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This is Info file cvs.info, produced by Makeinfo version 1.67 from the input file ./cvs.texinfo. START-INFO-DIR-ENTRY * CVS: (cvs). Concurrent Versions System END-INFO-DIR-ENTRY Copyright (C) 1992, 1993 Signum Support AB Copyright (C) 1993, 1994 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Free Software Foundation. File: cvs.info, Node: Informing others, Next: Concurrency, Prev: Conflicts example, Up: Multiple developers Informing others about commits ============================== It is often useful to inform others when you commit a new revision of a file. The `-i' option of the `modules' file, or the `loginfo' file, can be used to automate this process. *Note modules::. *Note loginfo::. You can use these features of CVS to, for instance, instruct CVS to mail a message to all developers, or post a message to a local newsgroup. File: cvs.info, Node: Concurrency, Next: Watches, Prev: Informing others, Up: Multiple developers Several developers simultaneously attempting to run CVS ======================================================= If several developers try to run CVS at the same time, one may get the following message: [11:43:23] waiting for bach's lock in /usr/local/cvsroot/foo CVS will try again every 30 seconds, and either continue with the operation or print the message again, if it still needs to wait. If a lock seems to stick around for an undue amount of time, find the person holding the lock and ask them about the cvs command they are running. If they aren't running a cvs command, look in the repository directory mentioned in the message and remove files which they own whose names start with `#cvs.rfl', `#cvs.wfl', or `#cvs.lock'. Note that these locks are to protect CVS's internal data structures and have no relationship to the word "lock" in the sense used by RCS--which refers to reserved checkouts (*note Multiple developers::.). Any number of people can be reading from a given repository at a time; only when someone is writing do the locks prevent other people from reading or writing. One might hope for the following property If someone commits some changes in one cvs command, then an update by someone else will either get all the changes, or none of them. but CVS does *not* have this property. For example, given the files a/one.c a/two.c b/three.c b/four.c if someone runs cvs ci a/two.c b/three.c and someone else runs `cvs update' at the same time, the person running `update' might get only the change to `b/three.c' and not the change to `a/two.c'. File: cvs.info, Node: Watches, Next: Choosing a model, Prev: Concurrency, Up: Multiple developers Mechanisms to track who is editing files ======================================== For many groups, use of CVS in its default mode is perfectly satisfactory. Users may sometimes go to check in a modification only to find that another modification has intervened, but they deal with it and proceed with their check in. Other groups prefer to be able to know who is editing what files, so that if two people try to edit the same file they can choose to talk about who is doing what when rather than be surprised at check in time. The features in this section allow such coordination, while retaining the ability of two developers to edit the same file at the same time. For maximum benefit developers should use `cvs edit' (not `chmod') to make files read-write to edit them, and `cvs release' (not `rm') to discard a working directory which is no longer in use, but CVS is not able to enforce this behavior. * Menu: * Setting a watch:: Telling CVS to watch certain files * Getting Notified:: Telling CVS to notify you * Editing files:: How to edit a file which is being watched * Watch information:: Information about who is watching and editing * Watches Compatibility:: Watches interact poorly with CVS 1.6 or earlier File: cvs.info, Node: Setting a watch, Next: Getting Notified, Up: Watches Telling CVS to watch certain files ---------------------------------- To enable the watch features, you first specify that certain files are to be watched. - Command: cvs watch on [`-lR'] FILES ... Specify that developers should run `cvs edit' before editing FILES. CVS will create working copies of FILES read-only, to remind developers to run the `cvs edit' command before working on them. If FILES includes the name of a directory, CVS arranges to watch all files added to the corresponding repository directory, and sets a default for files added in the future; this allows the user to set notification policies on a per-directory basis. The contents of the directory are processed recursively, unless the `-l' option is given. The `-R' option can be used to force recursion if the `-l' option is set in `~/.cvsrc' (*note ~/.cvsrc::.). If FILES is omitted, it defaults to the current directory. - Command: cvs watch off [`-lR'] FILES ... Do not provide notification about work on FILES. CVS will create working copies of FILES read-write. The FILES and options are processed as for `cvs watch on'. File: cvs.info, Node: Getting Notified, Next: Editing files, Prev: Setting a watch, Up: Watches Telling CVS to notify you ------------------------- You can tell CVS that you want to receive notifications about various actions taken on a file. You can do this without using `cvs watch on' for the file, but generally you will want to use `cvs watch on', so that developers use the `cvs edit' command. - Command: cvs watch add [`-a' ACTION] [`-lR'] FILES ... Add the current user to the list of people to receive notification of work done on FILES. The `-a' option specifies