the GNU Linux Command Line Tools Summary I used LyX the document processor To convert the LyX files to DocBook SGML I used the lyxtox Scripts created by Chris Karakas You may also want to check out the db2lyx package created by Dr B Guillion which can be used to convert LyX files to XML DocBook and XML DocBook back to LyX I also had assistance from various The Linux Documentation Project volunteers see the
76. he terms defined in section 4 above for modified versions provided that you include in the combination all of the Invariant Sections of all of the original documents unmodified and list them all as Invariant Sections of your combined work in its license notice The combined work need only contain one copy of this License and multiple identical Invariant Sections may be replaced with a single copy If there are multiple Invariant Sections with the same name but different contents make the title of each such section unique by adding at the end of it in parentheses the name of the original author or publisher of that section if known or else a unique number Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work In the combination you must combine any sections entitled History in the various original documents forming one section entitled History likewise combine any sections entitled Acknowledgements and any sections entitled Dedications You must delete all sections entitled Endorsements A 3 7 COLLECTIONS OF DOCUMENTS You may make a collection consisting of the Document and other documents released under this License and replace the individual copies of this License in the various documents with a single copy that is included in the collection provided that you follow the rules of this License for verbatim copying of each of the documents in all other respect
77. htm html htm You can get a copy of the chcase perl script here For more complex renaming you should read Section 7 3 rel 11 Use rel to analyze text files for relevance to a given set of keywords It outputs the names of those files that are relevant to the given keywords ranked in order of relevance if a file does not meet the criteria it is not outputted in the relevance listing units man page There is a man page part of the Linux Programmers Manual called units It displays various information on the various scientific measurements such as mega giga et cetera This manual page also has a short discussion about the argument over which standard should be used to measure data ie the kibibyte vs kilobyte To access this man page type man 7 units fortune fortune is a tool which will print a random hopefully interesting quote or entertaining short piece of writing There are options to customise which area the epigrams should come from Just type fortune to get a random epigram from any section Simply type fortune Chapter 19 Miscellaneous 80 Chapter 20 Mini Guides The mini guides chapter is a section of the document that describes certain concepts in more depth than the usual command descriptions The information listed is fairly specific as I have tried to avoid the duplication of too much information that is already online 20 1 RPM Redhat Package Management System Checking Installed RPM
78. iddle it would look for an uppercase letter or a digit because it would become upper case letter any digit Chapter 20 Mini Guides 85 Appendix A Appendix A 1 Finding Packages Tools A 1 1 Finding more useful tools If you are looking to find more tools the GNU project GNU s Not Unix maintains a directory a website listing categorized links to various free software tools which they consider useful called the GNU Directory Also try sites such as Sweet Code which offer mailing lists of useful tools which they find You may also try looking at the most highly rated most active or most downloaded programs at SourceForge and FreshMeat A 1 2 Finding a particular tool s Many of the tools listed in this guide are part of a package of tools such as diffutils which contains the various tools used to find differences between files such as diff sdiff diff3 cmp Most small tools are bundled together in this fashion Most major distribution s will offer a search function to help you search the packages by file you can of course do this via the command line interface or a GUI If you need to search the distribution s available packages via the command line the method will vary depending on the distribution you are using see the subsections below or consult your distribution s documentation or of course the internet A 1 2 1 Mandriva urpm commands rpm based To find where a particular file came from use urpmf Comma
79. igned to do different things try searching for them on the internet or within your distribution Chapter 11 Text Related Tools 57 Chapter 12 Mathematical tools num utils homepage The num utils homepage Num Utils contains a variety of command line programs that could be useful when performing maths on your GNU Linux machine units python Convert units of measurement between different scales For example centimeters to inches litres to gallons Simply run the program I recommend running it as follows units verbose This will run the program and it will tell you exactly what it is doing Example you enter 60 meters then you want it worked out in kilometers The first line will tell you what this evaluates to If you wanted the conversion rate for meters to kilometers read the second line of the output which will tell you meters 1000 cg To exit Press CTRL D end of file key when you are finished using units Python is a very powerful easy to learn general purpose interpreted programming language And it makes a great calculator If you don t have a calculator installed then simply type python then hit Enter This will execute the Python interpreter in interactive mode Type your sums just like you would use a calculator Note that if you want to work out fractions make sure you use a decimal point and a zero to obtain the correct answer otherwise it will use integer division To st
80. ii ertet erret cutee ente hehe e Ree Rt Tea ere ete e Re dene 86 A 1 1 Finding more useful tools sessi enne eterne nns 86 A 1 2 Finding a particular toOl S cccescccesccessecesscecseccensneecesccesaecseaeecseaecseneecueeesaecseaaeceaaeseeneeeues 86 Ash 3 Findinpe package s sees er ertet etre ride nae be ee Ee pe ee ads 87 A2 Further Reading 5 eene ettet T E ee eee ee ore Eee ete eq a 87 GNU Linux Command Line Tools Summary Table of Contents Appendix A Appendix A21 General Further Reading ette rebote EESE E Nt 87 A22 Specific F rther readmo i ii e ie esie t caves EE ES REPRE ERE Ee e ege Db a 88 A 2 3 Online Manual And Info Pag s sirenenet eneinio 80 A 3 GNU Free Documentation License eeeeeeeeeeeeeeeeeeneee enne ee emen en en eene enini nene ne nnne nnn 89 AGO PREAMBEE ii sedaiuse nete RR ROE OEE IRE 90 A 3 2 APPLICABILITY AND DEFINITIONS eere nnne 90 A 3 3 VERBA TINMECOP YENGI s bouton cresce detener tede eae ee de xen ee e var beu Ep EY ETT e 91 A 3 4 COPYING IN QUANTITY eni tete te eot tete ves ei EGER EP REA a de edere etian 91 A335 MODIEICAFIONS 5 crees esee eene eerte es eee re e re eeu pn RAPERE NEA aee ege Sa TOON Y A oit 91 A 3 6 COMBINING DOCUMENT ccccccccccsesesssssssssesssecccececscesccscsceseececseseeeeessceseeeeeeaes 93 A 3 7 COLLECTIONS OF DOCUMENTS sees enn nnn nnn nn nn nn aoina n konoan 93
81. ilosophy e Linux Exposed The Unix Philosophy Explained Oran entire book which is considered the authoritative guide toward understanding the philosophy behind how the UNIX system was built The book is called The Unix Philosophy ISBN 1555581234 A 2 3 Online Manual And Info Pages While manual pages and info pages are usually installed with the program itself they are also available online if you need them the listed links are usually listed by category or by the man page sections A 2 3 1 Online Manual Page Websites Manual Page Resource Links from the Linux Documentation Project A RedHat Based Searchable Index Another Searchable Index Another Manual Page Site searchable A 2 3 2 Downloadable Manual Pages Downloadable Man Pages hosted by Ibiblio A 2 3 3 Online Info Page Website e GNU Manual s A 3 GNU Free Documentation License GNU Free Documentation License Version 1 1 March 2000 Copyright C 2000 Free Software Foundation Inc 59 Temple Place Suite 330 Boston MA 02111 1307 USA Everyone is permitted to copy and distribute verbatim copies of this license document but changing it is not allowed Appendix A Appendix 89 GNU Linux Command Line Tools Summary A 3 1 PREAMBLE The purpose of this License is to make a manual textbook or other written document free in the sense of freedom to assure everyone the effective freedom to copy and redistribute it with or without modifying it
82. int the date 3 months and 1 day ago from the current date Note that date x month x day ago and d x month x day ago are equivalent darter d NGC The above command will print the date 3 days in the future from now Typing cal will give you the calendar of the present month on your screen in the nice standard calendar format There are various options to customise the calendar refer to the info man page Example Q e um y year Will display a calendar for a specific year simply use cal y to print the calendar for the current year cal 2 20904 Chapter 8 Finding information about the system 35 GNU Linux Command Line Tools Summary This will display the calendar for February 2004 8 2 Finding information about partitions There are a number of ways to find out information on your hard disk drives for information on mounted partitions also try dfin Chapter 8 Using the proc filesystem You can look through the information in the relevant area of the proc filesystem under the directory of either proc ide or proc ide hd where the first question mark is a number and the second is a letter starting with a For example cd proc ide0 hda Under this directory there will be various information on the hard drive or cdrom connected Using fdisk Using fdisk with the option will output information on any hard drives connected to the system and information on their partitions for example the ty
83. ion or of any later version that has been published not as a draft by the Free Software Foundation If the Document does not specify a version number of this License you may choose any version ever published not as a draft by the Free Software Foundation Bibliography 1 Tony Steidler Dennison Lockergnome Penguin Shell Series Lockergnome Responsible for many of the commands listed in this document In particular Lockergnome inspired much of the wildcards section Section 20 4 2 Brandon Rhodes Linux Network Commands Page Appendix A Appendix 94 GNU Linux Command Line Tools Summary Responsible for parts of the network commands section Chapter 13 3 Michael Stutz Linux Cookbook Homepage No Starch Press Many of these commands have come from the Linux Cookbook version 1 2 I highly recommend this book to any novice or intermediate GNU Linux user have a look at it online and then of course buy it 4 Michael Jordan Linux Online Classroom Linux Online Some very small sections of this document were taken from the Beginner s course on the Linux Online Website 5 man and info pages The man and info pages of various tools listed in this document have been used as a resource to assist in the creation of this document They are a useful resource of up to date information on a program and should be consulted when you require information about a particular tool 6 Focus On Unix Unix about com Some of the
