SCCS introduction from UCB
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1. cally be in release two To change the release number of an entire system use secs edit r2 SCCS Suppose that after delta 1 2 was stable you made and released a delta 1 3 But this introduced a bug so you made a delta 1 4 to correct it But 1 4 was still buggy and you decided you wanted to go back to the old version You could revert to delta 1 2 by choosing the SID in a get secs get r1 2 prog c This will produce a version of prog c that is delta 1 2 that can be reinstalled so that work can proceed An Introduction to the Source Code Control System PS1 14 5 In some cases you don t know what the SID of the delta you want is However you can revert to the version of the program that was running as of a certain date by using the c cutoff flag For example secs get c800722120000 prog c will retrieve whatever version was current as of July 22 1980 at 12 00 noon Trailing components can be stripped off defaulting to their highest legal value and punctuation can be inserted in the obvious places for example the above line could be equivalently stated secs get c 80 07 22 12 00 00 prog c Suppose that you later decided that you liked the changes in delta 1 4 but that delta 1 3 should be removed You could do this by excluding delta 1 3 secs edit x1 3 prog c When delta 1 5 is made it will include the changes made in delta 1 4 but will exclude the changes made in delta 1 3 You can exclude a range of deltas using a das2. SCCS file When you do a delta of prog c it will be delta 1 4 again The r flag must be specified and the delta that is specified must be a leaf delta i e no other deltas may have been made subsequent to the creation of that delta If you found you edited a file that you did not want to edit you can back out by using sccs unedit prog c If you are working on a project where the SCCS code is in a directory somewhere you may be able to simplify things by using a shell alias For example the alias alias syssccs sccs d usr src will allow you to issue commands such as syssccs edit cmd who c which will look for the file usr src cemd SCCS who c The file who c will always be created in your current directory regardless of the value of the d flag Working on a project with several people has its own set of special problems The main problem occurs when two people modify a file at the same time SCCS prevents this by locking an s file while it is being edited As a result files should not be reserved for editing unless they are actually being edited at the time since this will prevent other people on the project from making necessary changes For example a good scenario for working might be sccs edit a c g c t c Vi a c g c t c do testing of the experimental version secs delget a c g c t c sccs info should respond Nothing being edited make install As a general rule all source files sho
3. is when the directory is being mothballed To do this the command An Introduction to the Source Code Control System PS1 14 9 secs clean can be used This will remove all files for which an s file exists but which is not being edited Frequently there are directories with several largely unrelated programs such as simple commands These can be put into a single makefile LDFLAGS i s prog prog o CC LDFLAGS o prog prog o prog o prog c prog h example example o CC LDFLAGS o example example o example o example c DEFAULT sccs get lt The trick here is that the DEFAULT rule is called every time something is needed that does not exist and no other rule exists to make it The explicit dependency of the o file on the c file is important Another way of doing the same thing is SRCS prog c prog h example c LDFLAGS i s prog prog o CC LDFLAGS o prog prog o prog o prog h example example o CC LDFLAGS o example example o sources SRCS SRCS sccs get There are a couple of advantages to this approach 1 the explicit dependencies of the o on the c files are not needed 2 there is an entry called sources so if you want to get all the sources you can just say make sources and 3 the makefile is less likely to do confusing things since it won t try to get things that do not exist Libraries that are largely static are best updated using explicit commands s
4. 87 lines The file prog c will be created in the current directory The file will be read only to remind you that you are not supposed to change it This copy of the file should not be changed since SCCS is unable to merge the changes back into the s file If you do make changes they will be lost the next time someone does a get To edit a source file you must first get it requesting permission to edit it The edit command is equivalent to using the e flag to get as sccs get e prog c Keep this in mind when reading other documentation sccs edit prog c The response will be the same as with get except that it will also say An Introduction to the Source Code Control System PS1 14 3 New delta 1 2 You then edit it using a standard text editor vi prog c When the desired changes are made you can put your changes into the SCCS file using the delta command sccs delta prog c Delta will prompt you for comments before it merges the changes in At this prompt you should type a one line description of what the changes mean more lines can be entered by ending each line except the last with a backslash Yes this is a stupid default Delta will then type 1 2 5 inserted 3 deleted 84 unchanged saying that delta 1 2 was created and it inserted five lines removed three lines and left 84 lines unchanged Changes to a line are counted as a line deleted and a line inserted The prog c file will be re