what kinds of events CVS should notify the user about. ACTION is one of the following: `edit' Another user has applied the `cvs edit' command (described below) to a file. `unedit' Another user has applied the `cvs unedit' command (described below) or the `cvs release' command to a file, or has deleted the file and allowed `cvs update' to recreate it. `commit' Another user has committed changes to a file. `all' All of the above. `none' None of the above. (This is useful with `cvs edit', described below.) The `-a' option may appear more than once, or not at all. If omitted, the action defaults to `all'. The FILES and options are processed as for the `cvs watch' commands. - Command: cvs watch remove [`-a' ACTION] [`-lR'] FILES ... Remove a notification request established using `cvs watch add'; the arguments are the same. If the `-a' option is present, only watches for the specified actions are removed. When the conditions exist for notification, CVS calls the `notify' administrative file. Edit `notify' as one edits the other administrative files (*note Intro administrative files::.). This file follows the usual conventions for administrative files (*note syntax::.), where each line is a regular expression followed by a command to execute. The command should contain a single ocurrence of `%s' which will be replaced by the user to notify; the rest of the information regarding the notification will be supplied to the command on standard input. The standard thing to put in the `notify' file is the single line: ALL mail %s -s \"CVS notification\" This causes users to be notified by electronic mail. Note that if you set this up in the straightforward way, users receive notifications on the server machine. One could of course write a `notify' script which directed notifications elsewhere, but to make this easy, CVS allows you to associate a notification address for each user. To do so create a file `users' in `CVSROOT' with a line for each user in the format USER:VALUE. Then instead of passing the name of the user to be notified to `notify', CVS will pass the VALUE (normally an email address on some other machine). CVS does not notify you for your own changes. Currently this check is done based on whether the user name of the person taking the action which triggers notification matches the user name of the person getting notification. In fact, in general, the watches features only track one edit by each user. It probably would be more useful if watches tracked each working directory separately, so this behavior might be worth changing. File: cvs.info, Node: Editing files, Next: Watch information, Prev: Getting Notified, Up: Watches How to edit a file which is being watched ----------------------------------------- Since a file which is being watched is checked out read-only, you cannot simply edit it. To make it read-write, and inform others that you are planning to edit it, use the `cvs edit' command. Some systems call this a "checkout", but CVS uses that term for obtaining a copy of the sources (*note Getting the source::.), an operation which those systems call a "get" or a "fetch". - Command: cvs edit [OPTIONS] FILES ... Prepare to edit the working files FILES. CVS makes the FILES read-write, and notifies users who have requested `edit' notification for any of FILES. The `cvs edit' command accepts the same OPTIONS as the `cvs watch add' command, and establishes a temporary watch for the user on FILES; CVS will remove the watch when FILES are `unedit'ed or `commit'ted. If the user does not wish to receive notifications, she should specify `-a none'. The FILES and options are processed as for the `cvs watch' commands. *Caution:* If the `PreservePermissions' option is enabled in the repository (*note config::.), CVS will not change the permissions on any of the FILES. The reason for this change is to ensure that using `cvs edit' does not interfere with the ability to store file permissions in the CVS repository. Normally when you are done with a set of changes, you use the `cvs commit' command, which checks in your changes and returns the watched files to their usual read-only state. But if you instead decide to abandon your changes, or not to make any changes, you can use the `cvs unedit' command. - Command: cvs unedit [`-lR'] FILES ... Abandon work on the working files FILES, and revert them to the repository versions on which they are based. CVS makes those FILES read-only for which users have requested notification using `cvs watch on'. CVS notifies users who have requested `unedit' notification for any of FILES. The FILES and options are processed as for the `cvs watch' commands. If watches are not in use, the `unedit' command probably does not work, and the way to revert to the repository version is to remove the file and then use `cvs update' to get a new copy. The meaning is not precisely the same; removing and updating may also bring in some changes which have been made in the repository since the last time you updated. When using client/server CVS, you can use the `cvs edit' and `cvs unedit' commands even if CVS is unable to succesfully communicate with the server; the notifications will be sent upon the next successful CVS command. File: cvs.info, Node: Watch information, Next: Watches Compatibility, Prev: Editing files, Up: Watches Information about who is watching and editing --------------------------------------------- - Command: cvs watchers [`-lR'] FILES ... List the users currently watching changes to FILES. The report includes the files being watched, and the mail address of each watcher. The FILES and options are