84. is no using the above cd command Using a would cause this to be an absolute path working from the top of the hierarchy downward List files and directories Typing Is will list files and directories but will not list hidden files or on directories that start with a leading full stop Example options 0 Is l long style this lists permissions file size modification date ownership 0 ls a this means show all this shows hidden files by default any file or directory starting with a will not be shown 0 ls d list directory entires rather than contents see example below 0 Is F append symbols to particular files such as asterisk for executable files 0 s S sort the output of the command in decending order sorted by size 0 ls R recursive to list everything in the directories below as well as the current directory Chapter 7 Working with the file system 21 pwd tree GNU Linux Command Line Tools Summary Command syntax either ls options This simply lists everything in the current directory the options are not required options such as a et cetera lg epiuXoms Sti ig This lists files using a certain string The string can contain standard wildcards to list multiple files to learn more about standard wildcards please read Section 20 4 1 You can use s d to show directories that match an exact string or use standard wil
85. is the same as killall 9 t tty number 0 v verbose mode 9 i interactive mode skill can be used to stop continue or kill processes using the username command name or process id or send them any variety of signals you like Useful example Skill STOP abusive user name The above command will stop all of that users processes this will cause his screen to freeze until you type This would tell that all processes may continue as before Note that this would only work if you are root Also note you can list more than one user name with the command so it will apply to multiple users CTRL C The break key will kill break stop something that s running on your terminal jobs Prints currently running jobs as in processes you have executed within the shell bg Backgrounds a process To start a program in the background so it doesn t take over the terminal use an amp ampersand sign at the end of the command You usually use CTRL Z to suspend something Chapter 9 Controlling the system 42 fg nice renice snice GNU Linux Command Line Tools Summary you are currently using You can simply use bg to resume in the background the last job suspended Command syntax bg job number ie T bg job name Bring a process to the foreground so you can interact with it The process will use your current terminal Note simply use f2 to foreground the last job number suspended You can brin
86. istory list You can also type n to execute command number n Use to execute the last command you typed n will execute the command n times before in other words is equivalent to string will execute the last command starting with that string and string will execute the last command containing the word string For example Will re run the command that you last typed starting with cd commandName will execute the commandName with any arguments you used on your last command This maybe useful if you make a spelling mistake for example If you typed emasc home fred mywork java tmp testme java In an attempt to execute emacs on the above two files this will obviously fail So what you can do is type emacs This will execute emacs with the arguments that you last typed on the command line In other words this is equivalent to typing Searching through the Command History CTRL R Use the CTRL R key to perform a reverse i search For example if you wanted to use the command you used the last time you used snort you would type CTRL R then type snort Chapter 4 Shell Tips 12 GNU Linux Command Line Tools Summary What you will see in the console window is reverse i search After you have typed what you are looking for use the CTRL R key combination to scroll backward through the history Use CTRL R repeatedly to find every reference to the string you ve entered Once
87. ith a gz extension Gzip can compress any type of file it doesn t have to be a tar archive gunzip your file gz This will decompress a gzipped file and leave the contents in the current directory bzip2 bzip2 is a newer compression program taht offers superior compression to gzip at the cost of more processor time bzip2 your tar file tar This will compress a tar archive with the bzip2 compression program usually with a bz extension bzip2 can compress any type of file it doesn t have to be a tar archive bunzip2 your file tar bz2 This will decompress a file compressed by bzip2 and leave the contents in the current directory zipinfo Use zipinfo to find detailed information about a zip archive the ones usually generally used by ms dos and windows for example winzip Q o 8 5 e B a n B et e x gagstiauti zs 3eat IVS zatio zipgrep Will run grep to look for files within a zip file ms dos style for example winzip without manually decompressing the file first Command syntax Chapter 15 Archiving Files 72 GNU Linux Command Line Tools Summary zipgrep pattern zip file zip bzip2recover Used to recover files from a damaged bzip2 archive It simply extracts out all the working blocks as there own bzip2 archives you can than use bzip2 t on each file to test the integrity of them and extract the working files bzme Will convert a file that is zipped or gzipped to a file compressed using bzip2
88. k for hda hdb hdc and every other letter number between a z 0 9 asterisk this can represent any number of characters including zero in other words zero or more characters If you specified a cd it would use cda cdrom cdrecord and anything that starts with cd also including cd itself m could by mill mull ml and anything that starts with an m and ends with an 1 square brackets specifies a range If you did m a o u m it can become mam mum mom if you did m a d m it can become anything that starts and ends with m and has any character a to d inbetween For example these would work mam mbm mcm mdm This kind of wildcard specifies an or relationship you only need one to match curly brackets terms are separated by commas and each term must be the name of something or a wildcard This wildcard will copy anything that matches either wildcard s or exact name s an or relationship one or the other For example this would be valid C9 it seloc joche This will copy anything ending with doc or pdf to the users home directory Note that spaces are not allowed after the commas or anywhere else This construct is similar to the construct except rather than matching any characters inside the brackets it ll match any character as long as it is not listed between the and This is a logical NOT For example rm myfile 9 will remove all myfiles ie myfiles1 myfiles2 et
89. led but does so using regular expressions See below for more information For example kalel iy monilla Chapter 9 Controlling the system 41 GNU Linux Command Line Tools Summary Would kill anything named mozilla and prompt you before each kill and report whether the kill was successful or not Unfortunately you need to get the name exactly right for killall to work you would need to use mozilla bin to kill the mozilla browser If you want something where you don t need to know the exact name try pkill below pkill pkill is used to kill processes according to an extended regular expression Use the u option to kill using a user name s and process name for example to only kill a process of a certain user pkill can also send specific signals to processes For normal usage simply type Note that the process name doesn t have to be an exact match Or to kill the process name of only the users fred and anon type pkill u fred anon process name skill skill is used to send a command username tty a particular signal skill has a number of options available to ensure correct interpretation otherwise it just guesses what it is simply type skill option s 9 L list the various signals that can be sent 0 u specify a username this is obviously followed by the user name or a space seperated list of usernames 9 p process id followed by the process id 9 c command name this
90. lity of sources The modifiable sources of the original book in english are available in LyX format LyX Document Processor or Machine translated SGML SGML markup language LyX is a completely free document processor based on LaTeX downloadable from the LyX homepage See for the modifiable sources of this document These are the official versions We the translators and current maintainers plan to continue work on this document and add new chapters and enhancements If you want to see the version we are currently working on the bleeding edge version check the GNU Linux Command Line Tools Summary Homepage from time to time kindly hosted by Chris Karakas 1 4 Conventions used in this guide The following conventions are used within this guide italic Anything appearing in italic like this is either an executable command or emphasized text Tools executable commands are in italics to prevent confusion Some tools have names which are real english words such as the locate tool key combinations Are represented by using a dash sign in between the key s which must be used in combination All combinations are also printed in italics to improve clarity For example CTRL Z means hold down the Control key and press the z key admonitions Admonitions are little pictures used to emphasize something of importance to the reader Chapter 1 Introduction 2 GNU Linux Command Line Tools Summary The five types used are
91. ll also display various other things It has many different options tcpdump ping This is a sniffer a program that captures packets off a network interface and interprets them for you It understands all basic internet protocols and can be used to save entire packets for later inspection The ping command named after the sound of an active sonar system sends echo requests to the host you specify on the command line and lists the responses received their round trip time You simply use ping as ping ip or host name Note to stop ping otherwise it goes forever use CTRL C break 2 Please note Using ping smbmount ssh or other UNIX system programs with a computer name rather than IP address will only work if you have the computer listed in your etc hosts file Here is an example 192 4 11656 1k LOO mena This line says that their is a computer called new with IP address 192 168 1 100 Now that it exists in the etc hosts file I don t have to type the IP address anymore just the name new hostname Tells the user the host name of the computer they are logged into Note may be called host traceroute traceroute will show the route of a packet It attempts to list the series of hosts through which your packets travel on their way to a given destination Also have a look at xtraceroute one of several graphical equivalents of this program Command syntax traceroute machine_name_or_ip tracepath trace
