Version Management
with
CVS
for CVS 1.9.29
Per Cederqvist et al
Copyright (C) 1992, 1993 Signum Support AB
Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.
Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.
Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Free Software Foundation.
This chapter is for people who have never used CVS, and perhaps have never used version control software before.
If you are already familiar with CVS and are just trying to learn a particular feature or remember a certain command, you can probably skip everything here.
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 the newsgroup
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 in a variety of ways, including free download from the internet. For more information on downloading CVS and other CVS topics, see:
http://www.cyclic.com/ http://www.loria.fr/~molli/cvs-index.html
There is a mailing list, known as info-cvs,
devoted to CVS. To subscribe or
unsubscribe
write to
info-cvs-request@gnu.org.
If you prefer a usenet group, the right
group is comp.software.config-mgmt which is for
CVS discussions (along with other configuration
management systems). In the future, it might be
possible to create a
comp.software.config-mgmt.cvs, but probably only
if there is sufficient CVS traffic on
comp.software.config-mgmt.
You can also subscribe to the bug-cvs mailing list, described in more detail in section Dealing with bugs in CVS or this manual. To subscribe send mail to bug-cvs-request@gnu.org.
CVS can do a lot of things for you, but it does not try to be everything for everyone.
VPATH in `Makefile's, 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, `Makefile's,
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 dependencies which
make uses.
See section How your build system interacts with CVS, for more information on doing builds
in conjunction with CVS.
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 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.
commitinfo file. I haven't
heard a lot about projects trying to do that or whether
there are subtle gotchas, however.
As a way of introducing CVS, we'll go through a typical work-session using CVS. The first thing to understand is that CVS stores all files in a centralized repository (see section The Repository); this section assumes that a repository is set up.
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'.
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 section Multiple developers, for an explanation.
When you have checked that the compiler is still compilable you decide to make a new version of `backend.c'. This will store your new `backend.c' in the repository and make it available to anyone else who is using that same repository.
$ 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 there is a default
which will vary with your operating system, for example
vi for unix or notepad for Windows
NT/95.
When CVS starts the editor, it includes a list of
files which are modified. For the CVS client,
this list is based on comparing the modification time
of the file against the modification time that the file
had when it was last gotten or updated. Therefore, if
a file's modification time has changed but its contents
have not, it will show up as modified. The simplest
way to handle this is simply not to worry about it--if
you proceed with the commit CVS will detect that
the contents are not modified and treat it as an
unmodified file. The next update will clue
CVS in to the fact that the file is unmodified,
and it will reset its stored timestamp so that the file
will not show up in future editor sessions.
If you want to avoid 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
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 section release--Indicate that a Module is no longer in use):
$ 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 section The 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 section Ignoring files via cvsignore,
for information about how to make that warning go away.
See section 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.
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 CVS repository stores a complete copy of all the files and directories which are under version control.
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 into a working directory, and then work on that copy. When you've finished a set of changes, you check (or commit) them back into the repository. The repository then contains the changes which you have made, as well as recording exactly what you changed, when you changed it, and other such information. Note that the repository is not a subdirectory of the working directory, or vice versa; they should be in separate locations.
CVS can access a repository by a variety of
means. It might be on the local computer, or it might
be on a computer across the room or across the world.
To distinguish various ways to access a repository, the
repository name can start with an access method.
For example, the access method :local: means to
access a repository directory, so the repository
:local:/usr/local/cvsroot means that the
repository is in `/usr/local/cvsroot' on the
computer running CVS. For information on other
access methods, see section Remote repositories.
If the access method is omitted, then if the repository
does not contain `:', then :local: is
assumed. If it does contain `:' then either
:ext: or :server: is assumed. For
example, if you have a local repository in
`/usr/local/cvsroot', you can use
/usr/local/cvsroot instead of
:local:/usr/local/cvsroot. But if (under
Windows NT, for example) your local repository is
`c:\src\cvsroot', then you must specify the access
method, as in :local:c:\src\cvsroot.
The repository is split in two parts. `$CVSROOT/CVSROOT' contains administrative files for CVS. The other directories contain the actual user-defined modules.
There are several 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, 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.
For most purposes it isn't important how CVS stores information in the repository. In fact, the format has changed in the past, and is likely to change in the future. Since in almost all cases one accesses the repository via CVS commands, such changes need not be disruptive.
However, in some cases it may be necessary to understand how CVS stores data in the repository, for example you might need to track down CVS locks (see section Several developers simultaneously attempting to run CVS) or you might need to deal with the file permissions appropriate for the repository.
