     [file CVSvn.texi not included]

Copyright © 1992, 1993 Signum Support AB Copyright © 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 section entitled ``GNU General Public License'' is included exactly as in the original, and provided 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 the section entitled ``GNU General Public License'' and this permission notice may be included in translations approved by the Free Software Foundation instead of in the original English.

This info manual describes how to use and administer CVS version CVSVN.

About this manual
*****************

Up to this point, one of the weakest parts of CVS has been the documentation.  CVS is a complex program.  Previous versions of the manual were written in the manual page format, which is not really well suited for such a complex program.

When writing this manual, I had several goals in mind:

  * No knowledge of RCS should be necessary.

  * No previous knowledge of revision control software should be necessary.  All terms, such as revision numbers, revision trees and merging are explained as they are introduced.

  * The manual should concentrate on the things CVS users want to do, instead of what the CVS commands can do. The first part of this manual leads you through things you might want to do while doing development, and introduces the relevant CVS commands as they are needed.

  * Information should be easy to find.  In the reference manual in the appendices almost all information about every CVS command is gathered together.  There is also an extensive index, and a lot of cross references.

This manual was contributed by Signum Support AB in Sweden.  Signum is yet another in the growing list of companies that support free software.  You are free to copy both this manual and the CVS program. See Copying, for the details.  Signum Support offers support contracts and binary distribution for many programs, such as CVS, GNU Emacs, the GNU C compiler and others.  Write to us for more information.

     Signum Support AB
     Box 2044
     S-580 02  Linkoping
     Sweden

     Email: info@signum.se
     Phone: +46 (0)13 - 21 46 00
     Fax:   +46 (0)13 - 21 47 00

Another company selling support for CVS is Cyclic Software, web: http://www.cyclic.com/, email: info@cyclic.com.

Checklist for the impatient reader
==================================

CVS is a complex system.  You will need to read the manual to be able to use all of its capabilities. There are dangers that can easily be avoided if you know about them, and this manual tries to warn you about them.  This checklist is intended to help you avoid the dangers without reading the entire manual. If you intend to read the entire manual you can skip this table.

Binary files
     CVS can handle binary files, but you must have RCS release 5.5 or later and a release of GNU diff that supports the -a flag (release 1.15 and later are OK).  You must also configure both RCS and CVS to handle binary files when you install them.

     Keword substitution can be a source of trouble with binary files. See Keyword substitution, for solutions.

The admin command
     Careless use of the admin command can cause CVS to cease working.  See admin, before trying to use it.

Credits
=======

Roland Pesch, Cygnus Support <pesch@cygnus.com> wrote the manual pages which were distributed with CVS 1.3.  Appendix A and B contain much text that was extracted from them.  He also read an early draft of this manual and contributed many ideas and corrections.

The mailing-list info-cvs is sometimes informative. I have included information from postings made by the following persons: David G. Grubbs <dgg@think.com>.

Some text has been extracted from the man pages for RCS.

The CVS FAQ by David G. Grubbs has provided useful material.  The FAQ is no longer maintained, however, and this manual about the closest thing there is to a successor (with respect to documenting how to use CVS, at least).

In addition, the following persons have helped by telling me about mistakes I've made: Roxanne Brunskill <rbrunski@datap.ca>, Kathy Dyer <dyer@phoenix.ocf.llnl.gov>, Karl Pingle <pingle@acuson.com>, Thomas A Peterson <tap@src.honeywell.com>, Inge Wallin <ingwa@signum.se>, Dirk Koschuetzki <koschuet@fmi.uni-passau.de> and Michael Brown <brown@wi.extrel.com>.

BUGS
====

This manual is known to have room for improvement. Here is a list of known deficiencies:

  * In the examples, the output from CVS is sometimes displayed, sometimes not.

  * The input that you are supposed to type in the examples should have a different font than the output from the computer.

  * This manual should be clearer about what file permissions you should set up in the repository, and about setuid/setgid.

  * Some of the chapters are not yet complete.  They are noted by comments in the cvs.texinfo file.

  * This list is not complete.  If you notice any error, omission, or something that is unclear, please send mail to bug-cvs@prep.ai.mit.edu.

I hope that you will find this manual useful, despite the above-mentioned shortcomings.

Linkoping, October 1993
Per Cederqvist

What is CVS?
************

CVS is a version control system.  Using it, you can record the history of your source files.

For example, bugs sometimes creep in when software is modified, and you might not detect the bug until a long time after you make the modification. With CVS, you can easily retrieve old versions to see exactly which change caused the bug.  This can sometimes be a big help.

You could of course save every version of every file you have ever created.  This would however waste an enormous amount of disk space.  CVS stores all the versions of a file in a single file in a clever way that only stores the differences between versions.

CVS also helps you if you are part of a group of people working on the same project.  It is all too easy to overwrite each others' changes unless you are extremely careful. Some editors, like GNU Emacs, try to make sure that the same file is never modified by two people at the same time.  Unfortunately, if someone is using another editor, that safeguard will not work.  CVS solves this problem by insulating the different developers from each other.  Every developer works in his own directory, and CVS merges the work when each developer is done.

CVS started out as a bunch of shell scripts written by Dick Grune, posted to comp.sources.unix in the volume 6 release of December, 1986.  While no actual code from these shell scripts is present in the current version of CVS much of the CVS conflict resolution algorithms come from them.

In April, 1989, Brian Berliner designed and coded CVS. Jeff Polk later helped Brian with the design of the CVS module and vendor branch support.

You can get CVS via anonymous ftp from a number of sites, for instance prep.ai.mit.edu in pub/gnu.

There is a mailing list for CVS.  To subscribe or unsubscribe, write to <info-cvs-request@prep.ai.mit.edu>.  Please be specific about your email address.  As of May 1996, subscription requests are handled by a busy human being, so you cannot expect to be added or removed immediately.  The usenet group comp.software.config-mgmt is also a suitable place for CVS discussions (along with other configuration management systems).

CVS is not...
=============

CVS can do a lot of things for you, but it does not try to be everything for everyone.

CVS is not a build system.

     Though the structure of your repository and modules file interact with your build system (e.g. Makefiles), they are essentially independent.

     CVS does not dictate how you build anything.  It merely stores files for retrieval in a tree structure you devise.

     CVS does not dictate how to use disk space in the checked out working directories.  If you write your Makefiles or scripts in every directory so they have to know the relative positions of everything else, you wind up requiring the entire repository to be checked out.

     If you modularize your work, and construct a build system that will share files (via links, mounts, VPATH in Makefiles, etc.), you can arrange your disk usage however you like.

     But you have to remember that any such system is a lot of work to construct and maintain.  CVS does not address the issues involved.

     Of course, you should place the tools created to support such a build system (scripts, Makefiles, etc) under CVS.

     Figuring out what files need to be rebuilt when something changes is, again, something to be handled outside the scope of CVS.  One traditional approach is to use make for building, and use some automated tool for generating the depencies which make uses.

CVS is not a substitute for management.

     Your managers and project leaders are expected to talk to you frequently enough to make certain you are aware of schedules, merge points, branch names and release dates.  If they don't, CVS can't help.

     CVS is an instrument for making sources dance to your tune.  But you are the piper and the composer.  No instrument plays itself or writes its own music.

CVS is not a substitute for developer communication.

     When faced with conflicts within a single file, most developers manage to resolve them without too much effort.  But a more general definition of ``conflict'' includes problems too difficult to solve without communication between developers.

     CVS cannot determine when simultaneous changes within a single file, or across a whole collection of files, will logically conflict with one another.  Its concept of a conflict is purely textual, arising when two changes to the same base file are near enough to spook the merge (i.e. diff3) command.

     CVS does not claim to help at all in figuring out non-textual or distributed conflicts in program logic.

     For example: Say you change the arguments to function X defined in file A.  At the same time, someone edits file B, adding new calls to function X using the old arguments.  You are outside the realm of CVS's competence.

     Acquire the habit of reading specs and talking to your peers.

CVS does not have change control

     Change control refers to a number of things.  First of all it can mean bug-tracking, that is being able to keep a database of reported bugs and the status of each one (is it fixed?  in what release?  has the bug submitter agreed that it is fixed?).  For interfacing CVS to an external bug-tracking system, see the rcsinfo and editinfo files (see Administrative files).

     Another aspect of change control is keeping track of the fact that changes to several files were in fact changed together as one logical change.  If you check in several files in a single cvs commit operation, CVS then forgets that those files were checked in together, and the fact that they have the same log message is the only thing tying them together.  Keeping a GNU style ChangeLog can help somewhat.

     Another aspect of change control, in some systems, is the ability to keep track of the status of each change.  Some changes have been written by a developer, others have been reviewed by a second developer, and so on.  Generally, the way to do this with CVS is to generate a diff (using cvs diff or diff) and email it to someone who can then apply it using the patch utility.  This is very flexible, but depends on mechanisms outside CVS to make sure nothing falls through the cracks.

CVS is not an automated testing program

     It should be possible to enforce mandatory use of a testsuite using the commitinfo file.  I haven't heard a lot about projects trying to do that or whether there are subtle gotchas, however.

CVS does not have a builtin process model

     Some systems provide ways to ensure that changes or releases go through various steps, with various approvals as needed.  Generally, one can accomplish this with CVS but it might be a little more work. In some cases you'll want to use the commitinfo, loginfo, rcsinfo, or editinfo files, to require that certain steps be performed before cvs will allow a checkin.  Also consider whether features such as branches and tags can be used to perform tasks such as doing work in a development tree and then merging certain changes over to a stable tree only once they have been proven.

Basic concepts
**************

CVS stores all files in a centralized repository: a directory (such as /usr/local/cvsroot or user@remotehost:/usr/local/cvsroot) which is populated with a hierarchy of files and directories. (see Remote repositories for information about keeping the repository on a remote machine.)

Normally, you never access any of the files in the repository directly.  Instead, you use CVS commands to get your own copy of the files, and then work on that copy.  When you've finished a set of changes, you check (or commit) them back into the repository.

The files in the repository are organized in modules.  Each module is made up of one or more files, and can include files from several directories. A typical usage is to define one module per project.

Revision numbers
================

Each version of a file has a unique revision number.  Revision numbers look like 1.1, 1.2, 1.3.2.2 or even 1.3.2.2.4.5. A revision number always has an even number of period-separated decimal integers.  By default revision 1.1 is the first revision of a file.  Each successive revision is given a new number by increasing the rightmost number by one.  The following figure displays a few revisions, with newer revisions to the right.

            +-----+    +-----+    +-----+    +-----+    +-----+
            ! 1.1 !----! 1.2 !----! 1.3 !----! 1.4 !----! 1.5 !
            +-----+    +-----+    +-----+    +-----+    +-----+

CVS is not limited to linear development.  The revision tree can be split into branches, where each branch is a self-maintained line of development.  Changes made on one branch can easily be moved back to the main trunk.

Each branch has a branch number, consisting of an odd number of period-separated decimal integers.  The branch number is created by appending an integer to the revision number where the corresponding branch forked off.  Having branch numbers allows more than one branch to be forked off from a certain revision.

All revisions on a branch have revision numbers formed by appending an ordinal number to the branch number. The following figure illustrates branching with an example.

                                                          +-------------+
                               Branch 1.2.2.3.2 ->        ! 1.2.2.3.2.1 !
                                                        / +-------------+
                                                       /
                                                      /
                      +---------+    +---------+    +---------+    +---------+
     Branch 1.2.2 -> _! 1.2.2.1 !----! 1.2.2.2 !----! 1.2.2.3 !----! 1.2.2.4 !
                    / +---------+    +---------+    +---------+    +---------+
                   /
                  /
     +-----+    +-----+    +-----+    +-----+    +-----+
     ! 1.1 !----! 1.2 !----! 1.3 !----! 1.4 !----! 1.5 !      <- The main trunk
     +-----+    +-----+    +-----+    +-----+    +-----+
                     !
                     !
                     !   +---------+    +---------+    +---------+
     Branch 1.2.4 -> +---! 1.2.4.1 !----! 1.2.4.2 !----! 1.2.4.3 !
                         +---------+    +---------+    +---------+

The exact details of how the branch number is constructed is not something you normally need to be concerned about, but here is how it works: When CVS creates a branch number it picks the first unused even integer, starting with 2.  So when you want to create a branch from revision 6.4 it will be numbered 6.4.2.  All branch numbers ending in a zero (such as 6.4.0) are used internally by CVS (see Magic branch numbers).  The branch 1.1.1 has a special meaning.  See Tracking sources.

Versions, revisions and releases
================================

A file can have several versions, as described above. Likewise, a software product can have several versions. A software product is often given a version number such as 4.1.1.

Versions in the first sense are called revisions in this document, and versions in the second sense are called releases.  To avoid confusion, the word version is almost never used in this document.

A sample session
****************

This section describes a typical work-session using CVS.  It assumes that a repository is set up (see Repository).

Suppose you are working on a simple compiler.  The source consists of a handful of C files and a Makefile. The compiler is called tc (Trivial Compiler), and the repository is set up so that there is a module called tc.

Getting the source
==================

The first thing you must do is to get your own working copy of the source for tc.  For this, you use the checkout command:

     $ cvs checkout tc

This will create a new directory called tc and populate it with the source files.

     $ cd tc
     $ ls
     CVS         Makefile    backend.c   driver.c    frontend.c  parser.c

The CVS directory is used internally by CVS.  Normally, you should not modify or remove any of the files in it.

You start your favorite editor, hack away at backend.c, and a couple of hours later you have added an optimization pass to the compiler. A note to RCS and SCCS users: There is no need to lock the files that you want to edit.  See Multiple developers, for an explanation.

Committing your changes
=======================

When you have checked that the compiler is still compilable you decide to make a new version of backend.c.

     $ cvs commit backend.c

CVS starts an editor, to allow you to enter a log message.  You type in ``Added an optimization pass.'', save the temporary file, and exit the editor.

The environment variable $CVSEDITOR determines which editor is started.  If $CVSEDITOR is not set, then if the environment variable $EDITOR is set, it will be used. If both $CVSEDITOR and $EDITOR are not set then the editor defaults to vi.  If you want to avoid the overhead of starting an editor you can specify the log message on the command line using the -m flag instead, like this:

     $ cvs commit -m "Added an optimization pass" backend.c

Cleaning up
===========

Before you turn to other tasks you decide to remove your working copy of tc.  One acceptable way to do that is of course

     $ cd ..
     $ rm -r tc

but a better way is to use the release command (see release):

     $ cd ..
     $ cvs release -d tc
     M driver.c
     ? tc
     You have [1] altered files in this repository.
     Are you sure you want to release (and delete) module `tc': n
     ** `release' aborted by user choice.

The release command checks that all your modifications have been committed.  If history logging is enabled it also makes a note in the history file.  See history file.

When you use the -d flag with release, it also removes your working copy.

In the example above, the release command wrote a couple of lines of output.  ? tc means that the file tc is unknown to CVS. That is nothing to worry about: tc is the executable compiler, and it should not be stored in the repository.  See cvsignore, for information about how to make that warning go away. See release output, for a complete explanation of all possible output from release.

M driver.c is more serious.  It means that the file driver.c has been modified since it was checked out.

The release command always finishes by telling you how many modified files you have in your working copy of the sources, and then asks you for confirmation before deleting any files or making any note in the history file.

You decide to play it safe and answer n RET when release asks for confirmation.

Viewing differences
===================

You do not remember modifying driver.c, so you want to see what has happened to that file.

     $ cd tc
     $ cvs diff driver.c

This command runs diff to compare the version of driver.c that you checked out with your working copy.  When you see the output you remember that you added a command line option that enabled the optimization pass.  You check it in, and release the module.

     $ cvs commit -m "Added an optimization pass" driver.c
     Checking in driver.c;
     /usr/local/cvsroot/tc/driver.c,v  <--  driver.c
     new revision: 1.2; previous revision: 1.1
     done
     $ cd ..
     $ cvs release -d tc
     ? tc
     You have [0] altered files in this repository.
     Are you sure you want to release (and delete) module `tc': y

The Repository
**************

Figure 3 below shows a typical setup of a repository. Only directories are shown below.

     /usr
      |
      +--local
      |   |
      |   +--cvsroot
      |   |    |
      |   |    +--CVSROOT
               |      (administrative files)
               |
               +--gnu
               |   |
               |   +--diff
               |   |   (source code to GNU diff)
               |   |
               |   +--rcs
               |   |   (source code to RCS)
               |   |
               |   +--cvs
               |       (source code to CVS)
               |
               +--yoyodyne
                   |
                   +--tc
                   |    |
                   |    +--man
                   |    |
                   |    +--testing
                   |
                   +--(other Yoyodyne software)

There are a couple of different ways to tell CVS where to find the repository.  You can name the repository on the command line explicitly, with the -d (for "directory") option:

     cvs -d /usr/local/cvsroot checkout yoyodyne/tc

Or you can set the $CVSROOT environment variable to an absolute path to the root of the repository, /usr/local/cvsroot in this example. To set $CVSROOT, all csh and tcsh users should have this line in their .cshrc or .tcshrc files:

     setenv CVSROOT /usr/local/cvsroot

sh and bash users should instead have these lines in their .profile or .bashrc:

     CVSROOT=/usr/local/cvsroot
     export CVSROOT

A repository specified with -d will override the $CVSROOT environment variable. Once you've checked a working copy out from the repository, it will remember where its repository is (the information is recorded in the CVS/Root file in the working copy).