92. ll files in the current directory and it will list the size of subdirectories it will list things in human readable sizes using 1024 Kb is a Megabyte M for megabyte K for kilobyte etc Attempts to find out what type of file it is for example it may say it s binary an image file well it will say jpeg bmp et cetera ASCII text C header file and many other kinds of files it s a very useful utility Command syntax file file name Tells you detailed information about a file including inode number creation access date Also has many advanced options and uses For simple use type Seat sea ks Copies data on a very low level and can be used to create copies of disks Section 20 3 and many other things for example CD image files dd can also perform conversions on files and vary the block size used when writing the file Command syntax note the block size and count are optional and you can use files instead of devices Please note dd is an advanced and difficult to use command Its also very powerful so be careful what you do with it Chapter 7 Working with the file system 28 GNU Linux Command Line Tools Summary Command syntax dd if dev xxx of dev xxx bs xxxx count x EJ Warning The command dd is used to work on a very low level It can be used to overwrite important information such as your master boot record or various important sections of your hard disk Please be careful when using it e
93. mands to run in the background There are two main tools used to perform scheduled tasks at and cron You may also like to try anacron if your computer does not run continuously as cron will only work if your computer is left on anacron can catch up with the scheduled tasks the next time the computer is on at atq atrm cron crontab at executes a command once on a particular day at a particular time af will add a particular command to be executed Examples eue Zils 30 You then type the commands you want executed then press the end of file key normally CTRL D Also try at now time This will run at the current time the hours mins seconds you specify use at now I hour to have command s run in 1 hour from now You can also use the f option to have at execute a particular file a shell script ais i ehall exei mow s dL Inoue This would run the shell script 1 hour from now Will list jobs currently in queue for the user who executed it if root executes at it will list all jobs in queue for the at daemon Doesn t need or take any options Will remove a job from the at queue Command syntax Will delete the job job no use atq to find out the number of the job cron can be used to schedule a particular function to occur every minute hour day week or month It s normal to use the crontab to perform the editing functions as this automates the process for the cron daemon an
94. mass append contents of source file to target name mln mass link to a source file i Tip A Java alternative to mmv which runs on both GNU Linux and Windows is available Esomaniac rename rename is a perl script which can be used to mass rename files according to a regular expression An example for renaming all JPG files to jpg is rename s N JPG jpg JPG Finding rename You can get rename from various places I would recommend trying CPAN Search Site I found the script here Rename Script Version 1 4 Bash scripting Bash scripting is one way to rename files You can develop a set of instructions a script to rename files Scripts are useful if you don t have mmv or rename One way to this is shown below POS al alin 7 9 WIGS do mv i basename i JPG jpg Chapter 7 Working with the file system 30 GNU Linux Command Line Tools Summary done Note that the above script came from a usenet post Unfortunately I do not know the author s name The first line says find everything with the JPG extension capitals only because the UNIX system is case sensitive The second line uses basename type man basename for more details with the i argument The i is a string containing the name of the file that matches The next portion of the line removes the JPG extension from the end and adds the jpg extention to each file The command mv is run on the output An alternative is POE ab alin 7 9 Sep
95. mat ie if there are 1024 kilobytes left approximately then df will say there is 1MB left Command syntax df options dev hdx The latter part is optional you can simply use df with or without options to list space on all file systems Displays information on which users are logged into the system including the time they logged in Command syntax who Chapter 8 Finding information about the system 32 GNU Linux Command Line Tools Summary Displays information on who is logged into the system and what they are doing ie the processes they are running It s similar to who but displays slightly different information Command syntax users Very similar to who except it only prints out the user names who are currently logged in Doesn t need or take any options Command syntax users last Displays records of when various users have logged in or out This includes information on when the computer was rebooted To execute this simply type last lastlog Displays a list of users and what day time they logged into the system Simply type whoami Tells the user who they are currently logged in as this is normally the usename they logged in with but can be changed with commands like su whoami does not need or take any options Simply type free Displays memory statistics total free used cached swap Use the t option to display totals of everything and use the m to display memory in megabytes Example Thi
96. mission from their copyright holders but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections You may include a translation of this License provided that you also include the original English version of this License In case of a disagreement between the translation and the original English version of this License the original English version will prevail A 3 10 TERMINATION You may not copy modify sublicense or distribute the Document except as expressly provided for under this License Any other attempt to copy modify sublicense or distribute the Document is void and will automatically terminate your rights under this License However parties who have received copies or rights from you under this License will not have their licenses terminated so long as such parties remain in full compliance A 3 11 FUTURE REVISIONS OF THIS LICENSE The Free Software Foundation may publish new revised versions of the GNU Free Documentation License from time to time Such new versions will be similar in spirit to the present version but may differ in detail to address new problems or concerns See Copyleft Each version of the License is given a distinguishing version number If the Document specifies that a particular numbered version of this License or any later version applies to it you have the option of following the terms and conditions either of that specified vers
97. n ftp The command usage is very similar to ftp the command line tool sftp once running uses commands such as help for help put send files to the server get download files from the server and various others refer to the manual page and internal documentation for further details i Graphical programs Sometimes its easier to manage files with a GUI many of these programs do have good GUI equivalents try searching the internet or sites like Sourceforge or Freshmeat Chapter 13 Network Commands 65 Chapter 14 Security The security chapter is designed to give the user a very basic level of understanding of security within the GNU Linux operating system This chapter also has information on the UNIX system style file permissions used on most GNU Linux machines More comprehensive guides can be found at the Linux Documentation Project such as the Linux Security howto authored by Kevin Fenzi and Dave Wreski There are also sites such as Linux Security If your looking for a program to assist in locking down your operating system you may want to check Bastille Linux that runs on RPM based distributions Redhat Mandriva SuSE Changing root s password umask This trick works well if you have forgotten your superuser password type linux single at a LILO Grub prompt Then passwd once the system has started and you are at a console Grub If you are using grub go to the relevant line the one with the kernel and various op
98. n the shopping list then sort the results and display them in alphabetical order BOWE Hie SMOAR Se exe The above command would run sort on a file and sort the file in reverse alphabetical order Advanced sort commands Chapter 11 Text Related Tools 50 join cut GNU Linux Command Line Tools Summary sort is a powerful utility here are some of the more hard to learn and lesser used commands Use the t option to use a particular symbol as the separator then use the k option to specify which column you would like to sort by where column 1 is the first column before the separator Also use the g option if numeric sorting is not working correctly without the g option sort just looks at the first digit of the number Here is a complex example Soc 8 k 4 k I sg cete gsseswe more This will sort the etc passwd file using the colon as the separator It will sort via the 4th column GID section in the file and then sort within that sort using the first name to resolve any ties The g is there so it sorts via full numbers otherwise it will have 4000 before 50 it will just look at the first digit Will put two lines together assuming they share at least one common value on the relevant line It won t print lines if they don t have a common value Command syntax join filel file2 Prints selected parts of lines of a text file or in other words removes certain sections of a line You may