processed as for the `cvs watch' commands. - Command: cvs editors [`-lR'] FILES ... List the users currently working on FILES. The report includes the mail address of each user, the time when the user began working with the file, and the host and path of the working directory containing the file. The FILES and options are processed as for the `cvs watch' commands. File: cvs.info, Node: Watches Compatibility, Prev: Watch information, Up: Watches Using watches with old versions of CVS -------------------------------------- If you use the watch features on a repository, it creates `CVS' directories in the repository and stores the information about watches in that directory. If you attempt to use CVS 1.6 or earlier with the repository, you get an error message such as the following (all on one line): cvs update: cannot open CVS/Entries for reading: No such file or directory and your operation will likely be aborted. To use the watch features, you must upgrade all copies of CVS which use that repository in local or server mode. If you cannot upgrade, use the `watch off' and `watch remove' commands to remove all watches, and that will restore the repository to a state which CVS 1.6 can cope with. File: cvs.info, Node: Choosing a model, Prev: Watches, Up: Multiple developers Choosing between reserved or unreserved checkouts ================================================= Reserved and unreserved checkouts each have pros and cons. Let it be said that a lot of this is a matter of opinion or what works given different groups' working styles, but here is a brief description of some of the issues. There are many ways to organize a team of developers. CVS does not try to enforce a certain organization. It is a tool that can be used in several ways. Reserved checkouts can be very counter-productive. If two persons want to edit different parts of a file, there may be no reason to prevent either of them from doing so. Also, it is common for someone to take out a lock on a file, because they are planning to edit it, but then forget to release the lock. People, especially people who are familiar with reserved checkouts, often wonder how often conflicts occur if unreserved checkouts are used, and how difficult they are to resolve. The experience with many groups is that they occur rarely and usually are relatively straightforward to resolve. The rarity of serious conflicts may be surprising, until one realizes that they occur only when two developers disagree on the proper design for a given section of code; such a disagreement suggests that the team has not been communicating properly in the first place. In order to collaborate under *any* source management regimen, developers must agree on the general design of the system; given this agreement, overlapping changes are usually straightforward to merge. In some cases unreserved checkouts are clearly inappropriate. If no merge tool exists for the kind of file you are managing (for example word processor files or files edited by Computer Aided Design programs), and it is not desirable to change to a program which uses a mergeable data format, then resolving conflicts is going to be unpleasant enough that you generally will be better off to simply avoid the conflicts instead, by using reserved checkouts. The watches features described above in *Note Watches:: can be considered to be an intermediate model between reserved checkouts and unreserved checkouts. When you go to edit a file, it is possible to find out who else is editing it. And rather than having the system simply forbid both people editing the file, it can tell you what the situation is and let you figure out whether it is a problem in that particular case or not. Therefore, for some groups it can be considered the best of both the reserved checkout and unreserved checkout worlds. File: cvs.info, Node: Revision management, Next: Keyword substitution, Prev: Multiple developers, Up: Top Revision management ******************* If you have read this far, you probably have a pretty good grasp on what CVS can do for you. This chapter talks a little about things that you still have to decide. If you are doing development on your own using CVS you could probably skip this chapter. The questions this chapter takes up become more important when more than one person is working in a repository. * Menu: * When to commit:: Some discussion on the subject File: cvs.info, Node: When to commit, Up: Revision management When to commit? =============== Your group should decide which policy to use regarding commits. Several policies are possible, and as your experience with CVS grows you will probably find out what works for you. If you commit files too quickly you might commit files that do not even compile. If your partner updates his working sources to include your buggy file, he will be unable to compile the code. On the other hand, other persons will not be able to benefit from the improvements you make to the code if you commit very seldom, and conflicts will probably be more common. It is common to only commit files after making sure that they can be compiled. Some sites require that the files pass a test suite. Policies like this can be enforced using the commitinfo file (*note commitinfo::.), but you should think twice before you enforce such a convention. By making the development environment too controlled it might become too regimented and thus counter-productive to the real goal, which is to get software written. File: cvs.info, Node: Keyword substitution, Next: Tracking sources, Prev: Revision management, Up: Top Keyword substitution ******************** As long as you edit source files inside your working copy of a module you can always find out the state of your files via `cvs status' and `cvs log'. But as soon as you export the files from your development environment it becomes harder to identify which revisions they are. CVS can use a mechanism known as "keyword substitution" (or "keyword expansion") to help identifying the files. Embedded strings of the form `$KEYWORD$' and `$KEYWORD:...