5. An Introduction to the Source Code Control System Eric Allman Project Ingres University of California at Berkeley This is version 1 21 of this document It was last modified on 12 5 80 This document gives a quick introduction to using the Source Code Control System SCCS The presentation is geared to programmers who are more concerned with what to do to get a task done rather than how it works for this reason some of the examples are not well explained For details of what the magic options do see the section on Fur ther Information This is a working document Please send any comments or suggestions to eric Berkeley Edu SCCS is a source management system Such a system maintains a record of versions of a system a record is kept with each set of changes of what the changes are why they were made and who made them and when Old versions can be recovered and different versions can be maintained simultaneously In pro jects with more than one person SCCS will insure that two people are not editing the same file at the same time All versions of your program plus the log and other information is kept in a file called the s file There are three major operations that can be performed on the s file 1 Geta file for compilation not for editing This operation retrieves a version of the file from the s file By default the latest version is retrieved This file is intended for compilation printing or wh
6. atever it is specifically NOT intended to be edited or changed in any way any changes made to a file retrieved in this way will probably be lost 2 Geta file for editing This operation also retrieves a version of the file from the s file but this file is intended to be edited and then incorporated back into the s file Only one person may be editing a file at one time 3 Merge a file back into the s file This is the companion operation to 2 A new version number is assigned and comments are saved explaining why this change was made There are a number of terms that are worth learning before we go any farther The s file is a single file that holds all the different versions of your file The s file is stored in differ ential format i e only the differences between versions are stored rather than the entire text of the new version This saves disk space and allows selective changes to be removed later Also included in the s file is some header information for each version including the comments given by the person who created the version explaining why the changes were made Each set of changes to the s file which is approximately but not exactly equivalent to a version of the file is called a delta Although technically a delta only includes the changes made in practice it is usual for each delta to be made with respect to all the deltas that have occurred before This matches nor mal usage where the previous changes are
7. b o z h c o x h y h z h z h x h so that modules will be recompiled if header files change Since make does not do transitive closure on dependencies you may find in some makefiles lines like An Introduction to the Source Code Control System PS1 14 11 z h x h touch z h This would be used in cases where file z h has a line include x h in order to bring the mod date of z h in line with the mod date of x h When you have a makefile such as above the touch command can be removed completely the equivalent effect will be achieved by doing an automatic get on z h The SCCS PWB User s Manual gives a deeper description of how to use SCCS Of particular interest are the numbering of branches the l file which gives a description of what deltas were used on a get and certain other SCCS commands The SCCS manual pages are a good last resort These should be read by software managers and by people who want to know everything about everything Both of these documents were written without the sccs front end in mind so most of the examples are slightly different from those in this document PS1 14 12 An Introduction to the Source Code Control System Quick Reference The following commands should all be preceded with sccs This list is not exhaustive for more options see Further Information get Gets files for compilation not for editing Id keywords are expanded rSID Version to get p Send to standar
8. d keywords are not expanded this is so that after you put them back in to the s file they will be expanded automatically on each new version But notice if you were to get them expanded accidently then your file would appear to be the same version forever more which would of course defeat the purpose Also if you should install a version of the program without expanding the id keywords it will be impossible to tell what version it is since all it will have is W or what ever To put source files into SCCS format run the following shell script from csh mkdir SCCS save foreach i ch sccs admin i i i mv i save i end This will put the named files into s files in the subdirectory SCCS The files will be removed from the current directory and hidden away in the directory save so the next thing you will probably want to do is to get all the files described below When you are convinced that SCCS has correctly created the s files you should remove the directory save If you want to have id keywords in the files it is best to put them in before you create the s files If you do not admin will print No Id Keywords cm7 which is a warning message only To get a copy of the latest version of a file run sccs get prog c SCCS will respond 1 1 87 lines meaning that version 1 1 was retrieved Actually the SID of the final delta applied was 1 1 and that it has