99. nalias to remove the alias to disable it just for one command add a back slash before the command An alias allows one command to be substituted for another This is used to make a command do set x GNU Linux Command Line Tools Summary something else or to automatically add certain options This can be either be done during one session using the alias command see below or the information can be added to the bashrc file found in the users home directory Below is an example of what an alias section within your bashrc file might look like my personal aliases alias cp cp vi to prompt when copying if you want to overwrite and will tell you where alias rm rm i Prompts you if you really want to remove it alias mv mv i Prompts you if you are going to overwrite something On any Mandriva GNU Linux system the global aliases for all users are all in etc profile d alias sh The above listed commands already have aliases as well as several other commonly used commands set is one of bash s inbuilt commands try looking in the bash manual for its many usage options Using set with the x option will make bash print out each command it is going to run before it runs it This can be useful to find out what is happening with certain commands such as things being quoted that contain wildcards or special symbols that could cause problems or complex aliases Use set x to turn this back off Examples Af
100. nd syntax urpmf file name The results are often overwhelming as this particular command will take a string and list every file of every package in it s database that contains the particular keyword ie both uninstalled and installed packages To refine the results you may want to add a pipe to it and send it through grep w file name the w option will only show you only exact whole word matches How you would do this is shown below urpmf file name grep w file nam For more information on the urpm commands please refer to the tip towards the end of this section Section 20 1 A 1 2 2 Red Hat rpm To find which package a particular file came from use rpm with the qf option Command syntax Appendix A Appendix 86 GNU Linux Command Line Tools Summary ome Spe partha to thel iile This will find which package the file came from You need to use rpm qf not with a keyword but with the location of the actual file To find more information on the particular package listed use rpm with the qi option Command syntax rpm qi package name Note that the package name is the name of the package without the arch rpm often i386 rpm extension on the end For more information on the usage of rpm please refer to this section Section 20 1 A 1 2 3 Debian deb To find where a particular file came from use dpkg with the S option There are two ways to do this dpkg S file name dpkg S pat
101. ng a tool is this example cat ken snes exse Combines concatenates multiple documents into one document Can be used on individual files as well Some useful options b number all non blank lines 9 n number all lines Also try using nl to number lines it can do more complex numbering you will find it under under this section Section 11 4 fes E 5 e cat filepartl filepart2 filepart3 gt wholefile txt This will combine concatenate filepart1 filepart2 and filepart3 into the single file wholefile txt Combines concatenates multiple documents into one document and outputs them in reverse order Can also be used on individual files Notice that tac is cat written backwards Example tac filepartl filepart2 filepart3 gt wholefile txt This will combine concatenate filepart1 filepart2 and filepart3 into the single file but have each of the files written in reverse Z commands Many commands can be prefixed with a z to read work within a gzip compressed file Chapter 11 Text Related Tools 48 GNU Linux Command Line Tools Summary Some examples are zcat zless zmore zgrep zcmp zdiff There are many utilities for working with text within compressed files without trying to manually de compress them somewhere first most begin with a z You will find some of them mentioned over here Section 15 3 bz commands There are also a few commands that prefixed with a b
102. ng for many of the commands Chris is also responsible for the great looking HTML file for this document the CSS file and HTML customisations are completely his work Chris has also helped fix up problems in the document many times especially with docbook sgml and LyX related issues Chris has also improved the structure of the document by adding labels and fixing minor errors William West William provided a thorough review of the document as required by the Linux Documentation Project He is responsible for a variety of improvements to the quality of this document His contributions include 9 Improvements to the readability of this document 9 Improvements to the structure and consistency of this document Various grammar improvements throughout the document Repair of some minor technical errors Tabatha Persad Marshall Tabatha as the Linux Documentation Project Review Coordinator at the time also gave a brief review of this document Her general advice was used to improve the structure language and grammar of the document Rahul Sundaram Rahul provided a brief review of this document for the Linux Documentation Project Advice from his brief review was integrated into this document to improve readability and structure several references were added as recommended by Rahul David Lawyer David s criticism of the document via the TLDP discuss list were listened to and attempts to improve the document were made A
103. nt t ext2 dev fdO0 mnt floppy o mount t iso9660 dev hdb mnt cdrom mount t iso tmp image file mnt iso file o loop e The windows filesystem is known as vfat standard on Windows 9x or NFTS standard on Windows 2000 and XP for CDROM s This will mount an image file usually a CD image file so you can view change the files it will appear to be like any other device S The t option On any system running a newer version of the Linux kernel the t option is not always necessary and can be left out Examples of how to unmount a file system necessary before you eject remove disk umount mount point An example unmount point could be mnt floppy or mnt cdrom 9 2 Shutting Down Rebooting the System shutdown now Shutdown the computer immediately don t power down Note that in UNIX systems this kind of shutdown means to go to single user mode Single user mode is a mode where only the administrator root has access to the computer this mode is designed for maintenance and is often used for repairs For example this would take you to single user mode shutdown h now Shutdown h halt the computer immediately It begins the shutdown procedure press CTRL C break key to stop it After the end of the command you can also leave a message in quotation marks Chapter 9 Controlling the system 38 GNU Linux Command Line Tools Summary which will be broad casted to all users for example
104. ocal to remote and vice versa and to and from rsync servers rsync uses an advanced differencing algorithm so when to copies or syncs something it will a only copy new changed files and b if the files have being changed it will copy the differences between Chapter 15 Archiving Files 71 GNU Linux Command Line Tools Summary the files not the entire file Using this method rsync saves time and bandwidth rsync also has advanced exclusion options similar to GNU tar rsync has a well written manual page for further information read the rsync documentation online or type man rsync If you wish to visit the rsync site you will find it over here 15 3 Compression There are two main compression utilities used in GNU Linux It s normal to first tar a bunch of files using the tar program of course and then compress them with either bzip2 or gzip Of course either of these tools could be used without tar although they are not designed to work on more than one file they use the UNIX tools philosophy let tar group the files they will do the compression this simplifies their program It s normal to use far and then use these tools on them or use tar with the correct options to use these compression programs GNU zip gzip gzip is the GNU zip compression program and probably the most common compression format on UNIX like operating systems gzip your tar file tar This will compress a tar archive with GNU zip usually w
105. ols such as sed awk vi grep cat more tr and various other text based tools in conjunction with these editors Using this philosophy programmers avoided writing a program within their larger program that had already been written by someone else this could be considered a form of code recycling For example command line spell checkers are used by a number of different applications instead of having each application create its own own spell checker This philosophy lives on today in GNU Linux and various other UNIX system based operating systems FreeBSD NetBSD OpenBSD etc For further information articles on the UNIX tools philosophy please see the further reading section here Section A 2 2 1 Chapter 3 The Unix Tools Philosophy 8 Chapter 4 Shell Tips The shell tips chapter provides handy tricks that you may wish to use when you are using a GNU Linux shell the command line interface This information includes handy shortcut key combinations the shell s command history and information on virtual terminals If you can t boot into your system If your having problems booting into your system you may like to use a shell so you can boot into your system and attempt to fix things up again To do this you need to pass the init bin sh to your system before you boot up If you don t know how to do this please see Chapter 14 the technique is the same except this time you pass init bin sh rather than single 4 1
106. ories under mnt win c When using the path option you can use wildcards Note that you could add more path directory statements on if you wanted find has many many different options refer to the manual and info page for more details slocate slocate outputs a list of all files on the system that match the pattern giving their full path name it doesn t have to be an exact match anything which contains the word is shown Replaces locate Secure locate is a replacement for ocate both have identical syntax On most distributions locate is an alias to slocate Commmand syntax slocate string amp This won t work unless You need to run either updatedb as root or slocate u as root for slocate to work whereis whereis locates the binary source and manual page for a particular program it uses exact matches only if you only know part of the name use slocate Command syntax whereis program name which Virtually the same as whereis except it only finds the executable the physical program It only looks in the PATH environment variable of a users shell Use the a option to list all occurances of the particular program name in your path so if theres more than one you can see it Command syntax which program name 7 2 Working with files and folders mkdir Make a directory Use mkdir p to create subdirectories automatically Directories are Folders Chapter 7 Working wi