$' in a file are replaced with strings of the form `$KEYWORD:VALUE$' whenever you obtain a new revision of the file. * Menu: * Keyword list:: Keywords * Using keywords:: Using keywords * Avoiding substitution:: Avoiding substitution * Substitution modes:: Substitution modes * Log keyword:: Problems with the $Log$ keyword. File: cvs.info, Node: Keyword list, Next: Using keywords, Up: Keyword substitution Keyword List ============ This is a list of the keywords: `$Author$' The login name of the user who checked in the revision. `$Date$' The date and time (UTC) the revision was checked in. `$Header$' A standard header containing the full pathname of the RCS file, the revision number, the date (UTC), the author, the state, and the locker (if locked). Files will normally never be locked when you use CVS. `$Id$' Same as `$Header$', except that the RCS filename is without a path. `$Name$' Tag name used to check out this file. `$Locker$' The login name of the user who locked the revision (empty if not locked, and thus almost always useless when you are using CVS). `$Log$' The log message supplied during commit, preceded by a header containing the RCS filename, the revision number, the author, and the date (UTC). Existing log messages are *not* replaced. Instead, the new log message is inserted after `$Log:...$'. Each new line is prefixed with the same string which precedes the `$Log' keyword. For example, if the file contains /* Here is what people have been up to: * * $Log: frob.c,v $ * Revision 1.1 1997/01/03 14:23:51 joe * Add the superfrobnicate option * */ then additional lines which are added when expanding the `$Log' keyword will be preceded by ` * '. Unlike previous versions of CVS and RCS, the "comment leader" from the RCS file is not used. The `$Log' keyword is useful for accumulating a complete change log in a source file, but for several reasons it can be problematic. *Note Log keyword::. `$RCSfile$' The name of the RCS file without a path. `$Revision$' The revision number assigned to the revision. `$Source$' The full pathname of the RCS file. `$State$' The state assigned to the revision. States can be assigned with `cvs admin -s'--see *Note admin options::. File: cvs.info, Node: Using keywords, Next: Avoiding substitution, Prev: Keyword list, Up: Keyword substitution Using keywords ============== To include a keyword string you simply include the relevant text string, such as `$Id$', inside the file, and commit the file. CVS will automatically expand the string as part of the commit operation. It is common to embed the `$Id$' string in the source files so that it gets passed through to generated files. For example, if you are managing computer program source code, you might include a variable which is initialized to contain that string. Or some C compilers may provide a `#pragma ident' directive. Or a document management system might provide a way to pass a string through to generated files. The `ident' command (which is part of the RCS package) can be used to extract keywords and their values from a file. This can be handy for text files, but it is even more useful for extracting keywords from binary files. $ ident samp.c samp.c: $Id: samp.c,v 1.5 1993/10/19 14:57:32 ceder Exp $ $ gcc samp.c $ ident a.out a.out: $Id: samp.c,v 1.5 1993/10/19 14:57:32 ceder Exp $ SCCS is another popular revision control system. It has a command, `what', which is very similar to `ident' and used for the same purpose. Many sites without RCS have SCCS. Since `what' looks for the character sequence `@(#)' it is easy to include keywords that are detected by either command. Simply prefix the RCS keyword with the magic SCCS phrase, like this: static char *id="@(#) $Id: ab.c,v 1.5 1993/10/19 14:57:32 ceder Exp $"; File: cvs.info, Node: Avoiding substitution, Next: Substitution modes, Prev: Using keywords, Up: Keyword substitution Avoiding substitution ===================== Keyword substitution has its disadvantages. Sometimes you might want the literal text string `$Author$' to appear inside a file without CVS interpreting it as a keyword and expanding it into something like `$Author: ceder $'. There is unfortunately no way to selectively turn off keyword substitution. You can use `-ko' (*note Substitution modes::.) to turn off keyword substitution entirely. In many cases you can avoid using keywords in the source, even though they appear in the final product. For example, the source for this manual contains `$@asis{}Author$' whenever the text `$Author$' should appear. In `nroff' and `troff' you can embed the null-character `\&' inside the keyword for a similar effect. File: cvs.info, Node: Substitution modes, Next: Log keyword, Prev: Avoiding substitution, Up: Keyword substitution Substitution modes ================== Each file has a stored default substitution mode, and each working directory copy of a file also has a substitution mode. The former is set by the `-k' option to `cvs add' and `cvs admin'; the latter is set by the `-k' or `-A' options to `cvs checkout' or `cvs update'. `cvs diff' also has a `-k' option. For some examples, see *Note Binary files::. The modes available are: `-kkv' Generate