9. d output rather than to the actual file k Don t expand id keywords ilist List of deltas to include xlist List of deltas to exclude m Precede each line with SID of creating delta cdate Don t apply any deltas created after date edit Gets files for editing Id keywords are not expanded Should be matched with a delta com mand rSID Same as get If SID specifies a release that does not yet exist the highest numbered delta is retrieved and the new delta is numbered with SID b Create a branch ilist Same as get xlist Same as get delta Merge a file gotten using edit back into the s file Collect comments about why this delta was made unedit Remove a file that has been edited previously without merging the changes into the s file prt Produce a report of changes t Print the descriptive text e Print nearly everything info Give a list of all files being edited b Ignore branches u user Ignore files not being edited by user check Same as info except that nothing is printed if nothing is being edited and exit status is returned tell Same as info except that one line is produced per file being edited containing only the file name clean Remove all files that can be regenerated from the s file what Find and print id keywords admin Create or set parameters on s files ifile Create using file as the initial contents Z Rebuild the checksum in case the file has been trashed fflag Turn on the
10. example SID 1 5 1 1 The deltas for this version will be numbered 1 5 1 n Deltas in a branch are normally not included when you do a get To get these versions you will have to say PS1 14 8 An Introduction to the Source Code Control System secs get r1 5 1 prog c At some point you will have finished the experiment and if it was successful you will want to incor porate it into the release version But in the meantime someone may have created a delta 1 6 that you don t want to lose The commands secs edit i1 5 1 1 1 5 1 prog c sccs delta prog c will merge all of your changes into the release system If some of the changes conflict get will print an error the generated result should be carefully examined before the delta is made The following technique might be used to maintain a different version of a program First create a directory to contain the new version mkdir newxyz cd newxyz Edit a copy of the program on a branch secs d xyz edit prog c When using the old version be sure to use the b flag to info check tell and clean to avoid confusion For example use sccs info b when in the directory xyz If you want to save a copy of the program still on the branch back in the s file you can use sccs d xyz deledit prog c which will do a delta on the branch and reedit it for you When the experiment is complete merge it back into the s file using delta sccs d xyz delta prog c A
11. flag dflag Turn off delete the flag tfile Replace the descriptive text in the s file with the contents of file If file is omitted the text is deleted Useful for storing documentation or design amp implementation An Introduction to the Source Code Control System PS1 14 13 fix delget deledit documents to insure they get distributed with the s file Useful flags are b Allow branches to be made using the b flag to edit dsID Default SID to be used on a get or edit i Cause No Id Keywords error message to be a fatal error rather than a warning t The module type the value of this flag replaces the Y keyword Remove a delta and reedit it Do a delta followed by a get Do a delta followed by an edit Z Expands to for the what command to find M The current module name e g prog c PI The highest SID applied W A shorthand for Z M lt tab gt 1 G The date of the delta corresponding to the I keyword PR The current release number i e the first component of the 1 keyword Y Replaced by the value of the t flag set by admin
12. h For example if you want to get rid of 1 3 and 1 4 you can use secs edit x1 3 1 4 prog c which will exclude all deltas from 1 3 to 1 4 Alternatively secs edit x1 3 1 prog c will exclude a range of deltas from 1 3 to the current highest delta in release 1 In certain cases when using x or i see below there will be conflicts between versions for exam ple it may be necessary to both include and delete a particular line If this happens SCCS always prints out a message telling the range of lines effected these lines should then be examined very carefully to see if the version SCCS got is ok Since each delta in the sense of a set of changes can be excluded at will that this makes it most useful to put each semantically distinct change into its own delta When you created a delta you presumably gave a reason for the delta to the comments prompt To print out these comments later use sccs prt prog c This will produce a report for each delta of the SID time and date of creation user who created the delta number of lines inserted deleted and unchanged and the comments associated with the delta For exam ple the output of the above command might be D 1 2 80 08 29 12 35 31 bill 2 1 00005 00003 00084 removed q option D 1 1 79 02 05 00 19 31 eric 1 0 00087 00000 00000 date and time created 80 06 10 00 19 31 by eric To find out why you inserted lines you can get a copy of the file with each l
13. ince make doesn t know about updating them properly However libraries that are in the process of being developed can be handled quite adequately The problem is that the o files have to be kept out of the library as well as in the library PS1 14 10 configuration information OBJS a o b o c o d o SRCS a c b c c c d s x h y h z h TARG usr lib programs GET sccs get REL AR ar RANLIB ranlib lib a OBJS AR rvu lib a OBJS RANLIB lib a install lib a sccs check cp lib a TARG lib a RANLIB TARG lib a sources SRCS SRCS GET REL print sources pr h cs clean rm f o rm f core a out LIB An Introduction to the Source Code Control System The REL in the get can be used to get old versions easily for example make b o REL r1 3 The install entry includes the line sccs check before anything else This guarantees that all the s files are up to date i e nothing is being edited and will abort the make if this condition is not met OBJS a o b o c o d o SRCS a c b c c y d s x h y h z h GET sccs get REL a out OBJS CC LDFLAGS OBJS LIBS sources SRCS SRCS GET REL The print and clean entries are identical to the previous case This makefile requires copies of the source and object files to be kept during development It is probably also wise to include lines of the form a o X h y h