The -d option and the CVS/Root file both override the $CVSROOT environment variable.  If -d option differs from CVS/Root, the former is used (and specifying -d will cause CVS/Root to be updated).  Of course, for proper operation they should be two ways of referring to the same repository.

There is nothing magical about the name /usr/local/cvsroot.  You can choose to place the repository anywhere you like. See Remote repositories, to learn how the repository can be on a different machine than your working copy of the sources.

Note: For compatibility with older versions, CVS will treat any repository name that contains a colon as an indication of a remote repository (see Remote repositories).  If the name of your local repository contains a colon, you should prepend the string :local: to the pathname to tell CVS that it is, indeed, a local repository.  For example, you might use this command line under Windows NT:

     cvs -d :local:c:\src\cvsroot checkout yoyodyne/tc

The repository is split in two parts.  $CVSROOT/CVSROOT contains administrative files for CVS.  The other directories contain the actual user-defined modules.

User modules
============

       $CVSROOT
         |
         +--yoyodyne
         |   |
         |   +--tc
         |   |   |
                 +--Makefile,v
                 +--backend.c,v
                 +--driver.c,v
                 +--frontend.c,v
                 +--parser.c,v
                 +--man
                 |    |
                 |    +--tc.1,v
                 |
                 +--testing
                      |
                      +--testpgm.t,v
                      +--test2.t,v

The figure above shows the contents of the tc module inside the repository.  As you can see all file names end in ,v.  The files are history files.  They contain, among other things, enough information to recreate any revision of the file, a log of all commit messages and the user-name of the person who committed the revision.  CVS uses the facilities of RCS, a simpler version control system, to maintain these files.  For a full description of the file format, see the man page rcsfile(5).

File permissions
----------------

All ,v files are created read-only, and you should not change the permission of those files.  The directories inside the repository should be writable by the persons that have permission to modify the files in each directory.  This normally means that you must create a UNIX group (see group(5)) consisting of the persons that are to edit the files in a project, and set up the repository so that it is that group that owns the directory.

This means that you can only control access to files on a per-directory basis.

CVS tries to set up reasonable file permissions for new directories that are added inside the tree, but you must fix the permissions manually when a new directory should have different permissions than its parent directory.

Since CVS was not written to be run setuid, it is unsafe to try to run it setuid.  You cannot use the setuid features of RCS together with CVS.

The administrative files
========================

The directory $CVSROOT/CVSROOT contains some administrative files.  See Administrative files, for a complete description. You can use CVS without any of these files, but some commands work better when at least the modules file is properly set up.

The most important of these files is the modules file.  It defines all modules in the repository.  This is a sample modules file.

     CVSROOT         CVSROOT
     modules         CVSROOT modules
     cvs             gnu/cvs
     rcs             gnu/rcs
     diff            gnu/diff
     tc              yoyodyne/tc

The modules file is line oriented.  In its simplest form each line contains the name of the module, whitespace, and the directory where the module resides.  The directory is a path relative to $CVSROOT.  The last four lines in the example above are examples of such lines.

The line that defines the module called modules uses features that are not explained here. See modules, for a full explanation of all the available features.

Editing administrative files
----------------------------

You edit the administrative files in the same way that you would edit any other module.  Use cvs checkout CVSROOT to get a working copy, edit it, and commit your changes in the normal way.

It is possible to commit an erroneous administrative file.  You can often fix the error and check in a new revision, but sometimes a particularly bad error in the administrative file makes it impossible to commit new revisions.

Multiple repositories
=====================

In some situations it is a good idea to have more than one repository, for instance if you have two development groups that work on separate projects without sharing any code.  All you have to do to have several repositories is to specify the appropriate repository, using the CVSROOT environment variable, the -d option to CVS, or (once you have checked out a working directory) by simply allowing CVS to use the repository that was used to check out the working directory (see Repository).

Notwithstanding, it can be confusing to have two or more repositories.

None of the examples in this manual show multiple repositories.

Creating a repository
=====================

To set up a CVS repository, choose a directory with ample disk space available for the revision history of the source files.  It should be accessable (directly or via a networked file system) from all machines which want to use CVS in server or local mode; the client machines need not have any access to it other than via the CVS protocol.  It is not possible to use CVS to read from a repository which one only has read access to; CVS needs to be able to create lock files (see Concurrency).

To create a repository, run the cvs init command.  It will set up an empty repository in the CVS root specified in the usual way (see Repository).  For example,

     cvs -d /usr/local/cvsroot init

cvs init is careful to never overwrite any existing files in the repository, so no harm is done if you run cvs init on an already set-up repository.

cvs init will enable history logging; if you don't want that, remove the history file after running cvs init.  See history file.

Remote repositories
===================

Your working copy of the sources can be on a different machine than the repository.  Generally, using a remote repository is just like using a local one, except that the format of the repository name is:

             :method:user@hostname:/path/to/repository

The details of exactly what needs to be set up depend on how you are connecting to the server.

Connecting with rsh
-------------------

CVS uses the rsh protocol to perform these operations, so the remote user host needs to have a .rhosts file which grants access to the local user.

For example, suppose you are the user mozart on the local machine anklet.grunge.com, and the server machine is chainsaw.brickyard.com.  On chainsaw, put the following line into the file .rhosts in bach's home directory:

     anklet.grunge.com  mozart

Then test that rsh is working with

     rsh -l bach chainsaw.brickyard.com echo $PATH

Next you have to make sure that rsh will be able to find the server.  Make sure that the path which rsh printed in the above example includes the directory containing a program named cvs which is the server.  You need to set the path in .bashrc, .cshrc, etc., not .login or .profile.  Alternately, you can set the environment variable CVS_SERVER on the client machine to the filename of the server you want to use, for example /usr/local/bin/cvs-1.6.

There is no need to edit inetd.conf or start a CVS server daemon.

Continuing our example, supposing you want to access the module foo in the repository /usr/local/cvsroot/, on machine chainsaw.brickyard.com, you are ready to go:

     cvs -d :server:bach@chainsaw.brickyard.com:/usr/local/cvsroot checkout foo

(The bach@ can be omitted if the username is the same on both the local and remote hosts.)

Direct connection with password authentication
----------------------------------------------

The CVS client can also connect to the server using a password protocol.  This is particularly useful if using rsh is not feasible (for example, the server is behind a firewall), and Kerberos also is not available.

To use this method, it is necessary to make some adjustments on both the server and client sides.

Setting up the server for password authentication
.................................................

On the server side, the file /etc/inetd.conf needs to be edited so inetd knows to run the command cvs pserver when it receives a connection on the right port.  By default, the port number is 2401; it would be different if your client were compiled with CVS_AUTH_PORT defined to something else, though.

If your inetd allows raw port numbers in /etc/inetd.conf, then the following (all on a single line in inetd.conf) should be sufficient:

     2401  stream  tcp  nowait  root  /usr/local/bin/cvs
     cvs -b /usr/local/bin pserver

The -b option specifies the directory which contains the RCS binaries on the server.

If your inetd wants a symbolic service name instead of a raw port number, then put this in /etc/services:

     cvspserver      2401/tcp

and put cvspserver instead of 2401 in inetd.conf.

Once the above is taken care of, restart your inetd, or do whatever is necessary to force it to reread its initialization files.

Because the client stores and transmits passwords in cleartext (almost---see Password authentication security, for details), a separate CVS password file may be used, so people don't compromise their regular passwords when they access the repository. This file is $CVSROOT/CVSROOT/passwd (see Intro administrative files).  Its format is similar to /etc/passwd, except that it only has two fields, username and password.  For example:

     bach:ULtgRLXo7NRxs
     cwang:1sOp854gDF3DY

The password is encrypted according to the standard Unix crypt() function, so it is possible to paste in passwords directly from regular Unix passwd files.

When authenticating a password, the server first checks for the user in the CVS passwd file.  If it finds the user, it compares against that password.  If it does not find the user, or if the CVS passwd file does not exist, then the server tries to match the password using the system's user-lookup routine.  When using the CVS passwd file, the server runs under as the username specified in the the third argument in the entry, or as the first argument if there is no third argument (in this way CVS allows imaginary usernames provided the CVS passwd file indicates corresponding valid system usernames).  In any case, CVS will have no privileges which the (valid) user would not have.

Right now, the only way to put a password in the CVS passwd file is to paste it there from somewhere else.  Someday, there may be a cvs passwd command.

Using the client with password authentication
.............................................

Before connecting to the server, the client must log in with the command cvs login.  Logging in verifies a password with the server, and also records the password for later transactions with the server. The cvs login command needs to know the username, server hostname, and full repository path, and it gets this information from the repository argument or the CVSROOT environment variable.

cvs login is interactive --- it prompts for a password:

     cvs -d :pserver:bach@chainsaw.brickyard.com:/usr/local/cvsroot login
     CVS password:

The password is checked with the server; if it is correct, the login succeeds, else it fails, complaining that the password was incorrect.

Once you have logged in, you can force CVS to connect directly to the server and authenticate with the stored password:

     cvs -d :pserver:bach@chainsaw.brickyard.com:/usr/local/cvsroot checkout foo

The :pserver: is necessary because without it, CVS will assume it should use rsh to connect with the server (see Connecting via rsh). (Once you have a working copy checked out and are running CVS commands from within it, there is no longer any need to specify the repository explicitly, because CVS records it in the working copy's CVS subdirectory.)

Passwords are stored by default in the file $HOME/.cvspass.  Its format is human-readable, but don't edit it unless you know what you are doing. The passwords are not stored in cleartext, but are trivially encoded to protect them from "innocent" compromise (i.e., inadvertently being seen by a system administrator who happens to look at that file).

The CVS_PASSFILE environment variable overrides this default.  If you use this variable, make sure you set it before cvs login is run.  If you were to set it after running cvs login, then later CVS commands would be unable to look up the password for transmission to the server.

The CVS_PASSWORD environment variable overrides all stored passwords.  If it is set, CVS will use it for all password-authenticated connections.

Security considerations with password authentication
....................................................

The passwords are stored on the client side in a trivial encoding of the cleartext, and transmitted in the same encoding.  The encoding is done only to prevent inadvertent password compromises (i.e., a system administrator accidentally looking at the file), and will not prevent even a naive attacker from gaining the password.

The separate CVS password file (see Password authentication server) allows people to use a different password for repository access than for login access.  On the other hand, once a user has access to the repository, she can execute programs on the server system through a variety of means.  Thus, repository access implies fairly broad system access as well.  It might be possible to modify CVS to prevent that, but no one has done so as of this writing. Furthermore, there may be other ways in which having access to CVS allows people to gain more general access to the system; noone has done a careful audit.

In summary, anyone who gets the password gets repository access, and some measure of general system access as well.  The password is available to anyone who can sniff network packets or read a protected (i.e., user read-only) file.  If you want real security, get Kerberos.

Direct connection with kerberos
-------------------------------

The main disadvantage of using rsh is that all the data needs to pass through additional programs, so it may be slower.  So if you have kerberos installed you can connect via a direct TCP connection, authenticating with kerberos (note that the data transmitted is not encrypted by default; you must use the -x global option to request encryption).

To do this, CVS needs to be compiled with kerberos support; when configuring CVS it tries to detect whether kerberos is present or you can use the --with-krb4 flag to configure.

You need to edit inetd.conf on the server machine to run cvs kserver.  The client uses port 1999 by default; if you want to use another port specify it in the CVS_CLIENT_PORT environment variable on the client.

When you want to use CVS, get a ticket in the usual way (generally kinit); it must be a ticket which allows you to log into the server machine.  Then you are ready to go:

     cvs -d :kserver:chainsaw.brickyard.com:/user/local/cvsroot checkout foo

Previous versions of CVS would fall back to a connection via rsh; this version will not do so.

Starting a project with CVS
***************************

Since CVS 1.x is bad at renaming files and moving them between directories, the first thing you do when you start a new project should be to think through your file organization.  It is not impossible---just awkward---to rename or move files. See Moving files.

What to do next depends on the situation at hand.

Setting up the files
====================

The first step is to create the files inside the repository.  This can be done in a couple of different ways.

Creating a directory tree from a number of files
------------------------------------------------

When you begin using CVS, you will probably already have several projects that can be put under CVS control.  In these cases the easiest way is to use the import command.  An example is probably the easiest way to explain how to use it.  If the files you want to install in CVS reside in WDIR, and you want them to appear in the repository as $CVSROOT/yoyodyne/RDIR, you can do this:

     $ cd WDIR
     $ cvs import -m "Imported sources" yoyodyne/RDIR yoyo start

Unless you supply a log message with the -m flag, CVS starts an editor and prompts for a message.  The string yoyo is a vendor tag, and start is a release tag.  They may fill no purpose in this context, but since CVS requires them they must be present.  See Tracking sources, for more information about them.

You can now verify that it worked, and remove your original source directory.

     $ cd ..
     $ mv DIR DIR.orig
     $ cvs checkout yoyodyne/DIR       # Explanation below
     $ ls -R yoyodyne
     $ rm -r DIR.orig

Erasing the original sources is a good idea, to make sure that you do not accidentally edit them in DIR, bypassing CVS. Of course, it would be wise to make sure that you have a backup of the sources before you remove them.

The checkout command can either take a module name as argument (as it has done in all previous examples) or a path name relative to $CVSROOT, as it did in the example above.

It is a good idea to check that the permissions CVS sets on the directories inside $CVSROOT are reasonable, and that they belong to the proper groups.  See File permissions.

If some of the files you want to import are binary, you may want to use the wrappers features to specify which files are binary and which are not.  See Wrappers.

Creating Files From Other Version Control Systems
-------------------------------------------------

If you have a project which you are maintaining with another version control system, such as RCS, you may wish to put the files from that project into CVS, and preserve the revision history of the files.

From RCS
     If you have been using RCS, find the RCS files---usually a file named foo.c will have its RCS file in RCS/foo.c,v (but it could be other places; consult the RCS documentation for details).  Then create the appropriate directories in CVS if they do not already exist.  Then copy the files into the appropriate directories in the CVS repository (the name in the repository must be the name of the source file with ,v added; the files go directly in the appopriate directory of the repository, not in an RCS subdirectory).  This is one of the few times when it is a good idea to access the CVS repository directly, rather than using CVS commands.  Then you are ready to check out a new working directory.

From another version control system
     Many version control systems have the ability to export RCS files in the standard format.  If yours does, export the RCS files and then follow the above instructions.

From SCCS
     There is a script in the contrib directory of the CVS source distribution called sccs2rcs which converts SCCS files to RCS files. Note: you must run it on a machine which has both SCCS and RCS installed, and like everything else in contrib it is unsupported (your mileage may vary).

Creating a directory tree from scratch
--------------------------------------

For a new project, the easiest thing to do is probably to create an empty directory structure, like this:

     $ mkdir tc
     $ mkdir tc/man
     $ mkdir tc/testing

After that, you use the import command to create the corresponding (empty) directory structure inside the repository:

     $ cd tc
     $ cvs import -m "Created directory structure" yoyodyne/DIR yoyo start

Then, use add to add files (and new directories) as they appear.

Check that the permissions CVS sets on the directories inside $CVSROOT are reasonable.

Defining the module
===================

The next step is to define the module in the modules file.  This is not strictly necessary, but modules can be convenient in grouping together related files and directories.

In simple cases these steps are sufficient to define a module.

 1. Get a working copy of the modules file.

          $ cvs checkout modules
          $ cd modules

 2. Edit the file and insert a line that defines the module.  See Intro administrative files, for an introduction.  See modules, for a full description of the modules file.  You can use the following line to define the module tc:

          tc   yoyodyne/tc

 3. Commit your changes to the modules file.

          $ cvs commit -m "Added the tc module." modules

 4. Release the modules module.

          $ cd ..
          $ cvs release -d modules

Multiple developers
*******************

When more than one person works on a software project things often get complicated.  Often, two people try to edit the same file simultaneously.  Some other version control systems (including RCS and SCCS) try to solve that particular problem by introducing file locking, so that only one person can edit each file at a time.  Unfortunately, file locking 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.

CVS does not use file locking.  Instead, it allows many people to edit their own working copy of a file simultaneously.  The first person that commits his changes has no automatic way of knowing that another has started to edit it.  Others will get an error message when they try to commit the file.  They must then use CVS commands to bring their working copy up to date with the repository revision.  This process is almost automatic, and explained in this chapter.

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.  It is often useful to inform the group of commits you have done.  CVS has several ways of automating that process.  See Informing others. See Revision management, for more tips on how to use CVS.

File status
===========

After you have checked out a file out from CVS, it is in one of these four states:

Up-to-date
     The file is identical with the latest revision in the repository.

Locally modified
     You have edited the file, and not yet committed your changes.

Needing update
     Someone else has committed a newer revision to the repository.

Needing merge
     Someone else have committed a newer revision to the repository, and you have also made modifications to the file.

You can use the status command to find out the status of a given file.  See status.

Bringing a file up to date
==========================

When you want to update or merge a file, use the update command.  For files that are not up to date this is roughly equivalent to a checkout command: the newest revision of the file is extracted from the repository and put in your working copy of the module.

Your modifications to a file are never lost when you use update.  If no newer revision exists, running update has no effect.  If you have edited the file, and a newer revision is available, CVS will merge all changes into your working copy.

For instance, imagine that you checked out revision 1.4 and started editing it.  In the meantime someone else committed revision 1.5, and shortly after that revision 1.6.  If you run update on the file now, CVS will incorporate all changes between revision 1.4 and 1.6 into your file.