keyword strings using the default form, e.g. `$Revision: 5.7 $' for the `Revision' keyword. `-kkvl' Like `-kkv', except that a locker's name is always inserted if the given revision is currently locked. This option is normally not useful when CVS is used. `-kk' Generate only keyword names in keyword strings; omit their values. For example, for the `Revision' keyword, generate the string `$Revision$' instead of `$Revision: 5.7 $'. This option is useful to ignore differences due to keyword substitution when comparing different revisions of a file. `-ko' Generate the old keyword string, present in the working file just before it was checked in. For example, for the `Revision' keyword, generate the string `$Revision: 1.1 $' instead of `$Revision: 5.7 $' if that is how the string appeared when the file was checked in. `-kb' Like `-ko', but also inhibit conversion of line endings between the canonical form in which they are stored in the repository (linefeed only), and the form appropriate to the operating system in use on the client. For systems, like unix, which use linefeed only to terminate lines, this is the same as `-ko'. For more information on binary files, see *Note Binary files::. `-kv' Generate only keyword values for keyword strings. For example, for the `Revision' keyword, generate the string `5.7' instead of `$Revision: 5.7 $'. This can help generate files in programming languages where it is hard to strip keyword delimiters like `$Revision: $' from a string. However, further keyword substitution cannot be performed once the keyword names are removed, so this option should be used with care. One often would like to use `-kv' with `cvs export'--*note export::.. But be aware that doesn't handle an export containing binary files correctly. File: cvs.info, Node: Log keyword, Prev: Substitution modes, Up: Keyword substitution Problems with the $Log$ keyword. ================================ The `$Log$' keyword is somewhat controversial. As long as you are working on your development system the information is easily accessible even if you do not use the `$Log$' keyword--just do a `cvs log'. Once you export the file the history information might be useless anyhow. A more serious concern is that CVS is not good at handling `$Log$' entries when a branch is merged onto the main trunk. Conflicts often result from the merging operation. People also tend to "fix" the log entries in the file (correcting spelling mistakes and maybe even factual errors). If that is done the information from `cvs log' will not be consistent with the information inside the file. This may or may not be a problem in real life. It has been suggested that the `$Log$' keyword should be inserted *last* in the file, and not in the files header, if it is to be used at all. That way the long list of change messages will not interfere with everyday source file browsing. File: cvs.info, Node: Tracking sources, Next: Builds, Prev: Keyword substitution, Up: Top Tracking third-party sources **************************** If you modify a program to better fit your site, you probably want to include your modifications when the next release of the program arrives. CVS can help you with this task. In the terminology used in CVS, the supplier of the program is called a "vendor". The unmodified distribution from the vendor is checked in on its own branch, the "vendor branch". CVS reserves branch 1.1.1 for this use. When you modify the source and commit it, your revision will end up on the main trunk. When a new release is made by the vendor, you commit it on the vendor branch and copy the modifications onto the main trunk. Use the `import' command to create and update the vendor branch. When you import a new file, the vendor branch is made the `head' revision, so anyone that checks out a copy of the file gets that revision. When a local modification is committed it is placed on the main trunk, and made the `head' revision. * Menu: * First import:: Importing a module for the first time * Update imports:: Updating a module with the import command * Reverting local changes:: Reverting a module to the latest vendor release * Binary files in imports:: Binary files require special handling * Keywords in imports:: Keyword substitution might be undesirable * Multiple vendor branches:: What if you get sources from several places? File: cvs.info, Node: First import, Next: Update imports, Up: Tracking sources Importing a module for the first time ===================================== Use the `import' command to check in the sources for the first time. When you use the `import' command to track third-party sources, the "vendor tag" and "release tags" are useful. The "vendor tag" is a symbolic name for the branch (which is always 1.1.1, unless you use the `-b BRANCH' flag--*Note Multiple vendor branches::.). The "release tags" are symbolic names for a particular release, such as `FSF_0_04'. Note that `import' does *not* change the directory in which you invoke it. In particular, it does not set up that directory as a CVS working directory; if you want to work with the sources import them first and then check them out into a different directory (*note Getting the source::.). Suppose you have the sources to a program called `wdiff' in a directory `wdiff-0.04', and are going to make private modifications that you want to be able to use even when new releases are made in the future. You start by importing the source to your repository: $ cd wdiff-0.04 $ cvs import -m "Import of FSF v. 0.04" fsf/wdiff FSF_DIST WDIFF_0_04 The vendor tag is named `FSF_DIST' in the above example, and the only