14. ine preceded by the SID that created it sccs get m prog c You can then find out what this delta did by printing the comments using prt To find out what lines are associated with a particular delta e g 1 3 use sccs get m p prog c grep 1 37 The p flag causes SCCS to output the generated source to the standard output rather than to a file When you are editing a file you can find out what changes you have made using secs diffs prog c Most of the diff flags can be used To pass the c flag use C PS1 14 6 An Introduction to the Source Code Control System To compare two versions that are in deltas use secs sccsdiff r1 3 r1 6 prog c to see the differences between delta 1 3 and delta 1 6 There are several sequences of commands that get executed frequently Sccs tries to make it easy to do these A frequent requirement is to make a delta of some file and then get that file This can be done by using sccs delget prog c which is entirely equivalent to using secs delta prog c sccs get prog c The deledit command is equivalent to delget except that the edit command is used instead of the get command Frequently there are small bugs in deltas e g compilation errors for which there is no reason to maintain an audit trail To replace a delta use secs fix r1 4 prog c This will get a copy of delta 1 4 of prog c for you to edit and then delete delta 1 4 from the
15. ive files being edited by you The u flag takes an optional user argument giving only files being edited by that user For example secs info ujohn gives a listing of files being edited by john Id keywords can be inserted into your file that will be expanded automatically by get For example a line such as static char SccsId W t G will be replaced with something like static char SccsId prog c 1 2 08 29 80 This tells you the name and version of the source file and the time the delta was created The string PS1 14 4 An Introduction to the Source Code Control System is a special string which signals the beginning of an SCCS Id keyword To find out what version of a program is being run use sccs what prog c usr bin prog which will print all strings it finds that begin with This works on all types of files including binaries and libraries For example the above command will output something like prog c prog c 1 2 08 29 80 usr bin prog prog c 1 1 02 05 79 From this I can see that the source that I have in prog c will not compile into the same version as the binary in usr bin prog ID keywords can be inserted anywhere including in comments but Id Keywords that are compiled into the object module are especially useful since it lets you find out what version of the object is being run as well as the source However there is a cost data space is used up to store the
16. keywords and on small address space machines this may be prohibitive When you put id keywords into header files it is important that you assign them to different vari ables For example you might use static char AccessSid W G in the file access h and static char OpsysSid 7W G in the file opsys h Otherwise you will get compilation errors because SccsId is redefined The prob lem with this is that if the header file is included by many modules that are loaded together the version number of that header file is included in the object module many times you may find it more to your taste to put id keywords in header files in comments With some care it is possible to keep the SID s consistent in multi file systems The trick here is to always edit all files at once The changes can then be made to whatever files are necessary and then all files even those not changed are redeltaed This can be done fairly easily by just specifying the name of the directory that the SCCS files are in secs edit SCCS which will edit all files in that directory To make the delta use sccs delta SCCS You will be prompted for comments only once When you want to create a new release of a program you can specify the release number you want to create on the edit command For example sccs edit r2 prog c will cause the next delta to be in release two that is it will be numbered 2 1 Future deltas will automati
17. moved it can be retrieved using get It is probably unwise to make a delta before every recompilation or test otherwise you tend to get a lot of deltas with comments like fixed compilation problem in previous delta or fixed botch in 1 3 However it is very important to delta everything before installing a module for general use A good tech nique is to edit the files you need make all necessary changes and tests compiling and editing as often as necessary without making deltas When you are satisfied that you have a working version delta everything being edited re get them and recompile everything To find out what files where being edited you can use sccs info to print out all the files being edited and other information such as the name of the user who did the edit Also the command sccs check is nearly equivalent to the info command except that it is silent if nothing is being edited and returns non zero exit status if anything is being edited it can be used in an install entry in a makefile to abort the install if anything has not been properly deltaed If you know that everything being edited should be deltaed you can use sccs delta sccs tell The tell command is similar to info except that only the names of files being edited are output one per line All of these commands take a b flag to ignore branches alternate versions described later and the u flag to only g