If any of the changes between 1.4 and 1.6 were made too close to any of the changes you have made, an overlap occurs.  In such cases a warning is printed, and the resulting file includes both versions of the lines that overlap, delimited by special markers. See update, for a complete description of the update command.

Conflicts example
=================

Suppose revision 1.4 of driver.c contains this:

     #include <stdio.h>

     void main()
     {
         parse();
         if (nerr == 0)
             gencode();
         else
             fprintf(stderr, "No code generated.\n");
         exit(nerr == 0 ? 0 : 1);
     }

Revision 1.6 of driver.c contains this:

     #include <stdio.h>

     int main(int argc,
              char **argv)
     {
         parse();
         if (argc != 1)
         {
             fprintf(stderr, "tc: No args expected.\n");
             exit(1);
         }
         if (nerr == 0)
             gencode();
         else
             fprintf(stderr, "No code generated.\n");
         exit(!!nerr);
     }

Your working copy of driver.c, based on revision 1.4, contains this before you run cvs update:

     #include <stdlib.h>
     #include <stdio.h>

     void main()
     {
         init_scanner();
         parse();
         if (nerr == 0)
             gencode();
         else
             fprintf(stderr, "No code generated.\n");
         exit(nerr == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
     }

You run cvs update:

     $ cvs update driver.c
     RCS file: /usr/local/cvsroot/yoyodyne/tc/driver.c,v
     retrieving revision 1.4
     retrieving revision 1.6
     Merging differences between 1.4 and 1.6 into driver.c
     rcsmerge warning: overlaps during merge
     cvs update: conflicts found in driver.c
     C driver.c

CVS tells you that there were some conflicts. Your original working file is saved unmodified in .#driver.c.1.4.  The new version of driver.c contains this:

     #include <stdlib.h>
     #include <stdio.h>

     int main(int argc,
              char **argv)
     {
         init_scanner();
         parse();
         if (argc != 1)
         {
             fprintf(stderr, "tc: No args expected.\n");
             exit(1);
         }
         if (nerr == 0)
             gencode();
         else
             fprintf(stderr, "No code generated.\n");
      <<<<<<< driver.c
         exit(nerr == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
      =======
         exit(!!nerr);
      >>>>>>> 1.6
     }

Note how all non-overlapping modifications are incorporated in your working copy, and that the overlapping section is clearly marked with <<<<<<<, ======= and >>>>>>>.

You resolve the conflict by editing the file, removing the markers and the erroneous line.  Suppose you end up with this file:

     #include <stdlib.h>
     #include <stdio.h>

     int main(int argc,
              char **argv)
     {
         init_scanner();
         parse();
         if (argc != 1)
         {
             fprintf(stderr, "tc: No args expected.\n");
             exit(1);
         }
         if (nerr == 0)
             gencode();
         else
             fprintf(stderr, "No code generated.\n");
         exit(nerr == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
     }

You can now go ahead and commit this as revision 1.7.

     $ cvs commit -m "Initialize scanner. Use symbolic exit values." driver.c
     Checking in driver.c;
     /usr/local/cvsroot/yoyodyne/tc/driver.c,v  <--  driver.c
     new revision: 1.7; previous revision: 1.6
     done

If you use release 1.04 or later of pcl-cvs (a GNU Emacs front-end for CVS) you can use an Emacs package called emerge to help you resolve conflicts. See the documentation for pcl-cvs.

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.  See modules. See 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.

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 for and remove files starting with #cvs.tfl, #cvs.rfl, or #cvs.wfl from the repository.

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--a way to prevent other developers from working on a particular file.

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.

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.

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 [-l] 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.

     If FILES is omitted, it defaults to the current directory.

 -- Command: cvs watch off [-l] files ...

     Do not provide notification about work on FILES.  CVS will create working copies of FILES read-write.

     The FILES and -l arguments are processed as for cvs watch on.

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] [-l] 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 -l option are processed as for the cvs watch commands.

 -- Command: cvs watch remove [-a action] [-l] 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 (see Intro administrative files).  This file follows the usual conventions for administrative files (see 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).

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.

 -- 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 unedited or committed.  If the user does not wish to receive notifications, she should specify -a none.

     The FILES and -l option are processed as for the cvs watch commands.

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 [-l] 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 -l option are processed as for the cvs watch commands.

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.

Information about who is watching and editing
---------------------------------------------

 -- Command: cvs watchers [-l] 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 -l arguments are processed as for the cvs watch commands.

 -- Command: cvs editors [-l] 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 -l arguments are processed as for the cvs watch commands.

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

     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.

Branches
********

So far, all revisions shown in this manual have been on the main trunk of the revision tree, i.e., all revision numbers have been of the form X.Y.  One useful feature, especially when maintaining several releases of a software product at once, is the ability to make branches on the revision tree.  Tags, symbolic names for revisions, will also be introduced in this chapter.

Tags--Symbolic revisions
========================

The revision numbers live a life of their own.  They need not have anything at all to do with the release numbers of your software product.  Depending on how you use CVS the revision numbers might change several times between two releases.  As an example, some of the source files that make up RCS 5.6 have the following revision numbers:

     ci.c            5.21
     co.c            5.9
     ident.c         5.3
     rcs.c           5.12
     rcsbase.h       5.11
     rcsdiff.c       5.10
     rcsedit.c       5.11
     rcsfcmp.c       5.9
     rcsgen.c        5.10
     rcslex.c        5.11
     rcsmap.c        5.2
     rcsutil.c       5.10

You can use the tag command to give a symbolic name to a certain revision of a file.  You can use the -v flag to the status command to see all tags that a file has, and which revision numbers they represent.  Tag names can contain uppercase and lowercase letters, digits, -, and _.  The two tag names BASE and HEAD are reserved for use by CVS.  It is expected that future names which are special to CVS will contain characters such as % or =, rather than being named analogously to BASE and HEAD, to avoid conflicts with actual tag names.

The following example shows how you can add a tag to a file.  The commands must be issued inside your working copy of the module.  That is, you should issue the command in the directory where backend.c resides.

     $ cvs tag release-0-4 backend.c
     T backend.c
     $ cvs status -v backend.c
     ===================================================================
     File: backend.c         Status: Up-to-date

         Version:            1.4     Tue Dec  1 14:39:01 1992
         RCS Version:        1.4     /usr/local/cvsroot/yoyodyne/tc/backend.c,v
         Sticky Tag:         (none)
         Sticky Date:        (none)
         Sticky Options:     (none)

         Existing Tags:
             release-0-4                     (revision: 1.4)

There is seldom reason to tag a file in isolation.  A more common use is to tag all the files that constitute a module with the same tag at strategic points in the development life-cycle, such as when a release is made.

     $ cvs tag release-1-0 .
     cvs tag: Tagging .
     T Makefile
     T backend.c
     T driver.c
     T frontend.c
     T parser.c

(When you give CVS a directory as argument, it generally applies the operation to all the files in that directory, and (recursively), to any subdirectories that it may contain.  See Recursive behavior.)

The checkout command has a flag, -r, that lets you check out a certain revision of a module.  This flag makes it easy to retrieve the sources that make up release 1.0 of the module tc at any time in the future:

     $ cvs checkout -r release-1-0 tc

This is useful, for instance, if someone claims that there is a bug in that release, but you cannot find the bug in the current working copy.

You can also check out a module as it was at any given date. See checkout options.

When you tag more than one file with the same tag you can think about the tag as "a curve drawn through a matrix of filename vs. revision number."  Say we have 5 files with the following revisions:

             file1   file2   file3   file4   file5

             1.1     1.1     1.1     1.1  /--1.1*      <-*-  TAG
             1.2*-   1.2     1.2    -1.2*-
             1.3  \- 1.3*-   1.3   / 1.3
             1.4          \  1.4  /  1.4
                           \-1.5*-   1.5
                             1.6

At some time in the past, the * versions were tagged. You can think of the tag as a handle attached to the curve drawn through the tagged revisions.  When you pull on the handle, you get all the tagged revisions.  Another way to look at it is that you "sight" through a set of revisions that is "flat" along the tagged revisions, like this:

             file1   file2   file3   file4   file5

                             1.1
                             1.2
                     1.1     1.3                       _
             1.1     1.2     1.4     1.1              /
             1.2*----1.3*----1.5*----1.2*----1.1     (--- <--- Look here
             1.3             1.6     1.3              \_
             1.4                     1.4
                                     1.5

What branches are good for
==========================

Suppose that release 1.0 of tc has been made.  You are continuing to develop tc, planning to create release 1.1 in a couple of months.  After a while your customers start to complain about a fatal bug.  You check out release 1.0 (see Tags) and find the bug (which turns out to have a trivial fix).  However, the current revision of the sources are in a state of flux and are not expected to be stable for at least another month.  There is no way to make a bugfix release based on the newest sources.

The thing to do in a situation like this is to create a branch on the revision trees for all the files that make up release 1.0 of tc.  You can then make modifications to the branch without disturbing the main trunk.  When the modifications are finished you can select to either incorporate them on the main trunk, or leave them on the branch.

Creating a branch
=================

The rtag command can be used to create a branch. The rtag command is much like tag, but it does not require that you have a working copy of the module.  See rtag.  (You can also use the tag command; see tag).

     $ cvs rtag -b -r release-1-0 release-1-0-patches tc

The -b flag makes rtag create a branch (rather than just a symbolic revision name).  -r release-1-0 says that this branch should be rooted at the node (in the revision tree) that corresponds to the tag release-1-0.  Note that the numeric revision number that matches release-1-0 will probably be different from file to file.  The name of the new branch is release-1-0-patches, and the module affected is tc.

To fix the problem in release 1.0, you need a working copy of the branch you just created.

     $ cvs checkout -r release-1-0-patches tc
     $ cvs status -v driver.c backend.c
     ===================================================================
     File: driver.c          Status: Up-to-date

         Version:            1.7     Sat Dec  5 18:25:54 1992
         RCS Version:        1.7     /usr/local/cvsroot/yoyodyne/tc/driver.c,v
         Sticky Tag:         release-1-0-patches (branch: 1.7.2)
         Sticky Date:        (none)
         Sticky Options:     (none)

         Existing Tags:
             release-1-0-patches             (branch: 1.7.2)
             release-1-0                     (revision: 1.7)

     ===================================================================
     File: backend.c         Status: Up-to-date

         Version:            1.4     Tue Dec  1 14:39:01 1992
         RCS Version:        1.4     /usr/local/cvsroot/yoyodyne/tc/backend.c,v
         Sticky Tag:         release-1-0-patches (branch: 1.4.2)
         Sticky Date:        (none)
         Sticky Options:     (none)

         Existing Tags:
             release-1-0-patches             (branch: 1.4.2)
             release-1-0                     (revision: 1.4)
             release-0-4                     (revision: 1.4)

As the output from the status command shows the branch number is created by adding a digit at the tail of the revision number it is based on.  (If release-1-0 corresponds to revision 1.4, the branch's revision number will be 1.4.2.  For obscure reasons CVS always gives branches even numbers, starting at 2. See Revision numbers.).

Sticky tags
===========

The -r release-1-0-patches flag that was given to checkout in the previous example is sticky, that is, it will apply to subsequent commands in this directory.  If you commit any modifications, they are committed on the branch.  You can later merge the modifications into the main trunk.  See Merging.

You can use the status command to see what sticky tags or dates are set:

     $ vi driver.c   # Fix the bugs
     $ cvs commit -m "Fixed initialization bug" driver.c
     Checking in driver.c;
     /usr/local/cvsroot/yoyodyne/tc/driver.c,v  <--  driver.c
     new revision: 1.7.2.1; previous revision: 1.7
     done
     $ cvs status -v driver.c
     ===================================================================
     File: driver.c          Status: Up-to-date

         Version:            1.7.2.1 Sat Dec  5 19:35:03 1992
         RCS Version:        1.7.2.1 /usr/local/cvsroot/yoyodyne/tc/driver.c,v
         Sticky Tag:         release-1-0-patches (branch: 1.7.2)
         Sticky Date:        (none)
         Sticky Options:     (none)

         Existing Tags:
             release-1-0-patches             (branch: 1.7.2)
             release-1-0                     (revision: 1.7)

The sticky tags will remain on your working files until you delete them with cvs update -A.  The -A option retrieves the version of the file from the head of the trunk, and forgets any sticky tags, dates, or options.

Sticky tags are not just for branches.  For example, suppose that you want to avoid updating your working directory, to isolate yourself from possibly destabilizing changes other people are making.  You can, of course, just refrain from running cvs update.  But if you want to avoid updating only a portion of a larger tree, then sticky tags can help. If you check out a certain revision (such as 1.4) it will become sticky.  Subsequent cvs update will not retrieve the latest revision until you reset the tag with cvs update -A.  Likewise, use of the -D option to update or checkout sets a sticky date, which, similarly, causes that date to be used for future retrievals.

Many times you will want to retrieve an old version of a file without setting a sticky tag.  The way to do that is with the -p option to checkout or update, which sends the contents of the file to standard output.  For example, suppose you have a file named file1 which existed as revision 1.1, and you then removed it (thus adding a dead revision 1.2). Now suppose you want to add it again, with the same contents it had previously.  Here is how to do it:

     $ cvs update -p -r 1.1 file1 >file1
     ===================================================================
     Checking out file1
     RCS:  /tmp/cvs-sanity/cvsroot/first-dir/Attic/file1,v
     VERS: 1.1
     ***************
     $ cvs add file1
     cvs add: re-adding file file1 (in place of dead revision 1.2)
     cvs add: use 'cvs commit' to add this file permanently
     $ cvs commit -m test
     Checking in file1;
     /tmp/cvs-sanity/cvsroot/first-dir/file1,v  <--  file1
     new revision: 1.3; previous revision: 1.2
     done
     $

Merging
*******

You can include the changes made between any two revisions into your working copy, by merging. You can then commit that revision, and thus effectively copy the changes onto another branch.

Merging an entire branch
========================

You can merge changes made on a branch into your working copy by giving the -j BRANCH flag to the update command.  With one -j BRANCH option it merges the changes made between the point where the branch forked and newest revision on that branch (into your working copy).

The -j stands for ``join''.

Consider this revision tree:

     +-----+    +-----+    +-----+    +-----+
     ! 1.1 !----! 1.2 !----! 1.3 !----! 1.4 !      <- The main trunk
     +-----+    +-----+    +-----+    +-----+
                     !
                     !
                     !   +---------+    +---------+
     Branch R1fix -> +---! 1.2.2.1 !----! 1.2.2.2 !
                         +---------+    +---------+

The branch 1.2.2 has been given the tag (symbolic name) R1fix.  The following example assumes that the module mod contains only one file, m.c.

     $ cvs checkout mod               # Retrieve the latest revision, 1.4

     $ cvs update -j R1fix m.c        # Merge all changes made on the branch,
                                      # i.e. the changes between revision 1.2
                                      # and 1.2.2.2, into your working copy
                                      # of the file.

     $ cvs commit -m "Included R1fix" # Create revision 1.5.

A conflict can result from a merge operation.  If that happens, you should resolve it before committing the new revision.  See Conflicts example.

The checkout command also supports the -j BRANCH flag.  The same effect as above could be achieved with this:

     $ cvs checkout -j R1fix mod
     $ cvs commit -m "Included R1fix"

Merging from a branch several times
===================================

Continuing our example, the revision tree now looks like this:

     +-----+    +-----+    +-----+    +-----+    +-----+
     ! 1.1 !----! 1.2 !----! 1.3 !----! 1.4 !----! 1.5 !      <- The main trunk
     +-----+    +-----+    +-----+    +-----+    +-----+
                     !                           *
                     !                          *
                     !   +---------+    +---------+
     Branch R1fix -> +---! 1.2.2.1 !----! 1.2.2.2 !
                         +---------+    +---------+

where the starred line represents the merge from the R1fix branch to the main trunk, as just discussed.

Now suppose that development continues on the R1fix branch:

     +-----+    +-----+    +-----+    +-----+    +-----+
     ! 1.1 !----! 1.2 !----! 1.3 !----! 1.4 !----! 1.5 !      <- The main trunk
     +-----+    +-----+    +-----+    +-----+    +-----+
                     !                           *
                     !                          *
                     !   +---------+    +---------+    +---------+
     Branch R1fix -> +---! 1.2.2.1 !----! 1.2.2.2 !----! 1.2.2.3 !
                         +---------+    +---------+    +---------+

and then you want to merge those new changes onto the main trunk.  If you just use the cvs update -j R1fix m.c command again, CVS will attempt to merge again the changes which you have already merged, which can have undesirable side effects.

So instead you need to specify that you only want to merge the changes on the branch which have not yet been merged into the trunk.  To do that you specify two -j options, and CVS merges the changes from the first revision to the second revision.  For example, in this case the simplest way would be

     cvs update -j 1.2.2.2 -j R1fix m.c    # Merge changes from 1.2.2.2 to the
                                           # head of the R1fix branch

The problem with this is that you need to specify the 1.2.2.2 revision manually.  A slightly better approach might be to use the date the last merge was done:

     cvs update -j R1fix:yesterday -j R1fix m.c

Better yet, tag the R1fix branch after every merge into the trunk, and then use that tag for subsequent merges:

     cvs update -j merged_from_R1fix_to_trunk -j R1fix m.c

Merging differences between any two revisions
=============================================

With two -j REVISION flags, the update (and checkout) command can merge the differences between any two revisions into your working file.

     $ cvs update -j 1.5 -j 1.3 backend.c

will remove all changes made between revision 1.3 and 1.5.  Note the order of the revisions!