release tag assigned is `WDIFF_0_04'. File: cvs.info, Node: Update imports, Next: Reverting local changes, Prev: First import, Up: Tracking sources Updating a module with the import command ========================================= When a new release of the source arrives, you import it into the repository with the same `import' command that you used to set up the repository in the first place. The only difference is that you specify a different release tag this time. $ tar xfz wdiff-0.05.tar.gz $ cd wdiff-0.05 $ cvs import -m "Import of FSF v. 0.05" fsf/wdiff FSF_DIST WDIFF_0_05 For files that have not been modified locally, the newly created revision becomes the head revision. If you have made local changes, `import' will warn you that you must merge the changes into the main trunk, and tell you to use `checkout -j' to do so. $ cvs checkout -jFSF_DIST:yesterday -jFSF_DIST wdiff The above command will check out the latest revision of `wdiff', merging the changes made on the vendor branch `FSF_DIST' since yesterday into the working copy. If any conflicts arise during the merge they should be resolved in the normal way (*note Conflicts example::.). Then, the modified files may be committed. Using a date, as suggested above, assumes that you do not import more than one release of a product per day. If you do, you can always use something like this instead: $ cvs checkout -jWDIFF_0_04 -jWDIFF_0_05 wdiff In this case, the two above commands are equivalent. File: cvs.info, Node: Reverting local changes, Next: Binary files in imports, Prev: Update imports, Up: Tracking sources Reverting to the latest vendor release ====================================== You can also revert local changes completely and return to the latest vendor release by changing the `head' revision back to the vendor branch on all files. For example, if you have a checked-out copy of the sources in `~/work.d/wdiff', and you want to revert to the vendor's version for all the files in that directory, you would type: $ cd ~/work.d/wdiff $ cvs admin -bWDIFF . You must specify the `-bWDIFF' without any space after the `-b'. *Note admin options::. File: cvs.info, Node: Binary files in imports, Next: Keywords in imports, Prev: Reverting local changes, Up: Tracking sources How to handle binary files with cvs import ========================================== Use the `-k' wrapper option to tell import which files are binary. *Note Wrappers::. File: cvs.info, Node: Keywords in imports, Next: Multiple vendor branches, Prev: Binary files in imports, Up: Tracking sources How to handle keyword substitution with cvs import ================================================== The sources which you are importing may contain keywords (*note Keyword substitution::.). For example, the vendor may use CVS or some other system which uses similar keyword expansion syntax. If you just import the files in the default fashion, then the keyword expansions supplied by the vendor will be replaced by keyword expansions supplied by your own copy of CVS. It may be more convenient to maintain the expansions supplied by the vendor, so that this information can supply information about the sources that you imported from the vendor. To maintain the keyword expansions supplied by the vendor, supply the `-ko' option to `cvs import' the first time you import the file. This will turn off keyword expansion for that file entirely, so if you want to be more selective you'll have to think about what you want and use the `-k' option to `cvs update' or `cvs admin' as appropriate. File: cvs.info, Node: Multiple vendor branches, Prev: Keywords in imports, Up: Tracking sources Multiple vendor branches ======================== All the examples so far assume that there is only one vendor from which you are getting sources. In some situations you might get sources from a variety of places. For example, suppose that you are dealing with a project where many different people and teams are modifying the software. There are a variety of ways to handle this, but in some cases you have a bunch of source trees lying around and what you want to do more than anything else is just to all put them in CVS so that you at least have them in one place. For handling situations in which there may be more than one vendor, you may specify the `-b' option to `cvs import'. It takes as an argument the vendor branch to import to. The default is `-b 1.1.1'. For example, suppose that there are two teams, the red team and the blue team, that are sending you sources. You want to import the red team's efforts to branch 1.1.1 and use the vendor tag RED. You want to import the blue team's efforts to branch 1.1.3 and use the vendor tag BLUE. So the commands you might use are: $ cvs import dir RED RED_1-0 $ cvs import -b 1.1.3 dir BLUE BLUE_1-5 Note that if your vendor tag does not match your `-b' option, CVS will not detect this case! For example, $ cvs import -b 1.1.3 dir RED RED_1-0 Be careful; this kind of mismatch is sure to sow confusion or worse. I can't think of a useful purpose for the ability to specify a mismatch here, but if you discover such a use, don't. CVS is likely to make this an error in some future release. File: cvs.info, Node: Builds, Next: Special Files, Prev: Tracking sources, Up: Top How your build system interacts with CVS **************************************** As mentioned in the introduction, CVS does not contain software for building your software from source code. This section describes how various aspects of your build system might interact with CVS. One common question, especially from people who are accustomed to RCS, is