107. other xargs tutorial Alternatives to using xargs Please note that the below explanation of xargs is not the strongest at the time of writing I could not find anything better Alternatives may include writing a simple bash script to do the job which is not the most difficult task in the world Examples ls xargs grep work The first command is obvious it will list the files in the current directory For each line of output of Is xargs will run grep on that particular line and look for the string work The output have the each time grep is executed on a new line the output would look like file name results of grep If grep didn t find the word then there would be no output if it had an error then it will output the error Obviously this isn t very useful you could just do This is just a simple example xargs also takes various options 0 nx will group the first x commands together Ix xargs will execute the command for every x number of lines of input 9 p prompt whether or not to execute this particular string t tell be verbose echo each command before performing it 9 i will use substitution similar to find s exec option it will execute certain commands on something Example Chapter 8 Finding information about the system 34 GNU Linux Command Line Tools Summary ie hid saree al uy gr 4h ea The would be substituted for the current inp
108. p www site com 13 3 Remote Administration Related ssh scp Secure shell remotely login on a machine running the sshd daemon Once you are logged in you have a secure shell and are able to execute various commands on that computer such as copy files reboot the computer just like it was your own GNU Linux PC Or you can use ssh with a full hostname to connect to a remote machine as in across the internet ssh hostname Connect to a remote system with your current username you will obviously need the password of the user on the other machine x S 9 9 A ssh usernameGhostname Connect to a remote system with your a different username you will obviously need the password of the user on the other machine Secure copy part of the ssh package Allows you to copy files from one computer to another computer use r to copy recursively copy entire directories and subdirectories scp s syntax is always scp machineToBeCopiedFrom machineToBeCopiedTo Where either machine can be a local directory on the current filesystem or a remote machine Remote machines are usually machines FullName directory if you omit the directory part it will just assume the home directory of the username you are logging in with The example below copies all files from the current directory not including any directories the command will login to new using the username of the person currently logged in on the local computer the fil
109. path performs a very simlar function to traceroute the main difference is that tracepath doesn t take complicated options Command syntax tracepath machine_name_or_ip Chapter 13 Network Commands 60 GNU Linux Command Line Tools Summary findsmb nmap 13 1 findsmb is used to list info about machines that respond to SMB name queries for example windows based machines sharing their hard disk s Command syntax findsmb This would find all machines possible you may need to specify a particular subnet to query those machines only network exploration tool and security scanner nmap is a very advanced network tool used to query machines local or remote as to whether they are up and what ports are open on these machines A simple usage example nmap machine name This would query your own machine as to what ports it keeps open nmap is a very powerful tool documentation is available on the nmap site as well as the information in the manual page Network Configuration ifconfig ifup ifdown This command is used to configure network interfaces or to display their current configuration In addition to activating and deactivating interfaces with the up and down settings this command is necessary for setting an interface s address information if you don t have the ifcfg script Use ifconfig as either aL iE GO IMIE sug This will simply list all information on all network devices currently up i
110. pe of partition Information relating to using fdisk to partition hard disks can be found in your distributions documentation the fdisk manual page or online g Root Access Required This command needs root access to work Chapter 8 Finding information about the system 36 Chapter 9 Controlling the system The controlling the system chapter details commands that you may wish to use to interact with devices on your system and then details how to control processes and services daemons eject eject simply tells a device to open eject the drive Useful for cdrom D VD drives For example the command below would eject the cdrom drive if your cdrom is linked to dev cdrom eject dev cdrom This won t work unless This will only work if the user has permission to mount the partition Please see the tip in Section 9 1 for more information 9 1 Mounting and Unmounting Floppy CDROM Hard drive Partitions i Allowing Users to mount partitions By default a UNIX system will allow normal users to unmount partitions However unless given permission by the superuser users will not be allowed to mount partitions The commands listed below will not work for normal users unless users have permission to mount that device If your particular distribution is setup not to allow users to mount partitions its not very hard to change this simply edit the etc fstab file as root and Replace the word defaults with user or A
111. pendix or a front matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document s overall subject or to related matters and contains nothing that could fall directly within that overall subject For example if the Document is in part a textbook of mathematics a Secondary Section may not explain any mathematics The relationship could be a matter of historical connection with the subject or with related matters or of legal commercial philosophical ethical or political position regarding them The Invariant Sections are certain Secondary Sections whose titles are designated as being those of Invariant Sections in the notice that says that the Document is released under this License The Cover Texts are certain short passages of text that are listed as Front Cover Texts or Back Cover Texts in the notice that says that the Document is released under this License A Transparent copy of the Document means a machine readable copy represented in a format whose specification is available to the general public whose contents can be viewed and edited directly and straightforwardly with generic text editors or for images composed of pixels generic paint programs or for drawings some widely available drawing editor and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters A copy made in
112. ppend this to the end of another command For example make some file 2 dev null This will run make on a file and send all error output to dev null The pipe command allows the output of one command to be sent to the input of another For example Gare enisl eue sexnlkewstsaE Jhesis Concatenates the files together then runs ess on them If you are only going to look at a single file you would simply use less on the file Sends output of a program to a file and to standard output Think of it as a T intersection it goes two ways For example ls home user tee my directories txt Lists the files displays the output on the screen and sends the output to a file my directories txt Redirects standard output and error output to a specific location For example make amp dev null Sends both error output and standard output to dev null so you won t see anything Chapter 6 Directing Input Output 18 GNU Linux Command Line Tools Summary 6 3 Command Substitution Command substitution is basically another way to do a pipe you can use pipes and command substitution interchangeably it s up to you which one you find easier Command substitution can be done in two distinct ways Method One back quotes Simply type command 1 command 2 options This will execute command 2 and it s output will become the input to command 1 i Backquote key The back quote key is
113. ption to show detailed information on the particular file s Command syntax identify image name mogrify is another ImageMagick command which is used to transform images in a number of different ways including scaling rotation and various other effects This command can work on a single file or in batch For example to convert a large number of tiff files to jpeg files you could type iaoxuciitu dte joe o CEEE This command has the power to do a number of things in batch including making thumbnails of sets of images For this you could type 8 mogrify geometry 120x120 jpg showrgb showrgb is used to uncompile an rgb colour name database The default is the one that X was built with This database can be used to find the correct colour combination for a particular colour well it can be used as a rough guide anyway To list the colours from the X database simply type Please note All tools listed excluding showrgb are part of the ImageMagick package Type man ImageMagick for a full list of available commands Or see the ImageMagick site ImageMagick for further information Chapter 16 Graphics tools command line based 75 Chapter 17 Working with MS DOS files Use the mtools programs to work with ms dos based files execute mtools for a full listing of available m tools There are a lot of files within the mtools package for working with ms dos disks also try the info documentation of mtools fo
114. que entries 0 d list only duplicate entries For example Quail ee iple lag Ext This would display any duplicate entries only and a count of the number of times that entry has appeared translation A filter useful to replace all instances of characters in a text file or squeeze the whitespace Example hr sone cable aua VS UV nevi die This will run the cat program on some file the output of this command will be sent to the tr command tr will replace all the instances of 3 with 5 like a search and replace You can also do other things such as cat Some rile c um SPa a2 Stesa S new Cile This will run cat on some_file and convert any capital letters to lowercase letters you could use this to change the case of file names too i Alternatives You can also do a search and replace with a one line Perl command read about it at the end of this section The number lines tool it s default action is to write it s input either the file names given as an argument or the standard input to the standard output Line numbers are added to every line and the text is indented Chapter 11 Text Related Tools 53 GNU Linux Command Line Tools Summary This command can do take some more advanced numbering options simply read the info page on it These advanced options mainly relate to customisation of the numbering including different forms of separation for sections pages footers etc Also try cat n