If you try to use this option when operating on multiple files, remember that the numeric revisions will probably be very different between the various files that make up a module.  You almost always use symbolic tags rather than revision numbers when operating on multiple files.

Recursive behavior
******************

Almost all of the subcommands of CVS work recursively when you specify a directory as an argument.  For instance, consider this directory structure:

           $HOME
             |
             +--tc
             |   |
                 +--CVS
                 |      (internal CVS files)
                 +--Makefile
                 +--backend.c
                 +--driver.c
                 +--frontend.c
                 +--parser.c
                 +--man
                 |    |
                 |    +--CVS
                 |    |  (internal CVS files)
                 |    +--tc.1
                 |
                 +--testing
                      |
                      +--CVS
                      |  (internal CVS files)
                      +--testpgm.t
                      +--test2.t

If tc is the current working directory, the following is true:

  * cvs update testing is equivalent to cvs update testing/testpgm.t testing/test2.t

  * cvs update testing man updates all files in the subdirectories

  * cvs update . or just cvs update updates all files in the tc module

If no arguments are given to update it will update all files in the current working directory and all its subdirectories.  In other words, . is a default argument to update.  This is also true for most of the CVS subcommands, not only the update command.

The recursive behavior of the CVS subcommands can be turned off with the -l option.

     $ cvs update -l         # Don't update files in subdirectories

Adding files to a module
************************

To add a new file to a module, follow these steps.

  * You must have a working copy of the module. See Getting the source.

  * Create the new file inside your working copy of the module.

  * Use cvs add FILENAME to tell CVS that you want to version control the file.

  * Use cvs commit FILENAME to actually check in the file into the repository.  Other developers cannot see the file until you perform this step.

  * If the file contains binary data it might be necessary to change the default keyword substitution. See Keyword substitution.  See admin examples.

You can also use the add command to add a new directory inside a module.

Unlike most other commands, the add command is not recursive.  You cannot even type cvs add foo/bar!  Instead, you have to

     $ cd foo
     $ cvs add bar

See add, for a more complete description of the add command.

Removing files from a module
****************************

Modules change.  New files are added, and old files disappear.  Still, you want to be able to retrieve an exact copy of old releases of the module.

Here is what you can do to remove a file from a module, but remain able to retrieve old revisions:

  * Make sure that you have not made any uncommitted modifications to the file.  See Viewing differences, for one way to do that.  You can also use the status or update command.  If you remove the file without committing your changes, you will of course not be able to retrieve the file as it was immediately before you deleted it.

  * Remove the file from your working copy of the module. You can for instance use rm.

  * Use cvs remove FILENAME to tell CVS that you really want to delete the file.

  * Use cvs commit FILENAME to actually perform the removal of the file from the repository.

When you commit the removal of the file, CVS records the fact that the file no longer exists.  It is possible for a file to exist on only some branches and not on others, or to re-add another file with the same name later.  CVS will correctly create or not create the file, based on the -r and -D options specified to checkout or update.

 -- Command: cvs remove [-lR] files ...

     Schedule file(s) to be removed from the repository (files which have not already been removed from the working directory are not processed).  This command does not actually remove the file from the repository until you commit the removal.  The -R option (the default) specifies that it will recurse into subdirectories; -l specifies that it will not.

Here is an example of removing several files:

     $ cd test
     $ rm ?.c
     $ cvs remove
     cvs remove: Removing .
     cvs remove: scheduling a.c for removal
     cvs remove: scheduling b.c for removal
     cvs remove: use 'cvs commit' to remove these files permanently
     $ cvs ci -m "Removed unneeded files"
     cvs commit: Examining .
     cvs commit: Committing .

If you change your mind you can easily resurrect the file before you commit it, using the add command.

     $ ls
     CVS   ja.h  oj.c
     $ rm oj.c
     $ cvs remove oj.c
     cvs remove: scheduling oj.c for removal
     cvs remove: use 'cvs commit' to remove this file permanently
     $ cvs add oj.c
     U oj.c
     cvs add: oj.c, version 1.1.1.1, resurrected

If you realize your mistake before you run the remove command you can use update to resurrect the file:

     $ rm oj.c
     $ cvs update oj.c
     cvs update: warning: oj.c was lost
     U oj.c

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.  After a successful import 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.

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---see import options.).  The release tags are symbolic names for a particular release, such as FSF_0_04.

Suppose you use wdiff (a variant of diff that ignores changes that only involve whitespace), 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:

     $ tar xfz wdiff-0.04.tar.gz
     $ 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.

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 (see 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.

How to handle binary files with cvs import
==========================================

Use the -k wrapper option to tell import which files are binary.  See Wrappers.

Moving and renaming files
*************************

Moving files to a different directory or renaming them is not difficult, but some of the ways in which this works may be non-obvious.  (Moving or renaming a directory is even harder.  See Moving directories.).

The examples below assume that the file OLD is renamed to NEW.

The Normal way to Rename
========================

The normal way to move a file is to copy OLD to NEW, and then issue the normal CVS commands to remove OLD from the repository, and add NEW to it.  (Both OLD and NEW could contain relative paths, for example foo/bar.c).

     $ mv OLD NEW
     $ cvs remove OLD
     $ cvs add NEW
     $ cvs commit -m "Renamed OLD to NEW" OLD NEW

This is the simplest way to move a file, it is not error-prone, and it preserves the history of what was done.  Note that to access the history of the file you must specify the old or the new name, depending on what portion of the history you are accessing.  For example, cvs log OLD will give the log up until the time of the rename.

When NEW is committed its revision numbers will start at 1.0 again, so if that bothers you, use the -r rev option to commit (see commit options)

Moving the history file
=======================

This method is more dangerous, since it involves moving files inside the repository.  Read this entire section before trying it out!

     $ cd $CVSROOT/MODULE
     $ mv OLD,v NEW,v

Advantages:

  * The log of changes is maintained intact.

  * The revision numbers are not affected.

Disadvantages:

  * Old releases of the module cannot easily be fetched from the repository.  (The file will show up as NEW even in revisions from the time before it was renamed).

  * There is no log information of when the file was renamed.

  * Nasty things might happen if someone accesses the history file while you are moving it.  Make sure no one else runs any of the CVS commands while you move it.

Copying the history file
========================

This way also involves direct modifications to the repository.  It is safe, but not without drawbacks.

     # Copy the RCS file inside the repository
     $ cd $CVSROOT/MODULE
     $ cp OLD,v NEW,v
     # Remove the old file
     $ cd ~/MODULE
     $ rm OLD
     $ cvs remove OLD
     $ cvs commit OLD
     # Remove all tags from NEW
     $ cvs update NEW
     $ cvs log NEW             # Remember the tag names
     $ cvs tag -d TAG1
     $ cvs tag -d TAG2
     ...

By removing the tags you will be able to check out old revisions of the module.

Advantages:

  * Checking out old revisions works correctly, as long as you use -rTAG and not -DDATE to retrieve the revisions.

  * The log of changes is maintained intact.

  * The revision numbers are not affected.

Disadvantages:

  * You cannot easily see the history of the file across the rename.

  * Unless you use the -r rev (see commit options) flag when NEW is committed its revision numbers will start at 1.0 again.

Moving and renaming directories
*******************************

If you want to be able to retrieve old versions of the module, you must move each file in the directory with the CVS commands.  See Outside.  The old, empty directory will remain inside the repository, but it will not appear in your workspace when you check out the module in the future.

If you really want to rename or delete a directory, you can do it like this:

 1. Inform everyone who has a copy of the module that the directory will be renamed.  They should commit all their changes, and remove their working copies of the module, before you take the steps below.

 2. Rename the directory inside the repository.

          $ cd $CVSROOT/MODULE
          $ mv OLD-DIR NEW-DIR

 3. Fix the CVS administrative files, if necessary (for instance if you renamed an entire module).

 4. Tell everyone that they can check out the module and continue working.

If someone had a working copy of the module the CVS commands will cease to work for him, until he removes the directory that disappeared inside the repository.

It is almost always better to move the files in the directory instead of moving the directory.  If you move the directory you are unlikely to be able to retrieve old releases correctly, since they probably depend on the name of the directories.

History browsing
****************

Once you have used CVS to store a version control history---what files have changed when, how, and by whom, there are a variety of mechanisms for looking through the history.

Log messages
============

Whenever you commit a file you specify a log message.

To look through the log messages which have been specified for every revision which has been committed, use the cvs log command (see log).

The history database
====================

You can use the history file (see history file) to log various CVS actions.  To retrieve the information from the history file, use the cvs history command (see history).

User-defined logging
====================

You can customize CVS to log various kinds of actions, in whatever manner you choose.  These mechanisms operate by executing a script at various times.  The script might append a message to a file listing the information and the programmer who created it, or send mail to a group of developers, or, perhaps, post a message to a particular newsgroup.  To log commits, use the loginfo file (see loginfo). To log commits, checkouts, exports, and tags, respectively, you can also use the -i, -o, -e, and -t options in the modules file.  For a more flexible way of giving notifications to various users, which requires less in the way of keeping centralized scripts up to date, use the cvs watch add command (see Getting Notified); this command is useful even if you are not using cvs watch on.

The taginfo file defines programs to execute when someone executes a tag or rtag command.  The taginfo file has the standard form for administrative files (see Administrative files), where each line is a regular expression followed by a command to execute.  The arguments passed to the command are, in order, the TAGNAME, OPERATION (add for tag, mov for tag -F, and del for tag -d), REPOSITORY, and any remaining are pairs of FILENAME REVISION.  A non-zero exit of the filter program will cause the tag to be aborted.

Annotate command
================

 -- Command: cvs annotate [-lf] [-r rev|-D date] files ...

     For each file in FILES, print the head revision of the trunk, together with information on the last modification for each line.  For example:

          $ cvs annotate ssfile
          Annotations for ssfile
          ***************
          1.1          (mary     27-Mar-96): ssfile line 1
          1.2          (joe      28-Mar-96): ssfile line 2

     The file ssfile currently contains two lines. The ssfile line 1 line was checked in by mary on March 27.  Then, on March 28, joe added a line ssfile line 2, without modifying the ssfile line 1 line.  This report doesn't tell you anything about lines which have been deleted or replaced; you need to use cvs diff for that (see diff).

These standard options are available with annotate (see Common options, for a complete description of them):

-D DATE
     Annotate the most recent revision no later than DATE.

-f
     Only useful with the -D DATE or -r TAG flags.  If no matching revision is found, annotate the most recent revision (instead of ignoring the file).

-l
     Local; run only in current working directory.  See Recursive behavior.

-r TAG
     Annotate revision TAG.

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.

RCS uses 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.

RCS Keywords
============

This is a list of the keywords that RCS currently (in release 5.6.0.1) supports:

$Author$
     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 a comment leader which RCS guesses from the file name extension. It can be changed with cvs admin -c. See admin options.  This keyword is useful for accumulating a complete change log in a source file, but for several reasons it can be problematic. See 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 admin options.

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 $Id$ string in the C source code.  This example shows the first few lines of a typical file, after keyword substitution has been performed:

     static char *rcsid="$Id: samp.c,v 1.5 1993/10/19 14:57:32 ceder Exp $";
     /* The following lines will prevent gcc version 2.X
        from issuing an "unused variable" warning. */
     #if __GNUC__ == 2
     #define USE(var) static void * use_##var = (&use_##var, (void *) &var)
     USE (rcsid);
     #endif

Even though a clever optimizing compiler could remove the unused variable rcsid, most compilers tend to include the string in the binary.  Some compilers have a #pragma directive to include literal text in the binary.

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 $";

Avoiding substitution
=====================

Keyword substitution has its disadvantages.  Sometimes you might want the literal text string $Author$ to appear inside a file without RCS 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 (see Substitution modes) to turn off keyword substitution entirely.

In many cases you can avoid using RCS 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.

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 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 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---see export.  But be aware that doesn't handle an export containing binary files correctly.

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 RCS 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.

Handling binary files
*********************

There are two issues with using CVS to store binary files.  The first is that CVS by default convert 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 example, carriage return followed by line feed for Windows NT).

The second is that a binary file might happen to contain data which looks like a keyword (see Keyword substitution), so keyword expansion must be turned off.

The -kb option available with some CVS commands insures that neither line ending conversion nor keyword expansion will be done.  If you are using an old version of RCS without this option, and you are using an operating system, such as unix, which terminates lines with linefeeds only, you can use -ko instead; if you are on another operating system, upgrade to a version of RCS, such as 5.7 or later, which supports -kb.

Here is an example of how you can create a new file using the -kb flag:

     $ echo '$Id$' > kotest
     $ cvs add -kb -m"A test file" kotest
     $ cvs ci -m"First checkin; contains a keyword" kotest

If a file accidentally gets added without -kb, one can use the cvs admin command to recover. For example:

     $ echo '$Id$' > kotest
     $ cvs add -m"A test file" kotest
     $ cvs ci -m"First checkin; contains a keyword" kotest
     $ cvs admin -kb kotest
     $ cvs update -A kotest
     $ cvs commit -m "make it binary" kotest  # For non-unix systems

When you check in the file kotest the keywords are expanded.  (Try the above example, and do a cat kotest after every command).  The cvs admin -kb command sets the default keyword substitution method for this file, but it does not alter the working copy of the file that you have.  The easiest way to get the unexpanded version of kotest is cvs update -A.  If you need to cope with line endings (that is, you are using a CVS client on a non-unix system), then you need to check in a new copy of the file, as shown by the cvs commit command above.

However, in using cvs admin -k to change the keyword expansion, be aware that the keyword expansion mode is not version controlled.  This means that, for example, that if you have a text file in old releases, and a binary file with the same name in new releases, CVS provides no way to check out the file in text or binary mode depending on what version you are checking out.  There is no good workaround for this problem.

You can also set a default for whether cvs add and cvs import treat a file as binary based on its name; for example you could say that files who names end in .exe are binary.  See Wrappers.

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.

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 (see 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.

Reference manual for CVS commands
*********************************

This appendix describes how to invoke CVS, and describes in detail those subcommands of CVS which are not fully described elsewhere.  To look up a particular subcommand, see Index.

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.

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
     co -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 (see Global options).  For example the following line in .cvsrc

     cvs -z6

causes CVS to use compression level 6

Global options
==============

The available cvs_options (that are given to the left of cvs_command) are:

-b BINDIR
     Use BINDIR as the directory where RCS programs are located.  Overrides the setting of the $RCSBIN environment variable and any precompiled directory.  This parameter should be specified as an absolute pathname.

-d CVS_ROOT_DIRECTORY
     Use CVS_ROOT_DIRECTORY as the root directory pathname of the repository.  Overrides the setting of the $CVSROOT environment variable.  See Repository.

-e EDITOR
     Use EDITOR to enter revision log information.  Overrides the setting of the $CVSEDITOR and $EDITOR environment variables.

-f
     Do not read the ~/.cvsrc file.  This option is most often used because of the non-orthogonality of the CVS option set.  For example, the cvs log option -N (turn off display of tag names) does not have a corresponding option to turn the display on.  So if you have -N in the ~/.cvsrc entry for log, you may need to use -f to show the tag names.

-H
     Display usage information about the specified cvs_command (but do not actually execute the command).  If you don't specify a command name, cvs -H displays a summary of all the commands available.

-l
     Do not log the cvs_command in the command history (but execute it anyway).  See history, for information on command history.

-n
     Do not change any files.  Attempt to execute the cvs_command, but only to issue reports; do not remove, update, or merge any existing files, or create any new files.

-Q
     Cause the command to be really quiet; the command will only generate output for serious problems.

-q
     Cause the command to be somewhat quiet; informational messages, such as reports of recursion through subdirectories, are suppressed.

-r
     Make new working files files read-only.  Same effect as if the $CVSREAD environment variable is set (see Environment variables).  The default is to make working files writable, unless watches are on (see Watches).

-s VARIABLE=VALUE
     Set a user variable (see Variables).

-t
     Trace program execution; display messages showing the steps of CVS activity.  Particularly useful with -n to explore the potential impact of an unfamiliar command.

-v
     Display version and copyright information for CVS.

-w
     Make new working files read-write.  Overrides the setting of the $CVSREAD environment variable. Files are created read-write by default, unless $CVSREAD is set or -r is given.

-x
     Encrypt all communication between the client and the server.  Only has an effect on the CVS client.  As of this writing, this is only implemented when using a Kerberos connection (see Kerberos authenticated).

-z GZIP-LEVEL
     Set the compression level.  Only has an effect on the CVS client.

Common command options
======================

This section describes the command_options that are available across several CVS commands.  These options are always given to the right of cvs_command. Not all commands support all of these options; each option is only supported for commands where it makes sense. However, when a command has one of these options you can almost always count on the same behavior of the option as in other commands.  (Other command options, which are listed with the individual commands, may have different behavior from one CVS command to the other).

Warning: the history command is an exception; it supports many options that conflict even with these standard options.

-D DATE_SPEC
     Use the most recent revision no later than DATE_SPEC. DATE_SPEC is a single argument, a date description specifying a date in the past.

     The specification is sticky when you use it to make a private copy of a source file; that is, when you get a working file using -D, CVS records the date you specified, so that further updates in the same directory will use the same date (for more information on sticky tags/dates, see Sticky tags).