how to make their build get an up to date copy of the sources. The answer to this with CVS is two-fold. First of all, since CVS itself can recurse through directories, there is no need to modify your `Makefile' (or whatever configuration file your build tool uses) to make sure each file is up to date. Instead, just use two commands, first `cvs -q update' and then `make' or whatever the command is to invoke your build tool. Secondly, you do not necessarily *want* to get a copy of a change someone else made until you have finished your own work. One suggested approach is to first update your sources, then implement, build and test the change you were thinking of, and then commit your sources (updating first if necessary). By periodically (in between changes, using the approach just described) updating your entire tree, you ensure that your sources are sufficiently up to date. One common need is to record which versions of which source files went into a particular build. This kind of functionality is sometimes called "bill of materials" or something similar. The best way to do this with CVS is to use the `tag' command to record which versions went into a given build (*note Tags::.). Using CVS in the most straightforward manner possible, each developer will have a copy of the entire source tree which is used in a particular build. If the source tree is small, or if developers are geographically dispersed, this is the preferred solution. In fact one approach for larger projects is to break a project down into smaller separately-compiled subsystems, and arrange a way of releasing them internally so that each developer need check out only those subsystems which are they are actively working on. Another approach is to set up a structure which allows developers to have their own copies of some files, and for other files to access source files from a central location. Many people have come up with some such a system using features such as the symbolic link feature found in many operating systems, or the `VPATH' feature found in many versions of `make'. One build tool which is designed to help with this kind of thing is Odin (see `ftp://ftp.cs.colorado.edu/pub/distribs/odin'). File: cvs.info, Node: Special Files, Next: CVS commands, Prev: Builds, Up: Top Special Files ************* In normal circumstances, CVS works only with regular files. Every file in a project is assumed to be persistent; it must be possible to open, read and close them; and so on. CVS also ignores file permissions and ownerships, leaving such issues to be resolved by the developer at installation time. In other words, it is not possible to "check in" a device into a repository; if the device file cannot be opened, CVS will refuse to handle it. Files also lose their ownerships and permissions during repository transactions. If the configuration variable `PreservePermissions' (*note config::.) is set in the repository, CVS will save the following file characteristics in the repository: * user and group ownership * permissions * major and minor device numbers * symbolic links * hard link structure Using the `PreservePermissions' option affects the behavior of CVS in several ways. First, some of the new operations supported by CVS are not accessible to all users. In particular, file ownership and special file characteristics may only be changed by the superuser. When the `PreservePermissions' configuration variable is set, therefore, users will have to be `root' in order to perform CVS operations. When `PreservePermissions' is in use, some CVS operations (such as `cvs status') will not recognize a file's hard link structure, and so will emit spurious warnings about mismatching hard links. The reason is that CVS's internal structure does not make it easy for these operations to collect all the necessary data about hard links, so they check for file conflicts with inaccurate data. A more subtle difference is that CVS considers a file to have changed only if its contents have changed (specifically, if the modification time of the working file does not match that of the repository's file). Therefore, if only the permissions, ownership or hard linkage have changed, or if a device's major or minor numbers have changed, CVS will not notice. In order to commit such a change to the repository, you must force the commit with `cvs commit -f'. This also means that if a file's permissions have changed and the repository file is newer than the working copy, performing `cvs update' will silently change the permissions on the working copy. Changing hard links in a CVS repository is particularly delicate. Suppose that file `foo' is linked to file `old', but is later relinked to file `new'. You can wind up in the unusual situation where, although `foo', `old' and `new' have all had their underlying link patterns changed, only `foo' and `new' have been modified, so `old' is not considered a candidate for checking in. It can be very easy to produce inconsistent results this way. Therefore, we recommend that when it is important to save hard links in a repository, the prudent course of action is to `touch' any file whose linkage or status has changed since the last checkin. Indeed, it may be wise to `touch *' before each commit in a directory with complex hard link structures. It is worth noting that only regular files may be merged, for reasons that hopefully are obvious. If `cvs update' or `cvs checkout -j' attempts to merge a symbolic link with a regular file, or two device files for different kinds of devices, CVS will report a conflict and refuse to perform the merge. At the same time, `cvs