115. r more details The use of slashes Note that with mtools commands you can use the slashes on the a part either way ie backslash windows style or forward slash UNIX system style mformat Formats an unmounted disk as an ms dos floppy disk Usage is similar to the ms dos format utility to format the first floppy disk you can type mformat a mcopy Copies files from an ms dos disk when it s not mounted Similar to the ms dos copy command except it s more advanced Command syntax mcopy a file_or_files destination directory mmount Mount an ms dos disk without using the normal UNIX system mount FT 9 e Pal B o mmount a mnt floppy This will mount the floppy under mnt floppy this option may or may not be necessary it depends on your etc fstab setup mbadblocks Scans an ms dos fat formatted disk for bad blocks it marks any unused bad blocks as bad so they won t be used Example mbadblocks a dosfsck This program is used to check and repair ms dos based filesystems Use the a option to automatically repair the filesystem ie don t ask the user questions the f option to mark un readable clusters as bad and the v option to be more verbose print more information Example dosfsck at dev fd0 This would check your floppy disk for any errors and bad sectors and repair them automatically Chapter 17 Working with MS DOS files 76 Chapter 18 Scheduling Com
116. r to find part of a phrase in a text file There are many uses for wildcards there are two different major ways that wildcards are used they are globbing patterns standard wildcards that are often used by the shell The alternative is regular expressions popular with many other commands and popular for use with text searching and manipulation i Tip If you have a file with wildcard expressions in it then you can use single quotes to stop bash expanding them or use backslashes escape characters or both For example if you wanted to create a file called fo fo and asterisk you would have to do it like this note that you shouldn t create files with names like this this is just an example Note that parts of both subsections on wildcards are based at least in part off the grep manual and info pages Please see the Bibliography for further information Chapter 20 Mini Guides 82 GNU Linux Command Line Tools Summary 20 4 1 Standard Wildcards globbing patterns Standard wildcards also known as globbing patterns are used by various command line utilities to work with multiple files For more information on standard wildcards globbing patterns refer to the manual page by typing 5 Can be used by Standard wildcards are used by nearly any command including mv cp rm and many others question mark this can represent any single character If you specified something at the command line like hd GNU Linux would loo
117. rarely required in GNU Linux most checking is automated on start up if it is required If you do need to check the hard disk for errors you will first need to unmount it Then use the file system checker fsck Chapter 20 Mini Guides 81 GNU Linux Command Line Tools Summary fsck file system type If you had an ext3 file system then it would be fsck ext3 i Also try You can also try using fsck t file system typ 20 3 Duplicating disks This simple technique shows you how you would duplicate floppy disks in a GNU Linux system using dd This technique is not as useful as it used to be but can still be used for creating an image of a cd although that is best done through the cd burning program This information has been taken from the Linux Online Classroom see 4 in the Bibliography for further details dd if dev fd0 of floppy image dd if floppy image of dev fd0 The first dd makes an exact image of the floppy to the file floppy image the second one writes the image to the floppy The user has presumably switched the floppy before the second command Otherwise the command pair is of doubtful usefulness Similar techinques can be used when creating bootdisks you simply use dd to transfer the image to the floppy disk 20 4 Wildcards Wildcards are useful in many ways for a GNU Linux system and for various other uses Commands can use wildcards to perform actions on more than one file at a time o
118. ring more than 100 you must either include a machine readable Transparent copy along with each Opaque copy or state in or with each Opaque copy a publicly accessible computer network location containing a complete Transparent copy of the Document free of added material which the general network using public has access to download anonymously at no charge using public standard network protocols If you use the latter option you must take reasonably prudent steps when you begin distribution of Opaque copies in quantity to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy directly or through your agents or retailers of that edition to the public It is requested but not required that you contact the authors of the Document well before redistributing any large number of copies to give them a chance to provide you with an updated version of the Document A 3 5 MODIFICATIONS You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above provided that you release the Modified Version under precisely this License with the Modified Appendix A Appendix 91 GNU Linux Command Line Tools Summary Version filling the role of the Document thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it In addition you must do these things in the Modified
119. risk is used to match any string equivalent to in standard wildcards asterisk the proceeding item is to be matched zero or more times ie n will match n nn nnnn nnnnnnn but not na or any other character caret means the beginning of the line So a means find a line starting with an a dollar sign means the end of the line So a means find a line ending with an a For example this command searches the file myfile for lines starting with an s and ending with an n and prints them to the standard output screen square brackets specifies a range If you did m a o u m it can become mam mum mom if you did m a d m it can become anything that starts and ends with m and has any character a to d inbetween For example these would work mam mbm mcm mdm This kind of wildcard specifies an or relationship you only need one to match This wildcard makes a logical OR relationship between wildcards This way you can search for something or something else possibly using two different regular expressions You may need to add a backslash before this command to work because the shell may attempt to interpret this as a pipe This is the equivalent of in standard wildcards This performs a logical not This will match anything that is not listed within those square brackets For example rm myfile 9 will remove all myfiles 1e myfiles1 myfiles2 etc but won t remove a file with the
120. s You may extract a single document from such a collection and distribute it individually under this License provided you insert a copy of this License into the extracted document and follow this License in all other respects regarding verbatim copying of that document A 3 8 AGGREGATION WITH INDEPENDENT WORKS A compilation of the Document or its derivatives with other separate and independent documents or works in or on a volume of a storage or distribution medium does not as a whole count as a Modified Version of the Document provided no compilation copyright is claimed for the compilation Such a compilation is called an aggregate and this License does not apply to the other self contained works thus compiled with the Document on account of their being thus compiled if they are not themselves derivative works of the Appendix A Appendix 93 GNU Linux Command Line Tools Summary Document If the Cover Text requirement of section 3 is applicable to these copies of the Document then if the Document is less than one quarter of the entire aggregate the Document s Cover Texts may be placed on covers that surround only the Document within the aggregate Otherwise they must appear on covers around the whole aggregate A 3 9 TRANSLATION Translation is considered a kind of modification so you may distribute translations of the Document under the terms of section 4 Replacing Invariant Sections with translations requires special per
121. s together either lines of each file side by side normally separated by a tab stop but you can have any symbols s you like or it can have words from each file the first file then the second file side by side To obtain a list of lines side by side the first lines from the first file on the left side separated by a tab stop then the first lines from the second file You would type paste filel txt file2 txt To have the list displayed in serial first line from first file Tab second line from first file then third and fourth until the end of the first file type paste serial filel txt file2 txt i This command is very simple to understand if you make yourself an example Its much easier if you create an example for yourself With just a couple of lines I used first line first file and first line second file et cetera for a quick example Chapter 11 Text Related Tools 52 expand GNU Linux Command Line Tools Summary Will convert tabs to spaces and output it Use the option t num to specify the size of a tapstop the number of characters between each tab Command syntax expand file name txt unexpand uniq nl Will convert spaces to tabs and output it Command syntax unexpand file name txt Eliminates duplicate entries from a file and it sometimes greatly simplifies the display uniq options 9 c count the number of occurances of each duplicate 9 u list only uni
122. s will display the memory usage including totals in megabytes uptime Print how long the computer has been up how long the computer has been running It also displays the number of users and the processor load how hard the CPU has been working i The w command The w command displays the output of the uptime command when you run this command You could use the w command instead of uptime uname uname is used to print information on the system such as OS type kernel version et cetera Chapter 8 Finding information about the system 33 Xargs GNU Linux Command Line Tools Summary Some uname options 0 a print all the available information m print only information related to the machine itself 9 n print only the machine hostname 9 r print the release number of the current kernel 9 s print the operating system name p print the processor type Command syntax uname options Note that xargs is an advanced confusing yet powerful command xargs is a command used to run other commands as many times as necessary this way it prevents any kind of overload When you run a command then add a I xargs command2 The results of command will be passed to command2 possibly on a line by line basis or something similar Understanding xargs tends to be very difficult and my explanation is not the best Refer to the examples below or try 6 of the Bibliography for an