     A wide variety of date formats are supported by the underlying RCS facilities, similar to those described in co(1), but not exactly the same.  The DATE_SPEC is interpreted as being in the local timezone, unless a specific timezone is specified. Examples of valid date specifications include:

                              1 month ago
                              2 hours ago
                              400000 seconds ago
                              last year
                              last Monday
                              yesterday
                              a fortnight ago
                              3/31/92 10:00:07 PST
                              January 23, 1987 10:05pm
                              22:00 GMT

     -D is available with the checkout, diff, export, history, rdiff, rtag, and update commands. (The history command uses this option in a slightly different way; see history options).

     Remember to quote the argument to the -D flag so that your shell doesn't interpret spaces as argument separators.  A command using the -D flag can look like this:

          $ cvs diff -D "1 hour ago" cvs.texinfo

-f
     When you specify a particular date or tag to CVS commands, they normally ignore files that do not contain the tag (or did not exist prior to the date) that you specified.  Use the -f option if you want files retrieved even when there is no match for the tag or date.  (The most recent revision of the file will be used).

     -f is available with these commands: checkout, export, rdiff, rtag, and update.

     Warning:  The commit command also has a -f option, but it has a different behavior for that command.  See commit options.

-H
     Help; describe the options available for this command.  This is the only option supported for all CVS commands.

-k KFLAG
     Alter the default RCS processing of keywords. See Keyword substitution, for the meaning of KFLAG.  Your KFLAG specification is sticky when you use it to create a private copy of a source file; that is, when you use this option with the checkout or update commands, CVS associates your selected KFLAG with the file, and continues to use it with future update commands on the same file until you specify otherwise.

     The -k option is available with the add, checkout, diff and update commands.

-l
     Local; run only in current working directory, rather than recursing through subdirectories.

     Warning: this is not the same as the overall cvs -l option, which you can specify to the left of a cvs command!

     Available with the following commands: checkout, commit, diff, export, log, remove, rdiff, rtag, status, tag, and update.

-m MESSAGE
     Use MESSAGE as log information, instead of invoking an editor.

     Available with the following commands: add, commit and import.

-n
     Do not run any checkout/commit/tag program.  (A program can be specified to run on each of these activities, in the modules database (see modules); this option bypasses it).

     Warning: this is not the same as the overall cvs -n option, which you can specify to the left of a cvs command!

     Available with the checkout, commit, export, and rtag commands.

-P
     Prune (remove) directories that are empty after being updated, on checkout, or update.  Normally, an empty directory (one that is void of revision-controlled files) is left alone. Specifying -P will cause these directories to be silently removed from your checked-out sources.  This does not remove the directory from the repository, only from your checked out copy. Note that this option is implied by the -r or -D options of checkout and export.

-p
     Pipe the files retrieved from the repository to standard output, rather than writing them in the current directory.  Available with the checkout and update commands.

-W
     Specify file names that should be filtered.  You can use this option repeatedly.  The spec can be a file name pattern of the same type that you can specify in the .cvswrappers file. Avaliable with the following commands: import, and update.

-r TAG
     Use the revision specified by the TAG argument instead of the default head revision.  As well as arbitrary tags defined with the tag or rtag command, two special tags are always available: HEAD refers to the most recent version available in the repository, and BASE refers to the revision you last checked out into the current working directory.

     The tag specification is sticky when you use this option with checkout or update to make your own copy of a file: CVS remembers the tag and continues to use it on future update commands, until you specify otherwise (for more information on sticky tags/dates, see Sticky tags).  The tag can be either a symbolic or numeric tag. See Tags.

     Specifying the -q global option along with the -r command option is often useful, to suppress the warning messages when the RCS history file does not contain the specified tag.

     Warning: this is not the same as the overall `cvs -r' option, which you can specify to the left of a cvs command!

     -r is available with the checkout, commit, diff, history, export, rdiff, rtag, and update commands.

add---Add a new file/directory to the repository
================================================

  * Synopsis: add [-k kflag] [-m 'message'] files...

  * Requires: repository, working directory.

  * Changes: working directory.

  * Synonym: new

Use the add command to create a new file or directory in the source repository.  The files or directories specified with add must already exist in the current directory (which must have been created with the checkout command).  To add a whole new directory hierarchy to the source repository (for example, files received from a third-party vendor), use the import command instead.  See import.

If the argument to add refers to an immediate sub-directory, the directory is created at the correct place in the source repository, and the necessary CVS administration files are created in your working directory.  If the directory already exists in the source repository, add still creates the administration files in your version of the directory. This allows you to use add to add a particular directory to your private sources even if someone else created that directory after your checkout of the sources.  You can do the following:

     $ mkdir new_directory
     $ cvs add new_directory
     $ cvs update new_directory

An alternate approach using update might be:

     $ cvs update -d new_directory

(To add any available new directories to your working directory, it's probably simpler to use checkout (see checkout) or update -d (see update)).

The added files are not placed in the source repository until you use commit to make the change permanent.  Doing an add on a file that was removed with the remove command will resurrect the file, unless a commit command intervened. See Removing files, for an example.

Unlike most other commands add never recurses down directories.  It cannot yet handle relative paths.  Instead of

     $ cvs add foo/bar.c

you have to do

     $ cd foo
     $ cvs add bar.c

add options
-----------

There are only two options you can give to add:

-k KFLAG
     This option specifies the default way that this file will be checked out.  The KFLAG argument (see Substitution modes) is stored in the RCS file and can be changed with admin -k (see admin options).  See Binary files, for information on using this option for binary files.

-m DESCRIPTION
     Using this option, you can give a description for the file.  This description appears in the history log (if it is enabled, see history file).  It will also be saved in the RCS history file inside the repository when the file is committed.  The log command displays this description.

     The description can be changed using admin -t. See admin.

     If you omit the -m DESCRIPTION flag, an empty string will be used.  You will not be prompted for a description.

add examples
------------

To add the file backend.c to the repository, with a description, the following can be used.

     $ cvs add -m "Optimizer and code generation passes." backend.c
     $ cvs commit -m "Early version. Not yet compilable." backend.c

admin---Administration front end for rcs
========================================

  * Requires: repository, working directory.

  * Changes: repository.

  * Synonym: rcs

This is the CVS interface to assorted administrative RCS facilities, documented in rcs(1).  admin simply passes all its options and arguments to the rcs command; it does no filtering or other processing.  This command does work recursively, however, so extreme care should be used.

If there is a group whose name matches a compiled in value which defaults to cvsadmin, only members of that group can use cvs admin.  To disallow cvs admin for all users, create a group with no users in it.

admin options
-------------

Not all valid rcs options are useful together with CVS.  Some even makes it impossible to use CVS until you undo the effect!

This description of the available options is based on the rcs(1) man page, but modified to suit readers that are more interrested in CVS than RCS.

-AOLDFILE
     Might not work together with CVS.  Append the access list of OLDFILE to the access list of the RCS file.

-aLOGINS
     Might not work together with CVS.  Append the login names appearing in the comma-separated list LOGINS to the access list of the RCS file.

-b[REV]
     When used with bare RCS, this option sets the default branch to REV; in CVS sticky tags (see Sticky tags) are a better way to decide which branch you want to work on.  With CVS, this option can be used to control behavior with respect to the vendor branch.

-cSTRING
     Useful with CVS.  Sets the comment leader to STRING.  The comment leader is printed before every log message line generated by the keyword $Log$ (see Keyword substitution). This is useful for programming languages without multi-line comments.  RCS initially guesses the value of the comment leader from the file name extension when the file is first committed.

-e[LOGINS]
     Might not work together with CVS.  Erase the login names appearing in the comma-separated list LOGINS from the access list of the RCS file.  If LOGINS is omitted, erase the entire access list.

-I
     Run interactively, even if the standard input is not a terminal.

-i
     Useless with CVS.  When using bare RCS, this is used to create and initialize a new RCS file, without depositing a revision.

-kSUBST
     Useful with CVS.  Set the default keyword substitution to SUBST.  See Keyword substitution.  Giving an explicit -k option to cvs update, cvs export, or cvs checkout overrides this default.

-l[REV]
     Lock the revision with number REV.  If a branch is given, lock the latest revision on that branch.  If REV is omitted, lock the latest revision on the default branch.

     This can be used in conjunction with the rcslock.pl script in the contrib directory of the CVS source distribution to provide reserved checkouts (where only one user can be editing a given file at a time).  See the comments in that file for details (and see the README file in that directory for disclaimers about the unsupported nature of contrib).  According to comments in that file, locking must set to strict (which is the default).

-L
     Set locking to strict.  Strict locking means that the owner of an RCS file is not exempt from locking for checkin.  For use with CVS, strict locking must be set; see the discussion under the -l option above.

-mREV:MSG
     Replace the log message of revision REV with MSG.

-NNAME[:[REV]]
     Act like -n, except override any previous assignment of NAME.

-nNAME[:[REV]]
     Associate the symbolic name NAME with the branch or revision REV.  It is normally better to use cvs tag or cvs rtag instead.  Delete the symbolic name if both : and REV are omitted; otherwise, print an error message if NAME is already associated with another number. If REV is symbolic, it is expanded before association.  A REV consisting of a branch number followed by a . stands for the current latest revision in the branch.  A : with an empty REV stands for the current latest revision on the default branch, normally the trunk.  For example, rcs -nNAME: RCS/* associates NAME with the current latest revision of all the named RCS files; this contrasts with rcs -nNAME:$ RCS/* which associates NAME with the revision numbers extracted from keyword strings in the corresponding working files.

-oRANGE
     Potentially useful, but dangerous, with CVS (see below). Deletes (outdates) the revisions given by RANGE.  A range consisting of a single revision number means that revision.  A range consisting of a branch number means the latest revision on that branch. A range of the form REV1:REV2 means revisions REV1 to REV2 on the same branch, :REV means from the beginning of the branch containing REV up to and including REV, and REV: means from revision REV to the end of the branch containing REV.  None of the outdated revisions may have branches or locks.

     Due to the way CVS handles branches REV cannot be specified symbolically if it is a branch. See Magic branch numbers, for an explanation.

     Make sure that no-one has checked out a copy of the revision you outdate.  Strange things will happen if he starts to edit it and tries to check it back in.  For this reason, this option is not a good way to take back a bogus commit; commit a new revision undoing the bogus change instead (see Merging two revisions).

-q
     Run quietly; do not print diagnostics.

-sSTATE[:REV]
     Useful with CVS.  Set the state attribute of the revision REV to STATE.  If REV is a branch number, assume the latest revision on that branch.  If REV is omitted, assume the latest revision on the default branch.  Any identifier is acceptable for STATE.  A useful set of states is Exp (for experimental), Stab (for stable), and Rel (for released).  By default, the state of a new revision is set to Exp when it is created.  The state is visible in the output from CVS LOG (see log), and in the $Log$ and $State$ keywords (see Keyword substitution).  Note that CVS uses the dead state for its own purposes; to take a file to or from the dead state use commands like cvs remove and cvs add, not cvs admin -s.

-t[FILE]
     Useful with CVS.  Write descriptive text from the contents of the named FILE into the RCS file, deleting the existing text.  The FILE pathname may not begin with -.  If FILE is omitted, obtain the text from standard input, terminated by end-of-file or by a line containing . by itself. Prompt for the text if interaction is possible; see -I.  The descriptive text can be seen in the output from cvs log (see log).

-t-STRING
     Similar to -tFILE. Write descriptive text from the STRING into the RCS file, deleting the existing text.

-U
     Set locking to non-strict.  Non-strict locking means that the owner of a file need not lock a revision for checkin.  For use with CVS, strict locking must be set; see the discussion under the -l option above.

-u[REV]
     See the option -l above, for a discussion of using this option with CVS.  Unlock the revision with number REV.  If a branch is given, unlock the latest revision on that branch.  If REV is omitted, remove the latest lock held by the caller. Normally, only the locker of a revision may unlock it. Somebody else unlocking a revision breaks the lock. This causes a mail message to be sent to the original locker.  The message contains a commentary solicited from the breaker.  The commentary is terminated by end-of-file or by a line containing . by itself.

-VN
     Emulate RCS version N. Use -VN to make an RCS file acceptable to RCS version N by discarding information that would confuse version N.

-xSUFFIXES
     Useless with CVS. Use SUFFIXES to characterize RCS files.

admin examples
--------------

Outdating is dangerous
......................

First, an example of how not to use the admin command.  It is included to stress the fact that this command can be quite dangerous unless you know exactly what you are doing.

The -o option can be used to outdate old revisions from the history file.  If you are short on disc this option might help you.  But think twice before using it---there is no way short of restoring the latest backup to undo this command!

The next line is an example of a command that you would not like to execute.

     $ cvs admin -o:R_1_02 .

The above command will delete all revisions up to, and including, the revision that corresponds to the tag R_1_02.  But beware!  If there are files that have not changed between R_1_02 and R_1_03 the file will have the same numerical revision number assigned to the tags R_1_02 and R_1_03.  So not only will it be impossible to retrieve R_1_02; R_1_03 will also have to be restored from the tapes!

Comment leaders
...............

If you use the $Log$ keyword and you do not agree with the guess for comment leader that CVS has done, you can enforce your will with cvs admin -c.  This might be suitable for nroff source:

     $ cvs admin -c'.\" ' *.man
     $ rm *.man
     $ cvs update

The two last steps are to make sure that you get the versions with correct comment leaders in your working files.

checkout---Check out sources for editing
========================================

  * Synopsis: checkout [options] modules...

  * Requires: repository.

  * Changes: working directory.

  * Synonyms: co, get

Make a working directory containing copies of the source files specified by MODULES.  You must execute checkout before using most of the other CVS commands, since most of them operate on your working directory.

The MODULES part of the command are either symbolic names for some collection of source directories and files, or paths to directories or files in the repository.  The symbolic names are defined in the modules file. See modules.

Depending on the modules you specify, checkout may recursively create directories and populate them with the appropriate source files.  You can then edit these source files at any time (regardless of whether other software developers are editing their own copies of the sources); update them to include new changes applied by others to the source repository; or commit your work as a permanent change to the source repository.

Note that checkout is used to create directories.  The top-level directory created is always added to the directory where checkout is invoked, and usually has the same name as the specified module.  In the case of a module alias, the created sub-directory may have a different name, but you can be sure that it will be a sub-directory, and that checkout will show the relative path leading to each file as it is extracted into your private work area (unless you specify the -Q global option).

The files created by checkout are created read-write, unless the -r option to CVS (see Global options) is specified, the CVSREAD environment variable is specified (see Environment variables), or a watch is in effect for that file (see Watches).

Running checkout on a directory that was already built by a prior checkout is also permitted, and has the same effect as specifying the -d option to the update command, that is, any new directories that have been created in the repository will appear in your work area.  See update.

checkout options
----------------

These standard options are supported by checkout (see Common options, for a complete description of them):

-D DATE
     Use the most recent revision no later than DATE. This option is sticky, and implies -P.  See Sticky tags, for more information on sticky tags/dates.

-f
     Only useful with the -D DATE or -r TAG flags.  If no matching revision is found, retrieve the most recent revision (instead of ignoring the file).

-k KFLAG
     Process RCS keywords according to KFLAG.  See co(1).  This option is sticky; future updates of this file in this working directory will use the same KFLAG.  The status command can be viewed to see the sticky options.  See status.

-l
     Local; run only in current working directory.

-n
     Do not run any checkout program (as specified with the -o option in the modules file; see modules).

-P
     Prune empty directories.

-p
     Pipe files to the standard output.

-r TAG
     Use revision TAG.  This option is sticky, and implies -P. See Sticky tags, for more information on sticky tags/dates.

In addition to those, you can use these special command options with checkout:

-A
     Reset any sticky tags, dates, or -k options. See Sticky tags, for more information on sticky tags/dates.

-c
     Copy the module file, sorted, to the standard output, instead of creating or modifying any files or directories in your working directory.

-d DIR
     Create a directory called DIR for the working files, instead of using the module name.  Unless you also use -N, the paths created under DIR will be as short as possible.

-j TAG
     With two -j options, merge changes from the revision specified with the first -j option to the revision specified with the second j option, into the working directory.

     With one -j option, merge changes from the ancestor revision to the revision specified with the -j option, into the working directory.  The ancestor revision is the common ancestor of the revision which the working directory is based on, and the revision specified in the -j option.

     In addition, each -j option can contain an optional date specification which, when used with branches, can limit the chosen revision to one within a specific date.  An optional date is specified by adding a colon (:) to the tag: -jSYMBOLIC_TAG:DATE_SPECIFIER.

     See Merging.

-N
     Only useful together with -d DIR.  With this option, CVS will not shorten module paths in your working directory.  (Normally, CVS shortens paths as much as possible when you specify an explicit target directory).

-s
     Like -c, but include the status of all modules, and sort it by the status string.  See modules, for info about the -s option that is used inside the modules file to set the module status.

checkout examples
-----------------

Get a copy of the module tc:

     $ cvs checkout tc

Get a copy of the module tc as it looked one day ago:

     $ cvs checkout -D yesterday tc

commit---Check files into the repository
========================================

  * Version 1.3 Synopsis: commit [-lnR] [-m 'log_message' | -f file] [-r revision] [files...]

  * Version 1.3.1 Synopsis: commit [-lnRf] [-m 'log_message' | -F file] [-r revision] [files...]

  * Requires: working directory, repository.

  * Changes: repository.

  * Synonym: ci

Warning: The -f FILE option will probably be renamed to -F FILE, and -f will be given a new behavior in future releases of CVS.

Use commit when you want to incorporate changes from your working source files into the source repository.