diff' will not report any differences between these files, since no meaningful textual comparisons can be made on files which contain no text. The `PreservePermissions' features do not work with client/server CVS. Another limitation is that hard links must be to other files within the same directory; hard links across directories are not supported. File: cvs.info, Node: CVS commands, Next: Invoking CVS, Prev: Special Files, Up: Top Guide to CVS commands ********************* This appendix describes the overall structure of CVS commands, and describes some commands in detail (others are described elsewhere; for a quick reference to CVS commands, *note Invoking CVS::.). * Menu: * Structure:: Overall structure of CVS commands * Exit status:: Indicating CVS's success or failure * ~/.cvsrc:: Default options with the ~/.csvrc file * Global options:: Options you give to the left of cvs_command * Common options:: Options you give to the right of cvs_command * admin:: Administration * checkout:: Checkout sources for editing * commit:: Check files into the repository * diff:: Show differences between revisions * export:: Export sources from CVS, similar to checkout * history:: Show status of files and users * import:: Import sources into CVS, using vendor branches * log:: Show log messages for files * rdiff:: 'patch' format diffs between releases * release:: Indicate that a Module is no longer in use * rtag:: Add a tag to a module * tag:: Add a tag to checked out version * update:: Bring work tree in sync with repository File: cvs.info, Node: Structure, Next: Exit status, Up: CVS commands Overall structure of CVS commands ================================= The overall format of all CVS commands is: cvs [ cvs_options ] cvs_command [ command_options ] [ command_args ] `cvs' The name of the CVS program. `cvs_options' Some options that affect all sub-commands of CVS. These are described below. `cvs_command' One of several different sub-commands. Some of the commands have aliases that can be used instead; those aliases are noted in the reference manual for that command. There are only two situations where you may omit `cvs_command': `cvs -H' elicits a list of available commands, and `cvs -v' displays version information on CVS itself. `command_options' Options that are specific for the command. `command_args' Arguments to the commands. There is unfortunately some confusion between `cvs_options' and `command_options'. `-l', when given as a `cvs_option', only affects some of the commands. When it is given as a `command_option' is has a different meaning, and is accepted by more commands. In other words, do not take the above categorization too seriously. Look at the documentation instead. File: cvs.info, Node: Exit status, Next: ~/.cvsrc, Prev: Structure, Up: CVS commands CVS's exit status ================= CVS can indicate to the calling environment whether it succeeded or failed by setting its "exit status". The exact way of testing the exit status will vary from one operating system to another. For example in a unix shell script the `$?' variable will be 0 if the last command returned a successful exit status, or greater than 0 if the exit status indicated failure. If CVS is successful, it returns a successful status; if there is an error, it prints an error message and returns a failure status. The one exception to this is the `cvs diff' command. It will return a successful status if it found no differences, or a failure status if there were differences or if there was an error. Because this behavior provides no good way to detect errors, in the future it is possible that `cvs diff' will be changed to behave like the other CVS commands. File: cvs.info, Node: ~/.cvsrc, Next: Global options, Prev: Exit status, Up: CVS commands Default options and the ~/.cvsrc file ===================================== There are some `command_options' that are used so often that you might have set up an alias or some other means to make sure you always specify that option. One example (the one that drove the implementation of the `.cvsrc' support, actually) is that many people find the default output of the `diff' command to be very hard to read, and that either context diffs or unidiffs are much easier to understand. The `~/.cvsrc' file is a way that you can add default options to `cvs_commands' within cvs, instead of relying on aliases or other shell scripts. The format of the `~/.cvsrc' file is simple. The file is searched for a line that begins with the same name as the `cvs_command' being executed. If a match is found, then the remainder of the line is split up (at whitespace characters) into separate options and added to the command arguments *before* any options from the command line. If a command has two names (e.g., `checkout' and `co'), the official name, not necessarily the one used on the command line, will be used to match against the file. So if this is the contents of the user's `~/.cvsrc' file: log -N diff -u update -P checkout -P the command `cvs checkout foo' would have the `-P' option added to the arguments, as well as `cvs co foo'. With the example file above, the output from `cvs diff foobar' will be in unidiff format. `cvs diff -c foobar' will provide context diffs, as usual. Getting "old" format diffs would be slightly more complicated, because `diff' doesn't have an option to specify use of the "old" format, so you would need `cvs -f diff foobar'. In place of the command name you can use `cvs' to specify global options (*note Global options::.). For example the following line in `.cvsrc' cvs -z6 causes CVS to use compression level 6.