123. shred has its disadvantages when run on a filesystem First of all since it has to be installed you cannot run shred on your operating systems filesystem you also cannot use shred on a windows machine easily since you cannot install shred on this machine You may like to try alternatives such as the DBAN project that create self booting floppy disks that can completely erase a machines hard disk Chapter 7 Working with the file system 27 du file stat dd GNU Linux Command Line Tools Summary You may also like to see how chattr can assist you in shredding files once they are removed it has similar problems to shred only ext2 and ext3 style filesystems please see Section 14 2 Displays information about file size Use du filename to display the size of a particular file If you use it on directories it will display the information on the size of the files in the directory and each subdirectory Options for du use du option s 9 c this will make du print a grand total after all arguments have being processed 0 s summarises for each argument prints the total h prints things in human readable mode for example printing IM megabyte rather than 1 024 000 bytes Using the hs options on a directory will display the total size of the directory and all subdirectories Command syntax du options file directory or files Example ghi lng s This command will list the size of a
124. specially when working with devices instead of files touch This command is used to create empty files simply do touch file name It is also used to update the timestamps on files touch can be used to change the time and or date of a file cou e 19050 7 0 9 L5 ny iesjoroue e tco TEL This command would change the timestamp on my report txt so that it would look like you created it at 9 15 The first four digits stand for May 7th 0507 in MM DD American style and the last four 0915 the time 9 15 in the morning Instead of using plain numbers to change the time you can use options similar to that of the date tool For example touch d 5 May 2000 some file txt You can also use date instead of d Also have a look at the date command under Section 8 1 for examples on using d and date the syntax for the date part is exactly the same when using d or date split Splits files into several smaller files Use the b xx option to split into xx bytes also try k for kilobytes and m for megabytes You can use it to split text files and any other files you can use cat to re combine the files This may be useful if you have to transfer something to floppy disks or you wish to divide text files into certain sizes Command syntax expdlstie oppidum taille This will split the input file into 1000 lines of input each thats the default and output using the above example with the input name
125. t S esed m reine dise rete tete ederet bese tee reg eacee em UND dec Deed EE 71 15 3 COmDIeSSIOR o reet E He E AE a pee TERRE AEE E EA R edet 72 Chapter 16 Graphics tools command line based esssoescoesooesossssessocesccssecesccescesocesooesosssosssosesosssesesessseso 74 Chapter 17 Working with MS DOS files ee ee esee ee ee eese seen seen se teta setae toas ee ea see ea s tese setae s eaae sean eS 76 Chapter 18 Scheduling Commands to run in the background 4 c eee eee esee ee ee ee eee seen aee tnee 77 Chapter 19 IESIPIHIRR NC H 80 Chapter 20 Mini Guides cei eese ctr Pet nont boe erepto e eoa eoa Ree nes ororo asso oae Pe PESE Pesh SETS R eene o tue Rao e Posee ken Peer eneS 81 20 1 RPM Redhat Package Management System esssesssssseseseeee enne enne 81 20 2 Checking the Hard Disk for errors eeneioe ieren iini anie eieiei enii 81 20 3 Duplicating disks treno eret e ERREUR VOIE Maan CERE MAR e PE EYE ERE ae 82 202 WidCasds 5 ausi eee Hetero eb ence ee tere poete poete ee depo 82 20 4 1 Standard Wildcards globbing patterns eese eene 83 20 4 2 Regular EXpresSIODS c etit rete t eee ehe ce Pee Pr vote dede ee e eee i dnas 83 20 4 3 Useful categories of characters as defined by the POSIX standard 85 Appendix A A TQUISIU IESU Elem 86 A Finding Pack ages ToolS rni
126. t terminal with x terminals or logs out Also try CTRL D Logs out of a terminal also try CTRL D A little command that repeats anything you type Example echo hello world Simply displays hello world Example echo rm R This will output what will be passed to the rm command and therefore what would be deleted putting echo before a command renders it harmless it just expands wildcards so you know what it will do Also try using the e option with echo This will allow you to use the escape character sequences to format the output of a line Such as Xt for tab n for newline etc Chapter 4 Shell Tips 11 GNU Linux Command Line Tools Summary i Using echo to prevent accidents Typing echo command s could save you the trouble of accidentally doing something you didn t expect Using echo allows you to expand the wildcards to understand what will happen before you actually run the command 4 2 The command line history Using the command history Use the up and down key s to scroll through previously typed commands Press Enter to execute them or use the left and right arrow keys to edit the command first Also see history below The history command The history command can be used to list Bash s log of the commands you have typed This log is called the history To access it type history n This will only list the last n commands Type history without options to see the the entire h
127. t to find out for yourself aspell example Chapter 11 Text Related Tools 51 chcase fmt paste GNU Linux Command Line Tools Summary aspell c FILE txt This will run aspell on a particular file called FILE txt aspell will run interactively and prompt for user input ispell example ajsqexedbl Jem s eae This will run ispell on a particular file called FILE txt ispell will run interactively and prompt for user input Is used to change the uppercase letters in a file name to lowercase or vice versa You could also use tr to do the same thing cat fileName txt tr A Z a z gt newFileName txt The above would convert uppercase to lowercase using the the file fileName txt as input and outputting the results to newFileName txt cat fileName txt tr a z A Z newFileName txt The above would convert lowercase to uppercase using the the file fileName txt as input and outputting the results to newFileName txt chcase a perl script can be found at the chcase homepage format a simple text formatter Use fmt with the u option to output text with uniform spacing where the space between words is reduced to one space character and the space between sentences is reduced to two space characters m Pal B 5 e fmt u myessay txt Will make sure the amount of space between sentences is two spaces and the amount of space between words is one space Puts lines from two file
128. ter using set x you can run the command The output printed before the command runs for example ap Jig oF eolor avto Which means that the command is really an alias to run s with the F and color auto options Use a backslash before the command to run it without the alias backslash The backslash escape character can be used before a shell command to override any aliases For example if rm was made into an alias for rm i then typing rm would actually run rm i However typing Vn lets the shell ignore the alias and just run rm its runs exactly what you type this way it won t confirm if you want to delete things d Using rm Please note that the alias for the remove command is there for a reason Using it incorrectly could remove files which you don t want removed Only use vm if you know exactly what you are doing recovering files is not easy rm does not send things to a recycle bin The V character can be used before special characters such as a space or a wildcard to stop bash from trying to expand them You can make a directory name with a space in it using a backslash before the space For example you could type cd My Directory With Spaces which normally wouldn t work Chapter 4 Shell Tips 10 script GNU Linux Command Line Tools Summary The V character can also be used to stop bash from expanding certain symbols as an alternative you could use single quotation m
129. th the file system 24 rm rmdir GNU Linux Command Line Tools Summary Directories are sometimes called folders in other operating systems such as Microsoft Windows Examples mkdir p home matt work maths This would create the directories work and maths under matt s home directory if matt s home directory didn t exist it would create that too mkdir foo This would create a directory in the current path named foo Remove delete a file s or directories s You can use standard wildcards with this command Section 20 4 1 Command syntax rm options file or folder You can of course use standard wildcards to delete multiple files or multiple directories and files Use the R or r option to remove recursively this removes everything within subdirectories Also try the f option to force removal useful when you don t want to be prompted i Disabling Aliases per execution On some systems such as Mandrake an alias will send rm to rm i prompting you for every file you wish to delete To override this use vm R directory using the V disables the alias for this run only Remove an empty directory If you want to remove a directory with files in it type rm R directory read above for information on rm R Command syntax rmdir directory This will only remove directory if it s empty otherwise it will exit with an error message Move a file or a directory to a new location or renam
130. the System cccsscsssscsssscssssccesccssssssssesssseccssssssssscsssssssesssssecessses 32 8 1 Date Time Calendars iab eet ee ie Ds tesa e E te recedat 35 8 2 Finding information about partitions enne nnne 36 Chapter 9 Controlling the SyS em eere ireso eter eene aan na eon a v eta oon De PEN en E PRENNE IE ME eene P RS a Seno n enin Ie sonsssensesesesssenss 37 9 1 Mounting and Unmounting Floppy CDROM Hard drive Partitions eese 37 9 2 Shutting Down Rebooting the Syste eee eesceesseceseeceeeeecseeeaeceeaaeceaceceeeeeceeeeesaeceeaaeneaeeceeeeees 38 9 3 Controlling Processes sic isccceskettackbads i Gee err POE eia eL EHE AEE EERE RE 40 OA Controlling services i eere ett tee eee tete entre ei e ee nt a aa ee i e obe dene eden 44 Chapter 10 Managing US ES oe cose ot rn rot enero eon s ve ee ea eR e reas boe Ne Ee eo ea ge eS Peau ei otros ispo sourre eS e Pe sep oe surasi 45 TOT Usets GIrOUDpS o ehe ent eee tette e orte o se a eere L e Masada A eee eoa debet 45 GNU Linux Command Line Tools Summary Table of Contents Chapter T1 T xt Related T0085 isccccessscssssssetsscsestoonsossesssoscssonssessossnsesesessssecessetssbosnstonessoescesedesdoesestecosonsssensed 47 Tid LextBGOHOrS 4 see oes ee I eS Eee oe een es 47 TL2 Text Viewing Tools tetro Ie Het er RI ie ete ER RE Fee reine taney 47 11 3 Text Information TO0l amp oreet Ie tree ehe rrr re eroe ree oko rodea