If you don't specify particular files to commit, all of the files in your working current directory are examined.  commit is careful to change in the repository only those files that you have really changed.  By default (or if you explicitly specify the -R option), files in subdirectories are also examined and committed if they have changed; you can use the -l option to limit commit to the current directory only.

commit verifies that the selected files are up to date with the current revisions in the source repository; it will notify you, and exit without committing, if any of the specified files must be made current first with update (see update). commit does not call the update command for you, but rather leaves that for you to do when the time is right.

When all is well, an editor is invoked to allow you to enter a log message that will be written to one or more logging programs (see modules, and see loginfo) and placed in the RCS history file inside the repository.  This log message can be retrieved with the log command; see log.  You can specify the log message on the command line with the -m MESSAGE option, and thus avoid the editor invocation, or use the -f FILE option to specify that the argument file contains the log message.

commit options
--------------

These standard options are supported by commit (see Common options, for a complete description of them):

-l
     Local; run only in current working directory.

-n
     Do not run any module program.

-R
     Commit directories recursively.  This is on by default.

-r REVISION
     Commit to REVISION.  REVISION must be either a branch, or a revision on the main trunk that is higher than any existing revision number.  You cannot commit to a specific revision on a branch.

commit also supports these options:

-F FILE
     This option is present in CVS releases 1.3-s3 and later.  Read the log message from FILE, instead of invoking an editor.

-f
     This option is present in CVS 1.3-s3 and later releases of CVS.  Note that this is not the standard behavior of the -f option as defined in see Common options.

     Force CVS to commit a new revision even if you haven't made any changes to the file.  If the current revision of FILE is 1.7, then the following two commands are equivalent:

          $ cvs commit -f FILE
          $ cvs commit -r 1.8 FILE

-f FILE
     This option is present in CVS releases 1.3, 1.3-s1 and 1.3-s2.  Note that this is not the standard behavior of the -f option as defined in see Common options.

     Read the log message from FILE, instead of invoking an editor.

-m MESSAGE
     Use MESSAGE as the log message, instead of invoking an editor.

commit examples
---------------

New major release number
........................

When you make a major release of your product, you might want the revision numbers to track your major release number.  You should normally not care about the revision numbers, but this is a thing that many people want to do, and it can be done without doing any harm.

To bring all your files up to the RCS revision 3.0 (including those that haven't changed), you might do:

     $ cvs commit -r 3.0

Note that it is generally a bad idea to try to make the RCS revision number equal to the current release number of your product.  You should think of the revision number as an internal number that the CVS package maintains, and that you generally never need to care much about.  Using the tag and rtag commands you can give symbolic names to the releases instead.  See tag, and see rtag.

Note that the number you specify with -r must be larger than any existing revision number.  That is, if revision 3.0 exists, you cannot cvs commit -r 1.3.

Committing to a branch
......................

You can commit to a branch revision (one that has an even number of dots) with the -r option.  To create a branch revision, use the -b option of the rtag or tag commands (see tag or see rtag).  Then, either checkout or update can be used to base your sources on the newly created branch.  From that point on, all commit changes made within these working sources will be automatically added to a branch revision, thereby not disturbing main-line development in any way.  For example, if you had to create a patch to the 1.2 version of the product, even though the 2.0 version is already under development, you might do:

     $ cvs rtag -b -r FCS1_2 FCS1_2_Patch product_module
     $ cvs checkout -r FCS1_2_Patch product_module
     $ cd product_module
     [[ hack away ]]
     $ cvs commit

This works automatically since the -r option is sticky.

Creating the branch after editing
.................................

Say you have been working on some extremely experimental software, based on whatever revision you happened to checkout last week.  If others in your group would like to work on this software with you, but without disturbing main-line development, you could commit your change to a new branch.  Others can then checkout your experimental stuff and utilize the full benefit of CVS conflict resolution.  The scenario might look like:

     [[ hacked sources are present ]]
     $ cvs tag -b EXPR1
     $ cvs update -r EXPR1
     $ cvs commit

The update command will make the -r EXPR1 option sticky on all files.  Note that your changes to the files will never be removed by the update command.  The commit will automatically commit to the correct branch, because the -r is sticky.  You could also do like this:

     [[ hacked sources are present ]]
     $ cvs tag -b EXPR1
     $ cvs commit -r EXPR1

but then, only those files that were changed by you will have the -r EXPR1 sticky flag.  If you hack away, and commit without specifying the -r EXPR1 flag, some files may accidentally end up on the main trunk.

To work with you on the experimental change, others would simply do

     $ cvs checkout -r EXPR1 whatever_module

diff---Run diffs between revisions
==================================

  * Synopsis: diff [-l] [rcsdiff_options] [[-r rev1 | -D date1] [-r rev2 |  -D date2]] [files...]

  * Requires: working directory, repository.

  * Changes: nothing.

The diff command is used to compare different revisions of files.  The default action is to compare your working files with the revisions they were based on, and report any differences that are found.

If any file names are given, only those files are compared.  If any directories are given, all files under them will be compared.

The exit status will be 0 if no differences were found, 1 if some differences were found, and 2 if any error occurred.

diff options
------------

These standard options are supported by diff (see Common options, for a complete description of them):

-D DATE
     Use the most recent revision no later than DATE. See -r for how this affects the comparison.

     CVS can be configured to pass the -D option through to rcsdiff (which in turn passes it on to diff.  GNU diff uses -D as a way to put cpp-style #define statements around the output differences.  There is no way short of testing to figure out how CVS was configured.  In the default configuration CVS will use the -D DATE option.

-k KFLAG
     Process RCS keywords according to KFLAG.  See co(1).

-l
     Local; run only in current working directory.

-R
     Examine directories recursively.  This option is on by default.

-r TAG
     Compare with revision TAG.  Zero, one or two -r options can be present.  With no -r option, the working file will be compared with the revision it was based on.  With one -r, that revision will be compared to your current working file. With two -r options those two revisions will be compared (and your working file will not affect the outcome in any way).

     One or both -r options can be replaced by a -D DATE option, described above.

Any other options that are found are passed through to rcsdiff, which in turn passes them to diff.  The exact meaning of the options depends on which diff you are using.  The long options introduced in GNU diff 2.0 are not yet supported in CVS.  See the documentation for your diff to see which options are supported.

diff examples
-------------

The following line produces a Unidiff (-u flag) between revision 1.14 and 1.19 of backend.c.  Due to the -kk flag no keywords are substituted, so differences that only depend on keyword substitution are ignored.

     $ cvs diff -kk -u -r 1.14 -r 1.19 backend.c

Suppose the experimental branch EXPR1 was based on a set of files tagged RELEASE_1_0.  To see what has happened on that branch, the following can be used:

     $ cvs diff -r RELEASE_1_0 -r EXPR1

A command like this can be used to produce a context diff between two releases:

     $ cvs diff -c -r RELEASE_1_0 -r RELEASE_1_1 > diffs

If you are maintaining ChangeLogs, a command like the following just before you commit your changes may help you write the ChangeLog entry.  All local modifications that have not yet been committed will be printed.

     $ cvs diff -u | less

export---Export sources from CVS, similar to checkout
=====================================================

  * Synopsis: export [-flNn] [-r rev|-D date] [-k subst] [-d dir] module...

  * Requires: repository.

  * Changes: current directory.

This command is a variant of checkout; use it when you want a copy of the source for module without the CVS administrative directories.  For example, you might use export to prepare source for shipment off-site.  This command requires that you specify a date or tag (with -D or -r), so that you can count on reproducing the source you ship to others.

One often would like to use -kv with cvs export.  This causes any RCS keywords to be expanded such that an import done at some other site will not lose the keyword revision information.  But be aware that doesn't handle an export containing binary files correctly.  Also be aware that after having used -kv, one can no longer use the ident command (which is part of the RCS suite---see ident(1)) which looks for RCS keyword strings.  If you want to be able to use ident you must not use -kv.

export options
--------------

These standard options are supported by export (see Common options, for a complete description of them):

-D DATE
     Use the most recent revision no later than DATE.

-f
     If no matching revision is found, retrieve the most recent revision (instead of ignoring the file).

-l
     Local; run only in current working directory.

-n
     Do not run any checkout program.

-R
     Export directories recursively.  This is on by default.

-r TAG
     Use revision TAG.

In addition, these options (that are common to checkout and export) are also supported:

-d DIR
     Create a directory called DIR for the working files, instead of using the module name.  Unless you also use -N, the paths created under DIR will be as short as possible.

-k SUBST
     Set keyword expansion mode (see Substitution modes).

-N
     Only useful together with -d DIR.  With this option, CVS will not shorten module paths in your working directory.  (Normally, CVS shortens paths as much as possible when you specify an explicit target directory.)

history---Show status of files and users
========================================

  * Synopsis:     history [-report] [-flags] [-options args] [files...]

  * Requires: the file $CVSROOT/CVSROOT/history

  * Changes: nothing.

CVS can keep a history file that tracks each use of the checkout, commit, rtag, update, and release commands.  You can use history to display this information in various formats.

Logging must be enabled by creating the file $CVSROOT/CVSROOT/history.

Warning: history uses -f, -l, -n, and -p in ways that conflict with the normal use inside CVS (see Common options).

history options
---------------

Several options (shown above as -report)  control  what kind of report is generated:

-c
     Report on each time commit was used (i.e., each time the repository was modified).

-e
     Everything (all record types); equivalent to specifying -xMACFROGWUT.

-m MODULE
     Report on a particular module.  (You can meaningfully use -m more than once on the command line.)

-o
     Report on checked-out modules.

-T
     Report on all tags.

-x TYPE
     Extract a particular set of record types TYPE from the CVS history.  The types are indicated by single letters, which you may specify in combination.

     Certain commands have a single record type:

     F
          release

     O
          checkout

     T
          rtag

     One of four record types may result from an update:

     C
          A merge was necessary but collisions were detected (requiring manual merging).

     G
          A merge was necessary and it succeeded.

     U
          A working file was copied from the repository.

     W
          The working copy of a file was deleted during update (because it was gone from the repository).

     One of three record types results from commit:

     A
          A file was added for the first time.

     M
          A file was modified.

     R
          A file was removed.

The options shown as -flags constrain or expand the report without requiring option arguments:

-a
     Show data for all users (the default is to show data only for the user executing history).

-l
     Show last modification only.

-w
     Show only the records for modifications done from the same working directory where history is executing.

The options shown as -options ARGS constrain the report based on an argument:

-b STR
     Show data back to a record containing  the  string STR  in  either the module name, the file name, or the repository path.

-D DATE
     Show data since DATE.  This is slightly different from the normal use of -D DATE, which selects the newest revision older than DATE.

-p REPOSITORY
     Show data for a particular source repository  (you can specify several -p options on the same command line).

-r REV
     Show records referring to revisions since the revision or tag named REV appears in individual RCS files.  Each RCS file is searched for the revision or tag.

-t TAG
     Show records since tag TAG was last added to the the history file.  This differs from the -r flag above in that it reads only the history file, not the RCS files, and is much faster.

-u NAME
     Show records for user NAME.

import---Import sources into CVS, using vendor branches
=======================================================

  * Synopsis: import [-options] repository vendortag releasetag...

  * Requires: Repository, source distribution directory.

  * Changes: repository.

Use import to incorporate an entire source distribution from an outside source (e.g., a source vendor) into your source repository directory.  You can use this command both for initial creation of a repository, and for wholesale updates to the module from the outside source.  See Tracking sources, for a discussion on this subject.

The REPOSITORY argument gives a directory name (or a path to a directory) under the CVS root directory for repositories; if the directory did not exist, import creates it.

When you use import for updates to source that has been modified in your source repository (since a prior import), it will notify you of any files that conflict in the two branches of development; use checkout -j to reconcile the differences, as import instructs you to do.

If CVS decides a file should be ignored (see cvsignore), it does not import it and prints I  followed by the filename

If the file $CVSROOT/CVSROOT/cvswrappers exists, any file whose names match the specifications in that file will be treated as packages and the appropriate filtering will be performed on the file/directory before being imported, see Wrappers.

The outside source is saved in a first-level RCS branch, by default 1.1.1.  Updates are leaves of this branch; for example, files from the first imported collection of source will be revision 1.1.1.1, then files from the first imported update will be revision 1.1.1.2, and so on.

At least three arguments are required. REPOSITORY is needed to identify the collection of source.  VENDORTAG is a tag for the entire branch (e.g., for 1.1.1).  You must also specify at least one RELEASETAG to identify the files at the leaves created each time you execute import.

import options
--------------

This standard option is supported by import (see Common options, for a complete description):

-m MESSAGE
     Use MESSAGE as log information, instead of invoking an editor.

There are three additional special options.

-b BRANCH
     Specify a first-level branch other than 1.1.1.  Unless the -b BRANCH flag is given, revisions will always be made to the branch 1.1.1---even if a VENDORTAG that matches another branch is given! What happens in that case, is that the tag will be reset to 1.1.1.  Warning: This behavior might change in the future.

-k SUBST
     Indicate the RCS keyword expansion mode desired.  This setting will apply to all files created during the import, but not to any files that previously existed in the repository.  See Substitution modes, for a list of valid -k settings.

-I NAME
     Specify file names that should be ignored during import.  You can use this option repeatedly.  To avoid ignoring any files at all (even those ignored by default), specify `-I !'.

     NAME can be a file name pattern of the same type that you can specify in the .cvsignore file. See cvsignore.

-W SPEC
     Specify file names that should be filtered during import.  You can use this option repeatedly.

     SPEC can be a file name pattern of the same type that you can specify in the .cvswrappers file. See Wrappers.

import examples
---------------

See Tracking sources, and see From files.

log---Print out log information for files
=========================================

  * Synopsis: log [options] [files...]

  * Requires: repository, working directory.

  * Changes: nothing.

Display log information for files.  log used to call the RCS utility rlog.  Although this is no longer true in the current sources, this history determines the format of the output and the options, which are not quite in the style of the other CVS commands.

The output includes the location of the RCS file, the head revision (the latest revision on the trunk), all symbolic names (tags) and some other things.  For each revision, the revision number, the author, the number of lines added/deleted and the log message are printed.  All times are displayed in Coordinated Universal Time (UTC).  (Other parts of CVS print times in the local timezone).

log options
-----------

By default, log prints all information that is available.  All other options restrict the output.

-b
     Print information about the revisions on the default branch, normally the highest branch on the trunk.

-d DATES
     Print information about revisions with a checkin date/time in the range given by the semicolon-separated list of dates.  The following table explains the available range formats:

     D1<D2
     D2>D1
          Select the revisions that were deposited between D1 and D2.

     <D
     D>
          Select all revisions dated D or earlier.

     D<
     >D
          Select all revisions dated D or later.

     D
          Select the single, latest revision dated D or earlier.

     The > or < characters may be followed by = to indicate an inclusive range rather than an exclusive one.

     Note that the separator is a semicolon (;).

-h
     Print only the RCS pathname, working pathname, head, default branch, access list, locks, symbolic names, and suffix.

-l
     Local; run only in current working directory.  (Default is to run recursively).

-N
     Do not print the list of tags for this file.  This option can be very useful when your site uses a lot of tags, so rather than "more"'ing over 3 pages of tag information, the log information is presented without tags at all.

-R
     Print only the name of the RCS history file.

-rREVISIONS
     Print information about revisions given in the comma-separated list REVISIONS of revisions and ranges.  The following table explains the available range formats:

     REV1:REV2
          Revisions REV1 to REV2 (which must be on the same branch).

     :REV
          Revisions from the beginning of the branch up to and including REV.

     REV:
          Revisions starting with REV to the end of the branch containing REV.

     BRANCH
          An argument that is a branch means all revisions on that branch.

     BRANCH1:BRANCH2
          A range of branches means all revisions on the branches in that range.

     BRANCH.
          The latest revision in BRANCH.

     A bare -r with no revisions means the latest revision on the default branch, normally the trunk. There can be no space between the -r option and its argument.

-s STATES
     Print information about revisions whose state attributes match one of the states given in the comma-separated list STATES.

-t
     Print the same as -h, plus the descriptive text.

-wLOGINS
     Print information about revisions checked in by users with login names appearing in the comma-separated list LOGINS.  If LOGINS is omitted, the user's login is assumed.  There can be no space between the -w option and its argument.

log prints the intersection of the revisions selected with the options -d, -s, and -w, intersected with the union of the revisions selected by -b and -r.

log examples
------------

Contributed examples are gratefully accepted.

rdiff---'patch' format diffs between releases
=============================================

  * rdiff [-flags] [-V vn] [-r t|-D d [-r t2|-D d2]] modules...

  * Requires: repository.

  * Changes: nothing.

  * Synonym: patch

Builds a Larry Wall format patch(1) file between two releases, that can be fed directly into the patch program to bring an old release up-to-date with the new release.  (This is one of the few CVS commands that operates directly from the repository, and doesn't require a prior checkout.) The diff output is sent to the standard output device.

You can specify (using the standard -r and -D options) any combination of one or two revisions or dates.  If only one revision or date is specified, the patch file reflects differences between that revision or date and the current head revisions in the RCS file.

Note that if the software release affected is contained in more than one directory, then it may be necessary to specify the -p option to the patch command when patching the old sources, so that patch is able to find the files that are located in other directories.

rdiff options
-------------

These standard options are supported by rdiff (see Common options, for a complete description of them):

-D DATE
     Use the most recent revision no later than DATE.

-f
     If no matching revision is found, retrieve the most recent revision (instead of ignoring the file).

-l
     Local; don't descend subdirectories.

-r TAG
     Use revision TAG.

In addition to the above, these options are available:

-c
     Use the context diff format.  This is the default format.