18. not saved at all so all changes are automatically based on all other changes that have happened through history However it is possible to get a version of the file that has selected deltas removed out of the middle of the list of changes equivalent to removing your changes An Introduction to the Source Code Control System PS1 14 1 PS1 14 2 An Introduction to the Source Code Control System later A SID SCCS Id is a number that represents a delta This is normally a two part number consisting of a release number and a level number Normally the release number stays the same however it is possible to move into a new release if some major change is being made Since all past deltas are normally applied the SID of the final delta applied can be used to represent a version number of the file as a whole When you get a version of a file with intent to compile and install it i e something other than edit it some special keywords are expanded inline by SCCS These Jd Keywords can be used to include the current version number or other information into the file All id keywords are of the form x where x is an upper case letter For example I is the SID of the latest delta applied W includes the module name SID and a mark that makes it findable by a program and G is the date of the latest delta applied There are many others most of which are of dubious usefulness When you get a file for editing the i
19. nstrains the version to a particular release only i Give a fatal error if there are no Id Keywords in a file This is useful to guarantee that a version of the file does not get merged into the s file that has the Id Keywords inserted as constants instead of internal forms y The type of the module Actually the value of this flag is unused by SCCS except that it replaces the Y keyword The tfile flag can be used to store descriptive text from file This descriptive text might be the docu mentation or a design and implementation document Using the t flag insures that if the SCCS file is sent the documentation will be sent also If file is omitted the descriptive text is deleted To see the descriptive text use prt t The admin command can be used safely any number of times on files A file need not be gotten for admin to work Sometimes it is convenient to maintain an experimental version of a program for an extended period while normal maintenance continues on the version in production This can be done using a branch Normally deltas continue in a straight line each depending on the delta before Creating a branch forks off a version of the program The ability to create branches must be enabled in advance using sccs admin fb prog c The fb flag can be specified when the SCCS file is first created To create a branch use sccs edit b prog c This will create a branch with for
20. t this point you must decide whether this version should be merged back into the trunk i e the default version which may have undergone changes If so it can be merged using the i flag to edit as described above Branches should be kept to a minimum After the first branch from the trunk SID s are assigned rather haphazardly and the structure gets complex fast SCCS and make can be made to work together with a little care A few sample makefiles for common applications are shown There are a few basic entries that every makefile ought to have These are a out or whatever the makefile generates This entry regenerates whatever this makefile is supposed to regenerate If the makefile regenerates many things this should be called all and should in turn have dependencies on everything the makefile can generate install Moves the objects to the final resting place doing any special chmod s or ranlib s as appropriate sources Creates all the source files from SCCS files clean Removes all files from the current directory that can be regenerated from SCCS files print Prints the contents of the directory The examples shown below are only partial examples and may omit some of these entries when they are deemed to be obvious The clean entry should not remove files that can be regenerated from the SCCS files It is sufficiently important to have the source files around at all times that the only time they should be removed
21. uld be deltaed before installing the program for general use This will insure that it is possible to restore any version in use at any time An Introduction to the Source Code Control System PS1 14 7 Sometimes you may find that you have destroyed or trashed a file that you were trying to edit Or given up and decided to start over Unfortunately you can t just remove it and re edit it SCCS keeps track of the fact that someone is trying to edit it so it won t let you do it again Neither can you just get it using get since that would expand the Id keywords Instead you can say sccs get k prog c This will not expand the Id keywords so it is safe to do a delta with it Alternately you can unedit and edit the file In particularly bad circumstances the SCCS file itself may get munged The most common way this happens is that it gets edited Since SCCS keeps a checksum you will get errors every time you read the file To fix this checksum use sccs admin z prog c There are a number of parameters that can be set using the admin command The most interesting of these are flags Flags can be added by using the f flag For example sccs admin fd1 prog c sets the d flag to the value 1 This flag can be deleted by using sccs admin dd prog c The most useful flags are b Allow branches to be made using the b flag to edit dSID Default SID to be used on a get or edit If this is just a release number it co
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