131. tions then press e for edit and add single on to the end of the lines that boot the kernel Then hit Enter and press b to boot Lilo If you are using lilo press escape and type linux single and then hit Enter to boot d Security Warning This is also a basic security hazard if you have others using your computer and security is a concern you may like to add a password to your LILO or Grub prompt to stop this from being done The umask is a value set by the shell It controls the default permissions of any file created during that shell session This information is inherited from the shell s parent and is normally set in some configuration file by the root user in my case etc profile umask has an unusual way of doing things to set the umask you must describe file permissions by saying what will be disabled You can do this by doing 777 minus the file permissions you want Note that umask works with numbers only for an explanation please see Section 14 2 For example You want the default during a particular shell session to be equivalent to chmod 750 user has r w x group has r x and other has no permissions then the command you would use would be umask 027 Chapter 14 Security 66 GNU Linux Command Line Tools Summary 14 1 Some basic Security Tools md5sum Compute an md5 checksum 128 bit for file file name to verify it s integrity You normally use the md5sum c option to check against a giv
132. to display lines which do not contain the string 9 n this option displays the line numbers w this option makes grep match the whole word 0 A x or B x where x is a number display x lines After or Before the section where the particular word is found 9 r or rgrep search for text within files recursively This command uses regular expressions for more information please see Section 20 4 2 For example this command would look in the file rpmlist txt for anything starting with rpm grep rpm rpmlist txt Or you could use it like this to search through the output of another file rpm ga grep ogg The first command lists all RPM s installed on your system the second finds any containing the string ogg and outputs them A recursive version of grep this is a different program to grep This will search all the files in the current directory and all it s subdirectories and print the names of the files and the matching line Follows similar syntax to grep see above You could also use grep with the r option to achieve the same affect This version of grep calls grep with the F option This will look for literal strings only it won t use or expand any kind of regular expression For example you could type fgrep a b file txt And fgrep would look for the string a b in the file file txt i Other Versions There are various versions of grep which are des
133. ual Page Red Hat A small section of the RPM manual page was used in the creation of the RPM verifying subsection without any kind of editing 12 Markku Rossi Enscript Manual Page Free Software Foundation The examples for enscript are based off those shown in the enscript manual page 13 Paul Vixie Cron Manual Page 4th Berkeley Distribution The information from the crontab section below and including the table was taken unedited but with small additions from the crontab manual pages Type man 1 crontab and man 5 crontab to access the 2 different manual pages 14 IBM Developerworks Some parts of the IBM Developerworks tutorials have been used in the creation of this document IBM Developerworks frequently publishes new tutorials on a variety of subjects visit the IBM Developerworks Linux site see link above for more information on their GNU Linux tutorials 15 Suso Banderas Num utils homepage The num utils manual pages were used in the creation of the maths section In particular all the description of the num utils tools are based off the manual pages on the num utils homepage 16 Carla Schroder Archive of the LinuxChix posting This particular LinuxChix posting was made through a mailing list discussion about cron under the TechTalk mailing list The posters homepage is http www tuxcomputing com 17 Joe Barr CLI for noobies import display mogrify This particular article by Joe Barr was used in
134. usually located at the same place as the tilde above the Tab key Method Two dollars sign Simply type command 1 command 2 This will execute command 2 and it s output will become the input to command 1 Using the pipe instead You can of course use pipes to do the same thing if you don t know what a pipe is please see Section 6 2 For example instead of doing less cat filel txt file2 txt Ger wile jee tile 0 e desse And end up with exactly the same result it s up to you which way you find easier lt o amp Q o E e o Q 6 4 Performing more than one command Executing the second command only if the first is successful To do this you would type commandl amp amp command2 command will be executed if command successfully completes if commandl fails command2 won t be run This is called a logical AND Executing the second command only if the first fails Chapter 6 Directing Input Output 19 GNU Linux Command Line Tools Summary To do this you would type commandi command2 command will be executed if command does not successfully complete if command is successful command2 won t be run This is called a logical OR Executing commands sequentially To execute commands sequentially regardless of the success failure of the previous you simply type commandi command2 command will execute once commandl has completed i More than two commands You can continue to use
135. ut in this example the current file directory listed within the directory The above command would move every file listed in dirl to dir2 Obviously this command won t be too useful it would be easier to go to dirl and type mv dir2 Here is a more useful example ils s wav Sxeueee i lanes m YY ET nes This would find all wave files within the current directory and convert them to mp3 files encoded with lame and append a mp3 to the end of the filename unfortunately it doesn t remove the wav and so its not too useful but it works 8 1 Date Time Calendars There is one command to change both the date and time on a UNIX like system date there is also a simple calendar utility cal If you are looking to change the timestamps on files please see Chapter 8 date cal Tells you the date and the time and is also used to set the date time To set the date type date MM DD YYYY American style date where MM is month DD is the number of days within the month and YYYY is the year For example to set the date to the 1st January 2000 you would type date 01 01 2000 To set the time where the 5 option is to set a new time type Q I i 0 u F SR 3 a u u Another useful option you can use is date string or d string option to display a date from x days ago or in x days or x weeks months years et cetera See the examples below Examples date date 3 months 1 day ago Will pr
136. ution and awk can perform a similar task or assist by working on a file and printing out certain information its a programming language You will normally find them installed on your GNU Linux system and will find many tutorials all over the internet feel free to look them up if you ever have to perform many similar operations on a text file 11 5 Text Conversion Filter Tools Filters UNIX System dos formats Chapter 11 Text Related Tools The following filters allow you to change text from Dos style to UNIX system style and vice versa or convert a file to other formats Also note that many modern text editors can do this for you 54 GNU Linux Command Line Tools Summary Why use filters Because UNIX systems and Microsoft use two different standards to represent the end of line in an ASCII text file This can sometimes causes problems in editors or viewers which aren t familiar with the other operating systems end of line style The following tools allow you to get around this difference Whats the difference The difference is very simple on a Windows text file a newline is signalled by a carriage return followed by a newline r n in ASCII On a UNIX system a newline is simply a newline n in ASCII dos2unix This converts Microsoft style end of line characters to UNIX system style end of line characters Simply type dos2unix file txt fromdos This does the same as dos2unix above Simply typ
137. you ve found the command you re looking for use Enter to execute it Alternatively using the right or left arrow keys will place the command on an actual command line so you can edit it 4 3 Other Key combinations GNU Linux shells have many shortcut keys which you can use to speed up your work below is a rough list of some also see CTRL R in the history section of the commands over here Section 4 2 CTRL D the end of file EOF key combination can be used to quickly log out of any terminal CTRL D is also used in programs such as at to signal that you have finished typing your commands the EOF command CTRL Z key combination is used to stop a process It can be used to put something in the background temporarily For example if you were editing a file with vim or emacs just press CTRL Z to regain control of the terminal do what you want and then type fg to bring it back For further information please see Section 9 3 i If fg doesn t work If fg doesn t work you may need to type jobs and then fg job_name or fg job_number CTRL A and CTRL E These key combinations are used for going to the start and end of the line on the command line Use CTRL A to jump to the start of the line and CTRL E to jump to the end of the line CTRL K This key combination can be used to cut or delete what is currently in front of the cursor CTRL Y This key combination can be used to paste the last thing you deleted using CTRL K or CTRL W
138. z to read work within a file compressed with bzip2 The tools are bzcat bzless bzgrep You will find some of them mentioned over here Section 15 3 11 3 Text Information Tools style cmp diff Word count count how many words you have in a text document Can also be used to count the lines or bytes within the file Use the options w for words for lines and c for bytes Or simply run wc with no options to get all three Command syntax wc option file txt To run various readability tests on a particular text file Will output scores on a number of different readability tests with no options Command syntax style options text file amp Find style in the diction package This command is part of the diction package and does not appear to be used too often these days Determines whether or not two files differ works on any type of file Very similar to diff only it compares on the binary level instead of just the text Compares two text files and output a difference report sometimes called a diff containing the text that differs between two files Can be used to create a patch file which can be used by patch Example liis rake eE seal se diff will output a gt followed by the line for each line that isn t in the first file but is in the second file and it will output a lt followed by the line for each line that is in the first file but not in the second file Chapter 11

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