-s
     Create a summary change report instead of a patch.  The summary includes information about files that were changed or added between the releases.  It is sent to the standard output device.  This is useful for finding out, for example, which files have changed between two dates or revisions.

-t
     A diff of the top two revisions is sent to the standard output device.  This is most useful for seeing what the last change to a file was.

-u
     Use the unidiff format for the context diffs. This option is not available if your diff does not support the unidiff format.  Remember that old versions of the patch program can't handle the unidiff format, so if you plan to post this patch to the net you should probably not use -u.

-V VN
     Expand RCS keywords according to the rules current in RCS version VN (the expansion format changed with RCS version 5).

rdiff examples
--------------

Suppose you receive mail from foo@bar.com asking for an update from release 1.2 to 1.4 of the tc compiler.  You have no such patches on hand, but with CVS that can easily be fixed with a command such as this:

     $ cvs rdiff -c -r FOO1_2 -r FOO1_4 tc | \
     $$ Mail -s 'The patches you asked for' foo@bar.com

Suppose you have made release 1.3, and forked a branch called R_1_3fix for bugfixes.  R_1_3_1 corresponds to release 1.3.1, which was made some time ago.  Now, you want to see how much development has been done on the branch.  This command can be used:

     $ cvs patch -s -r R_1_3_1 -r R_1_3fix module-name
     cvs rdiff: Diffing module-name
     File ChangeLog,v changed from revision 1.52.2.5 to 1.52.2.6
     File foo.c,v changed from revision 1.52.2.3 to 1.52.2.4
     File bar.h,v changed from revision 1.29.2.1 to 1.2

release---Indicate that a Module is no longer in use
====================================================

  * release [-d] directories...

  * Requires: Working directory.

  * Changes: Working directory, history log.

This command is meant to safely cancel the effect of cvs checkout.  Since CVS doesn't lock files, it isn't strictly necessary to use this command.  You can always simply delete your working directory, if you like; but you risk losing changes you may have forgotten, and you leave no trace in the CVS history file (see history file) that you've abandoned your checkout.

Use cvs release to avoid these problems.  This command checks that no uncommitted changes are present; that you are executing it from immediately above a CVS working directory; and that the repository recorded for your files is the same as the repository defined in the module database.

If all these conditions are true, cvs release leaves a record of its execution (attesting to your intentionally abandoning your checkout) in the CVS history log.

release options
---------------

The release command supports one command option:

-d
     Delete your working copy of the file if the release succeeds.  If this flag is not given your files will remain in your working directory.

     Warning:  The release command uses rm -r module to delete your file.  This has the very serious side-effect that any directory that you have created inside your checked-out sources, and not added to the repository (using the add command; see add) will be silently deleted---even if it is non-empty!

release output
--------------

Before release releases your sources it will print a one-line message for any file that is not up-to-date.

Warning:  Any new directories that you have created, but not added to the CVS directory hierarchy with the add command (see add) will be silently ignored (and deleted, if -d is specified), even if they contain files.

U FILE
     There exists a newer revision of this file in the repository, and you have not modified your local copy of the file.

A FILE
     The file has been added to your private copy of the sources, but has not yet been committed to the repository.  If you delete your copy of the sources this file will be lost.

R FILE
     The file has been removed from your private copy of the sources, but has not yet been removed from the repository, since you have not yet committed the removal.  See commit.

M FILE
     The file is modified in your working directory.  There might also be a newer revision inside the repository.

? FILE
     FILE is in your working directory, but does not correspond to anything in the source repository, and is not in the list of files for CVS to ignore (see the description of the -I option, and see cvsignore).  If you remove your working sources, this file will be lost.

     Note that no warning message like this is printed for spurious directories that CVS encounters.  The directory, and all its contents, are silently ignored.

release examples
----------------

Release the module, and delete your local working copy of the files.

     $ cd ..         # You must stand immediately above the
                     # sources when you issue cvs release.
     $ cvs release -d tc
     You have [0] altered files in this repository.
     Are you sure you want to release (and delete) module `tc': y
     $

rtag---Add a symbolic tag to a module
=====================================

  * rtag [-falnR] [-b] [-d] [-r tag | -Ddate] symbolic_tag modules...

  * Requires: repository.

  * Changes: repository.

  * Synonym: rfreeze

You can use this command to assign symbolic tags to particular, explicitly specified source revisions in the repository.  rtag works directly on the repository contents (and requires no prior checkout). Use tag instead (see tag), to base the selection of revisions on the contents of your working directory.

If you attempt to use a tag name that already exists, CVS will complain and not overwrite that tag.  Use the -F option to force the new tag value.

rtag options
------------

These standard options are supported by rtag (see Common options, for a complete description of them):

-D DATE
     Tag the most recent revision no later than DATE.

-f
     Only useful with the -D DATE or -r TAG flags.  If no matching revision is found, use the most recent revision (instead of ignoring the file).

-F
     Overwrite an existing tag of the same name on a different revision.  This option is new in CVS 1.4.  The old behavior is matched by cvs tag -F.

-l
     Local; run only in current working directory.

-n
     Do not run any tag program that was specified with the -t flag inside the modules file. (see modules).

-R
     Commit directories recursively.  This is on by default.

-r TAG
     Only tag those files that contain TAG.  This can be used to rename a tag: tag only the files identified by the old tag, then delete the old tag, leaving the new tag on exactly the same files as the old tag.

In addition to the above common options, these options are available:

-a
     Use the -a option to have rtag look in the Attic (see Removing files) for removed files that contain the specified tag.  The tag is removed from these files, which makes it convenient to re-use a symbolic tag as development continues (and files get removed from the up-coming distribution).

-b
     Make the tag a branch tag.  See Branches.

-d
     Delete the tag instead of creating it.

     In general, tags (often the symbolic names of software distributions) should not be removed, but the -d option is available as a means to remove completely obsolete symbolic names if necessary (as might be the case for an Alpha release, or if you mistagged a module).

status---Display status information on checked out files
========================================================

  * status [-lR] [-v] [files...]

  * Requires: working directory, repository.

  * Changes: nothing.

Display a brief report on the current status of files with respect to the source repository, including any sticky tags, dates, or -k options.

You can also use this command to determine the potential impact of a cvs update on your working source directory---but remember that things might change in the repository before you run update.

status options
--------------

These standard options are supported by status (see Common options, for a complete description of them):

-l
     Local; run only in current working directory.

-R
     Commit directories recursively.  This is on by default.

There is one additional option:

-v
     Verbose.  In addition to the information normally displayed, print all symbolic tags, together with the numerical value of the revision or branch they refer to.

tag---Add a symbolic tag to checked out versions of files
=========================================================

  * tag [-lR] [-b] [-c] [-d] symbolic_tag [files...]

  * Requires: working directory, repository.

  * Changes: repository.

  * Synonym: freeze

Use this command to assign symbolic tags to the nearest repository versions to your working sources.  The tags are applied immediately to the repository, as with rtag, but the versions are supplied implicitly by the CVS records of your working files' history rather than applied explicitly.

One use for tags is to record a snapshot of the current sources when the software freeze date of a project arrives.  As bugs are fixed after the freeze date, only those changed sources that are to be part of the release need be re-tagged.

The symbolic tags are meant to permanently record which revisions of which files were used in creating a software distribution.  The checkout and update commands allow you to extract an exact copy of a tagged release at any time in the future, regardless of whether files have been changed, added, or removed since the release was tagged.

This command can also be used to delete a symbolic tag, or to create a branch.  See the options section below.

If you attempt to use a tag name that already exists, CVS will complain and not overwrite that tag.  Use the -F option to force the new tag value.

tag options
-----------

These standard options are supported by tag (see Common options, for a complete description of them):

-F
     Overwrite an existing tag of the same name on a different revision.  This option is new in CVS 1.4.  The old behavior is matched by cvs tag -F.

-l
     Local; run only in current working directory.

-R
     Commit directories recursively.  This is on by default.

Two special options are available:

-b
     The -b option makes the tag a branch tag (see Branches), allowing concurrent, isolated development.  This is most useful for creating a patch to a previously released software distribution.

-c
     The -c option checks that all files which are to be tagged are unmodified.  This can be used to make sure that you can reconstruct the current file contents.

-d
     Delete a tag.

     If you use cvs tag -d symbolic_tag, the symbolic tag you specify is deleted instead of being added. Warning: Be very certain of your ground before you delete a tag; doing this permanently discards some historical information, which may later turn out to be valuable.

update---Bring work tree in sync with repository
================================================

  * update [-AdflPpR] [-d] [-r tag|-D date] files...

  * Requires: repository, working directory.

  * Changes: working directory.

After you've run checkout to create your private copy of source from the common repository, other developers will continue changing the central source.  From time to time, when it is convenient in your development process, you can use the update command from within your working directory to reconcile your work with any revisions applied to the source repository since your last checkout or update.

update options
--------------

These standard options are available with update (see Common options, for a complete description of them):

-D date
     Use the most recent revision no later than DATE. This option is sticky, and implies -P. See Sticky tags, for more information on sticky tags/dates.

-f
     Only useful with the -D DATE or -r TAG flags.  If no matching revision is found, retrieve the most recent revision (instead of ignoring the file).

-k KFLAG
     Process RCS keywords according to KFLAG.  See co(1).  This option is sticky; future updates of this file in this working directory will use the same KFLAG.  The status command can be viewed to see the sticky options.  See status.

-l
     Local; run only in current working directory.  See Recursive behavior.

-P
     Prune empty directories.

-p
     Pipe files to the standard output.

-R
     Operate recursively.  This is on by default. See Recursive behavior.

-r tag
     Retrieve revision TAG.  This option is sticky, and implies -P. See Sticky tags, for more information on sticky tags/dates.

These special options are also available with update.

-A
     Reset any sticky tags, dates, or -k options. See Sticky tags, for more information on sticky tags/dates.

-d
     Create any directories that exist in the repository if they're missing from the working directory.  Normally, update acts only on directories and files that were already enrolled in your working directory.

     This is useful for updating directories that were created in the repository since the initial checkout; but it has an unfortunate side effect.  If you deliberately avoided certain directories in the repository when you created your working directory (either through use of a module name or by listing explicitly the files and directories you wanted on the command line), then updating with -d will create those directories, which may not be what you want.

-I NAME
     Ignore files whose names match NAME (in your working directory) during the update.  You can specify -I more than once on the command line to specify several files to ignore.  Use -I ! to avoid ignoring any files at all.  See cvsignore, for other ways to make CVS ignore some files.

-WSPEC
     Specify file names that should be filtered during update.  You can use this option repeatedly.

     SPEC can be a file name pattern of the same type that you can specify in the .cvswrappers file. See Wrappers.

-jREVISION
     With two -j options, merge changes from the revision specified with the first -j option to the revision specified with the second j option, into the working directory.

     With one -j option, merge changes from the ancestor revision to the revision specified with the -j option, into the working directory.  The ancestor revision is the common ancestor of the revision which the working directory is based on, and the revision specified in the -j option.

     In addition, each -j option can contain an optional date specification which, when used with branches, can limit the chosen revision to one within a specific date.  An optional date is specified by adding a colon (:) to the tag: -jSYMBOLIC_TAG:DATE_SPECIFIER.

     See Merging.

update output
-------------

update keeps you informed of its progress by printing a line for each file, preceded by one character indicating the status of the file:

U FILE
     The file was brought up to date with respect to the repository.  This is done for any file that exists in the repository but not in your source, and for files that you haven't changed but are not the most recent versions available in the repository.

A FILE
     The file has been added to your private copy of the sources, and will be added to the source repository when you run commit on the file.  This is a reminder to you that the file needs to be committed.

R FILE
     The file has been removed from your private copy of the sources, and will be removed from the source repository when you run commit on the file.  This is a reminder to you that the file needs to be committed.

M FILE
     The file is modified in  your  working  directory.

     M can indicate one of two states for a file you're working on: either there were no modifications to the same file in the repository, so that your file remains as you last saw it; or there were modifications in the repository as well as in your copy, but they were merged successfully, without conflict, in your working directory.

     CVS will print some messages if it merges your work, and a backup copy of your working file (as it looked before you ran update) will be made.  The exact name of that file is printed while update runs.

C FILE
     A conflict was detected while trying to merge your changes to FILE with changes from the source repository.  FILE (the copy in your working directory) is now the output of the rcsmerge(1) command on the two revisions; an unmodified copy of your file is also in your working directory, with the name .#FILE.REVISION where REVISION is the RCS revision that your modified file started from.  (Note that some systems automatically purge files that begin with .# if they have not been accessed for a few days.  If you intend to keep a copy of your original file, it is a very good idea to rename it.)

? FILE
     FILE is in your working directory, but does not correspond to anything in the source repository, and is not in the list of files for CVS to ignore (see the description of the -I option, and see cvsignore).

     Note that no warning message like this is printed for spurious directories that CVS encounters.  The directory, and all its contents, are silently ignored.

update examples
---------------

The following line will display all files which are not up-to-date without actually change anything in your working directory.  It can be used to check what has been going on with the project.

     $ cvs -n -q update

Reference manual for the Administrative files
*********************************************

Inside the repository, in the directory $CVSROOT/CVSROOT, there are a number of supportive files for CVS.  You can use CVS in a limited fashion without any of them, but if they are set up properly they can help make life easier.  For a discussion of how to edit them, see Intro administrative files.

The most important of these files is the modules file, which defines the modules inside the repository.

The modules file
================

The modules file records your definitions of names for collections of source code.  CVS will use these definitions if you use CVS to update the modules file (use normal commands like add, commit, etc).

The modules file may contain blank lines and comments (lines beginning with #) as well as module definitions.  Long lines can be continued on the next line by specifying a backslash (\) as the last character on the line.

A module definition is a single line of the modules file, in either of two formats.  In both cases, MNAME represents the symbolic module name, and the remainder of the line is its definition.

MNAME -a ALIASES...
     This represents the simplest way of defining a module MNAME.  The -a flags the definition as a simple alias: CVS will treat any use of MNAME (as a command argument) as if the list of names ALIASES had been specified instead. ALIASES may contain either other module names or paths.  When you use paths in aliases, checkout creates all intermediate directories in the working directory, just as if the path had been specified explicitly in the CVS arguments.

MNAME [ options ] DIR [ FILES... ] [ &MODULE... ]
     In the simplest case, this form of module definition reduces to MNAME DIR.  This defines all the files in directory DIR as module mname. DIR is a relative path (from $CVSROOT) to a directory of source in the source repository.  In this case, on checkout, a single directory called MNAME is created as a working directory; no intermediate directory levels are used by default, even if DIR was a path involving several directory levels.

     By explicitly specifying files in the module definition after DIR, you can select particular files from directory DIR.  The sample definition for modules is an example of a module defined with a single file from a particular directory.  Here is another example:

          m4test  unsupported/gnu/m4 foreach.m4 forloop.m4

     With this definition, executing cvs checkout m4test will create a single working directory m4test containing the two files listed, which both come from a common directory several levels deep in the CVS source repository.

     A module definition can refer to other modules by including &MODULE in its definition. checkout creates a subdirectory for each such module, in your working directory.

     -d NAME
          Name the working directory something other than the module name.

     -e PROG
          Specify a program PROG to run whenever files in a module are exported.  PROG runs with a single argument, the module name.

     -i PROG
          Specify a program PROG to run whenever files in a module are committed.  PROG runs with a single argument, the full pathname of the affected directory in a source repository.  The commitinfo, loginfo, and editinfo files provide other ways to call a program on commit.

     -o PROG
          Specify a program PROG to run whenever files in a module are checked out.  PROG runs with a single argument, the module name.

     -s STATUS
          Assign a status to the module.  When the module file is printed with cvs checkout -s the modules are sorted according to primarily module status, and secondarily according to the module name.  This option has no other meaning.  You can use this option for several things besides status: for instance, list the person that is responsible for this module.

     -t PROG
          Specify a program PROG to run whenever files in a module are tagged with rtag.  PROG runs with two arguments: the module name and the symbolic tag specified to rtag.  There is no way to specify a program to run when tag is executed.

     -u PROG
          Specify a program PROG to run whenever cvs update is executed from the top-level directory of the checked-out module.  PROG runs with a single argument, the full path to the source repository for this module.

The cvswrappers file
====================

Wrappers allow you to set a hook which transforms files on their way in and out of CVS.  Most or all of the wrappers features do not work with client/server CVS.

The file cvswrappers defines the script that will be run on a file when its name matches a regular expresion. There are two scripts that can be run on a file or directory. One script is executed on the file/directory before being checked into the repository (this is denoted with the -t flag) and the other when the file is checked out of the repository (this is denoted with the -f flag)

The cvswrappers also has a -m option to specify the merge methodology that should be used when the file is updated.  MERGE means the usual CVS behavior: try to merge the files (this generally will not work for binary files).  COPY means that cvs update will merely copy one version over the other, and require the user using mechanisms outside CVS, to insert any necessary changes. The -m wrapper option only affects behavior when merging is done on update; it does not affect how files are stored.  See Binary files, for more on binary files.

The basic format of the file cvswrappers is:

     wildcard     [option value][option value]...

     where option is one of
     -f           from cvs filter         value: path to filter
     -t           to cvs filter           value: path to filter
     -m           update methodology      value: MERGE or COPY
     -k           keyword expansion       value: expansion mode

     and value is a single-quote delimited value.

     *.nib    -f 'unwrap %s' -t 'wrap %s %s' -m 'COPY'
     *.c      -t 'indent %s %s'

The above example of a cvswrappers file states that all files/directories that end with a .nib should be filtered with the wrap program before checking the file into the repository. The file should be filtered though the unwrap program when the file is checked out of the repository. The cvswrappers file also states that a COPY methodology should be used when updating the files in the repository (that is no merging should be performed).

The last example line says that all files that end with a *.c should be filtered with indent before being checked into the repository. Unlike the previous example no filtering of the *.c file is done when it is checked out of the repository.

The -t filter is called with two arguments, the first is the name of the file/directory to filter and the second is the pathname to where the resulting filtered file should be placed.

The -f filter is called with one argument, which is the name of the file to filter from. The end result of this filter will be a file in the users directory that they can work on as they normally would.

For another example, the following command imports a directory, treating files whose name ends in .exe as binary:

     cvs import -I ! -W "*.exe -k 'b'" first-dir vendortag reltag

The commit support files
========================

The -i flag in the modules file can be used to run a certain program whenever files are committed (see modules).  The files described in this section provide other, more flexible, ways to run programs whenever something is committed.

There are three kind of programs that can be run on commit.  They are specified in files in the repository, as described below.  The following table summarizes the file names and the purpose of the corresponding programs.

commitinfo
     The program is responsible for checking that the commit is allowed.  If it exits with a non-zero exit status the commit will be aborted.

editinfo
     The specified program is used to edit the log message, and possibly verify that it contains all required fields.  This is most useful in combination with the rcsinfo file, which can hold a log message template (see rcsinfo).

loginfo
     The specified program is called when the commit is complete.  It receives the log message and some additional information and can store the log message in a file, or mail it to appropriate persons, or maybe post it to a local newsgroup, or...  Your imagination is the limit!

The common syntax
-----------------

The four files commitinfo, loginfo, rcsinfo and editinfo all have a common format.  The purpose of the files are described later on.  The common syntax is described here.

Each line contains the following:

  * A regular expression

  * A whitespace separator---one or more spaces and/or tabs.

  * A file name or command-line template.

Blank lines are ignored.  Lines that start with the character # are treated as comments.  Long lines unfortunately can not be broken in two parts in any way.

The first regular expression that matches the current directory name in the repository is used.  The rest of the line is used as a file name or command-line as appropriate.

Commitinfo
==========

The commitinfo file defines programs to execute whenever cvs commit is about to execute.  These programs are used for pre-commit checking to verify that the modified, added and removed files are really ready to be committed.  This could be used, for instance, to verify that the changed files conform to to your site's standards for coding practice.

As mentioned earlier, each line in the commitinfo file consists of a regular expression and a command-line template.  The template can include a program name and any number of arguments you wish to supply to it.  The full path to the current source repository is appended to the template, followed by the file names of any files involved in the commit (added, removed, and modified files).

The first line with a regular expression matching the relative path to the module will be used.  If the command returns a non-zero exit status the commit will be aborted.

If the repository name does not match any of the regular expressions in this file, the DEFAULT line is used, if it is specified.

All occurances of the name ALL appearing as a regular expression are used in addition to the first matching regular expression or the name DEFAULT.

Note: when CVS is accessing a remote repository, commitinfo will be run on the remote (i.e., server) side, not the client side (see Remote repositories).

Editinfo
========

If you want to make sure that all log messages look the same way, you can use the editinfo file to specify a program that is used to edit the log message. This program could be a custom-made editor that always enforces a certain style of the log message, or maybe a simple shell script that calls an editor, and checks that the entered message contains the required fields.

If no matching line is found in the editinfo file, the editor specified in the environment variable $CVSEDITOR is used instead.  If that variable is not set, then the environment variable $EDITOR is used instead.  If that variable is not set a precompiled default, normally vi, will be used.

The editinfo file is often most useful together with the rcsinfo file, which can be used to specify a log message template.

Each line in the editinfo file consists of a regular expression and a command-line template.  The template must include a program name, and can include any number of arguments.  The full path to the current log message template file is appended to the template.

One thing that should be noted is that the ALL keyword is not supported.  If more than one matching line is found, the first one is used.  This can be useful for specifying a default edit script in a module, and then overriding it in a subdirectory.

If the repository name does not match any of the regular expressions in this file, the DEFAULT line is used, if it is specified.

If the edit script exits with a non-zero exit status, the commit is aborted.

Note: when CVS is accessing a remote repository, or when the -m or -F options to cvs commit are used, editinfo will not be consulted. There is no good workaround for this.

Editinfo example
----------------

The following is a little silly example of a editinfo file, together with the corresponding rcsinfo file, the log message template and an editor script.  We begin with the log message template. We want to always record a bug-id number on the first line of the log message.  The rest of log message is free text.  The following template is found in the file /usr/cvssupport/tc.template.

     BugId:

The script /usr/cvssupport/bugid.edit is used to edit the log message.

     #!/bin/sh
     #
     #       bugid.edit filename
     #
     #  Call $EDITOR on FILENAME, and verify that the
     #  resulting file contains a valid bugid on the first
     #  line.
     if [ "x$EDITOR" = "x" ]; then EDITOR=vi; fi
     if [ "x$CVSEDITOR" = "x" ]; then CVSEDITOR=$EDITOR; fi
     $CVSEDITOR $1
     until head -1|grep '^BugId:[ ]*[0-9][0-9]*$' < $1
     do  echo -n  "No BugId found.  Edit again? ([y]/n)"
         read ans
         case ${ans} in
             n*) exit 1;;
         esac
         $CVSEDITOR $1
     done

The editinfo file contains this line:

     ^tc     /usr/cvssupport/bugid.edit

The rcsinfo file contains this line:

     ^tc     /usr/cvssupport/tc.template

Loginfo
=======

The loginfo file is used to control where cvs commit log information is sent.  The first entry on a line is a regular expression which is tested against the directory that the change is being made to, relative to the $CVSROOT.  If a match is found, then the remainder of the line is a filter program that should expect log information on its standard input.

The filter program may use one and only one % modifier (a la printf).  If %s is specified in the filter program, a brief title is included (enclosed in single quotes) showing the modified file names.

If the repository name does not match any of the regular expressions in this file, the DEFAULT line is used, if it is specified.

All occurances of the name ALL appearing as a regular expression are used in addition to the first matching regular expression or DEFAULT.

The first matching regular expression is used.

See commit files, for a description of the syntax of the loginfo file.

Note: when CVS is accessing a remote repository, loginfo will be run on the remote (i.e., server) side, not the client side (see Remote repositories).

Loginfo example
---------------

The following loginfo file, together with the tiny shell-script below, appends all log messages to the file $CVSROOT/CVSROOT/commitlog, and any commits to the administrative files (inside the CVSROOT directory) are also logged in /usr/adm/cvsroot-log.

     ALL             /usr/local/bin/cvs-log $CVSROOT/CVSROOT/commitlog
     ^CVSROOT        /usr/local/bin/cvs-log /usr/adm/cvsroot-log

The shell-script /usr/local/bin/cvs-log looks like this:

     #!/bin/sh
     (echo "-----------------------------------------------------------------";
      echo -n $USER"  ";
      date;
      echo;
      sed '1s+'${CVSROOT}'++') >> $1

Rcsinfo
=======

The rcsinfo file can be used to specify a form to edit when filling out the commit log.  The rcsinfo file has a syntax similar to the editinfo, commitinfo and loginfo files.  See syntax.  Unlike the other files the second part is not a command-line template.  Instead, the part after the regular expression should be a full pathname to a file containing the log message template.

If the repository name does not match any of the regular expressions in this file, the DEFAULT line is used, if it is specified.

All occurances of the name ALL appearing as a regular expression are used in addition to the first matching regular expression or DEFAULT.

The log message template will be used as a default log message.  If you specify a log message with cvs commit -m MESSAGE or cvs commit -f FILE that log message will override the template.

See editinfo example, for an example rcsinfo file.

When CVS is accessing a remote repository, the contents of rcsinfo at the time a directory is first checked out will specify a template which does not then change.  If you edit rcsinfo or its templates, you may need to check out a new working directory.

Ignoring files via cvsignore
============================

There are certain file names that frequently occur inside your working copy, but that you don't want to put under CVS control.  Examples are all the object files that you get while you compile your sources. Normally, when you run cvs update, it prints a line for each file it encounters that it doesn't know about (see update output).

CVS has a list of files (or sh(1) file name patterns) that it should ignore while running update, import and release. This list is constructed in the following way.

  * The list is initialized to include certain file name patterns: names associated with CVS administration, or with other common source control systems; common names for patch files, object files, archive files, and editor backup files; and other names that are usually artifacts of assorted utilities. Currently, the default list of ignored file name patterns is:

              RCS     SCCS    CVS     CVS.adm
              RCSLOG  cvslog.*
              tags    TAGS
              .make.state     .nse_depinfo
              *~      #*      .#*     ,*      _$*     *$
              *.old   *.bak   *.BAK   *.orig  *.rej   .del-*
              *.a     *.olb   *.o     *.obj   *.so    *.exe
              *.Z     *.elc   *.ln
              core

  * The per-repository list in $CVSROOT/CVSROOT/cvsignore is appended to the list, if that file exists.

  * The per-user list in .cvsignore in your home directory is appended to the list, if it exists.

  * Any entries in the environment variable $CVSIGNORE is appended to the list.

  * Any -I options given to CVS is appended.

  * As CVS traverses through your directories, the contents of any .cvsignore will be appended to the list. The patterns found in .cvsignore are only valid for the directory that contains them, not for any sub-directories.

In any of the 5 places listed above, a single exclamation mark (!) clears the ignore list. This can be used if you want to store any file which normally is ignored by CVS.

The history file
================

The file $CVSROOT/CVSROOT/history is used to log information for the history command (see history).  This file must be created to turn on logging.  This is done automatically if the cvs init command is used to set up the repository (see Creating a repository).

The file format of the history file is documented only in comments in the CVS source code, but generally programs should use the cvs history command to access it anyway, in case the format changes with future releases of CVS.

Expansions in administrative files
==================================

Sometimes in writing an administrative file, you might want the file to be able to know various things based on environment CVS is running in.  There are several mechanisms to do that.

To find the home directory of the user running CVS (from the HOME environment variable), use ~ followed by / or the end of the line. Likewise for the home directory of USER, use ~USER.  These variables are expanded on the server machine, and don't get any resonable expansion if pserver (see Password authenticated) is in used; therefore user variables (see below) may be a better choice to customize behavior based on the user running CVS.

One may want to know about various pieces of information internal to CVS.  A CVS internal variable has the syntax ${VARIABLE}, where VARIABLE starts with a letter and consists of alphanumberic characters and _.  If the character following VARIABLE is a non-alphanumeric character other than _, the { and } can be omitted.  The CVS internal variables are:

CVSROOT
     This is the value of the CVS root in use. See Repository, for a description of the various ways to specify this.

RCSBIN
     This is the value CVS is using for where to find RCS binaries.  See Global options, for a description of how to specify this.

CVSEDITOR
VISUAL
EDITOR
     These all expand to the same value, which is the editor that CVS is using.  See Global options, for how to specify this.

USER
     Username of the user running CVS (on the CVS server machine).

If you want to pass a value to the administrative files which the user that is running CVS can specify, use a user variable.  To expand a user variable, the administrative file contains ${=VARIABLE}.  To set a user variable, specify the global option -s to CVS, with argument VARIABLE=VALUE.  It may be particularly useful to specify this option via .cvsrc (see ~/.cvsrc).

For example, if you want the administrative file to refer to a test directory you might create a user variable TESTDIR.  Then if CVS is invoked as cvs -s TESTDIR=/work/local/tests, and the administrative file contains sh ${=TESTDIR}/runtests, then that string is expanded to sh /work/local/tests/runtests.

All other strings containing $ are reserved; there is no way to quote a $ character so that $ represents itself.

All environment variables which affect CVS
******************************************

This is a complete list of all environment variables that affect CVS.

$CVSIGNORE
     A whitespace-separated list of file name patterns that CVS should ignore. See cvsignore.

$CVSWRAPPERS
     A whitespace-separated list of file name patterns that CVS should treat as wrappers. See Wrappers.

$CVSREAD
     If this is set, checkout and update will try hard to make the files in your working directory read-only.  When this is not set, the default behavior is to permit modification of your working files.

$CVSROOT
     Should contain the full pathname to the root of the CVS source repository (where the RCS history files are kept).  This information must be available to CVS for most commands to execute; if $CVSROOT is not set, or if you wish to override it for one invocation, you can supply it on the command line: cvs -d cvsroot cvs_command... Once you have checked out a working directory, CVS stores the appropriate root (in the file CVS/Root), so normally you only need to worry about this when initially checking out a working directory.

$EDITOR
$CVSEDITOR
     Specifies the program to use for recording log messages during commit.  If not set, the default is /usr/ucb/vi.  $CVSEDITOR overrides $EDITOR.  $CVSEDITOR does not exist in CVS 1.3, but the next release will probably include it.

$PATH
     If $RCSBIN is not set, and no path is compiled into CVS, it will use $PATH to try to find all programs it uses.

$RCSBIN
     Specifies the full pathname of the location of RCS programs, such as co(1) and ci(1).  If not set, a compiled-in value is used, or your $PATH is searched.

$HOME

$HOMEPATH
     Used to locate the directory where the .cvsrc file is searched ($HOMEPATH is used for Windows-NT). see ~/.cvsrc

$CVS_RSH
     Used in client-server mode when accessing a remote repository using RSH.  The default value is rsh.  You can set it to use another program for accssing the remote server (e.g. for HP-UX 9, you should set it to remsh because rsh invokes the restricted shell).  see Connecting via rsh

$CVS_SERVER
     Used in client-server mode when accessing a remote repository using RSH.  It specifies the name of the program to start on the server side when accessing a remote repository using RSH.  The default value is cvs.  see Connecting via rsh

$CVS_PASSFILE
     Used in client-server mode when accessing the cvs login server.  Default value is $HOME/.cvspass. see Password authentication client

$CVS_PASSWORD
     Used in client-server mode when accessing the cvs login server. see Password authentication client

$CVS_CLIENT_PORT
     Used in client-server mode when accessing the server via Kerberos. see Kerberos authenticated

$CVS_RCMD_PORT
     Used in client-server mode.  If set, specifies the port number to be used when accessing the RCMD demon on the server side. (Currently not used for Unix clients).

$CVS_CLIENT_LOG
     Used for debugging only in client-server mode.  If set, everything send to the server is logged into $CVS_CLIENT_LOG.in and everything send from the server is logged into $CVS_CLIENT_LOG.out.

$CVS_SERVER_SLEEP
     Used only for debugging the server side in client-server mode.  If set, delays the start of the server child process the the specified amount of seconds so that you can attach to it with a debugger.

$CVS_IGNORE_REMOTE_ROOT
     (What is the purpose of this variable?)

$COMSPEC
     Used under OS/2 only.  It specifies the name of the command interpreter and defaults to CMD.EXE.

$TMPDIR
$TMP
$TEMP
     Directory in which temporary files are located.  Those parts of CVS which are implemented using RCS inspect the above variables in the order they appear above and the first value found is taken; if none of them are set, a host-dependent default is used, typically /tmp.  The CVS server checks TMPDIR, and if not set, it uses /tmp. Some parts of CVS will always use /tmp (via the tmpnam function provided by the system).

     On Windows NT, TMP is used (via the _tempnam function provided by the system).

     The patch program which is used by the CVS client uses TMPDIR, and if it is not set, uses /tmp (at least with GNU patch 2.1).

CVS invokes RCS to perform certain operations.  The following environment variables affect RCS.  Note that if you are using the client/server CVS, these variables need to be set on the server side (which may or not may be possible depending on how you are connecting).  There is probably not any need to set any of them, however.

$LOGNAME
$USER
     If set, they affect who RCS thinks you are.  If you have trouble checking in files it might be because your login name differs from the setting of e.g. $LOGNAME.

$RCSINIT
     Options prepended to the argument list, separated by spaces.  A backslash escapes spaces within an option. The $RCSINIT options are prepended to the argument lists of most RCS commands.

Troubleshooting
***************

Magic branch numbers
====================

Externally, branch numbers consist of an odd number of dot-separated decimal integers.  See Revision numbers.  That is not the whole truth, however.  For efficiency reasons CVS sometimes inserts an extra 0 in the second rightmost position (1.2.3 becomes 1.2.0.3, 8.9.10.11.12 becomes 8.9.10.11.0.12 and so on).

CVS does a pretty good job at hiding these so called magic branches, but in at least four places the hiding is incomplete.

  * The magic branch can appear in the output from cvs status in vanilla CVS 1.3.  This is fixed in CVS 1.3-s2.

  * The magic branch number appears in the output from cvs log.  This is much harder to fix, since cvs log runs rlog (which is part of the RCS distribution), and modifying rlog to know about magic branches would probably break someone's habits (if they use branch 0 for their own purposes).

  * You cannot specify a symbolic branch name to cvs log.

  * You cannot specify a symbolic branch name to cvs admin.

You can use the admin command to reassign a symbolic name to a branch the way RCS expects it to be.  If R4patches is assigned to the branch 1.4.2 (magic branch number 1.4.0.2) in file numbers.c you can do this:

     $ cvs admin -NR4patches:1.4.2 numbers.c

It only works if at least one revision is already committed on the branch.  Be very careful so that you do not assign the tag to the wrong number.  (There is no way to see how the tag was assigned yesterday).

GNU GENERAL PUBLIC LICENSE
**************************