The overall structure of the repository is a directory tree corresponding to the directories in the working directory. For example, supposing the repository is in
/usr/local/cvsroot
here is a possible directory tree (showing only the directories):
/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)
With the directories are history files for each file under version control. The name of the history file is the name of the corresponding file with `,v' appended to the end. Here is what the repository for the `yoyodyne/tc' directory might look like:
$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 history files 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. The history files are
known as RCS files, because the first program to
store files in that format was a version control system
known as RCS. For a full
description of the file format, see the man page
rcsfile(5), distributed with RCS, or the
file `doc/RCSFILES' in the CVS source
distribution. This
file format has become very common--many systems other
than CVS or RCS can at least import history
files in this format.
The RCS files used in CVS differ in a few ways from the standard format. The biggest difference is magic branches; for more information see section Magic branch numbers. Also in CVS the valid tag names are a subset of what RCS accepts; for CVS's rules see section Tags--Symbolic revisions.
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.
Note that users must also have write access to check out files, because CVS needs to create lock files (see section Several developers simultaneously attempting to run CVS).
Also note that users must have write access to the `CVSROOT/val-tags' file. CVS uses it to keep track of what tags are valid tag names (it is sometimes updated when tags are used, as well as when they are created).
Each RCS file will be owned by the user who last checked it in. This has little significance; what really matters is who owns the directories.
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. If you set the CVSUMASK
environment variable that will control the file
permissions which CVS uses in creating directories
and/or files in the repository. CVSUMASK does
not affect the file permissions in the working
directory; such files have the permissions which are
typical for newly created files, except that sometimes
CVS creates them read-only (see the sections on
watches, section Telling CVS to watch certain files; -r, section Global options; or CVSREAD, section All environment variables which affect CVS).
Note that using the client/server CVS
(see section Remote repositories), there is no good way to
set CVSUMASK; the setting on the client machine
has no effect. If you are connecting with rsh, you
can set CVSUMASK in `.bashrc' or `.cshrc', as
described in the documentation for your operating
system. This behavior might change in future versions
of CVS; do not rely on the setting of
CVSUMASK on the client having no effect.
Using pserver, you will generally need stricter permissions on the CVSROOT directory and directories above it in the tree; see section Security considerations with password authentication.
Some operating systems have features which allow a particular program to run with the ability to perform operations which the caller of the program could not. For example, the set user ID (setuid) or set group ID (setgid) features of unix or the installed image feature of VMS. CVS was not written to use such features and therefore attempting to install CVS in this fashion will provide protection against only accidental lapses; anyone who is trying to circumvent the measure will be able to do so, and depending on how you have set it up may gain access to more than just CVS. You may wish to instead consider pserver. It shares some of the same attributes, in terms of possibly providing a false sense of security or opening security holes wider than the ones you are trying to fix, so read the documentation on pserver security carefully if you are considering this option (section Security considerations with password authentication).
Some file permission issues are specific to Windows operating systems (Windows 95, Windows NT, and presumably future operating systems in this family. Some of the following might apply to OS/2 but I'm not sure).
If you are using local CVS and the repository is on a networked file system which is served by the Samba SMB server, some people have reported problems with permissions. Enabling WRITE=YES in the samba configuration is said to fix/workaround it. Disclaimer: I haven't investigated enough to know the implications of enabling that option, nor do I know whether there is something which CVS could be doing differently in order to avoid the problem. If you find something out, please let us know as described in section Dealing with bugs in CVS or this manual.
You will notice that sometimes CVS stores an
RCS file in the Attic. For example, if the
CVSROOT is `/usr/local/cvsroot' and we are
talking about the file `backend.c' in the
directory `yoyodyne/tc', then the file normally
would be in
/usr/local/cvsroot/yoyodyne/tc/backend.c,v
but if it goes in the attic, it would be in
/usr/local/cvsroot/yoyodyne/tc/Attic/backend.c,v
instead. It should not matter from a user point of
view whether a file is in the attic; CVS keeps
track of this and looks in the attic when it needs to.
But in case you want to know, the rule is that the RCS
file is stored in the attic if and only if the head
revision on the trunk has state dead. A
dead state means that file has been removed, or
never added, for that revision. For example, if you
add a file on a branch, it will have a trunk revision
in dead state, and a branch revision in a
non-dead state.
The `CVS' directory in each repository directory contains information such as file attributes (in a file called `CVS/fileattr'; see fileattr.h in the CVS source distribution for more documentation). In the future additional files may be added to this directory, so implementations should silently ignore additional files.
This behavior is implemented only by CVS 1.7 and later; for details see section Using watches with old versions of CVS.
For an introduction to CVS locks focusing on user-visible behavior, see section Several developers simultaneously attempting to run CVS. The following section is aimed at people who are writing tools which want to access a CVS repository without interfering with other tools accessing the same repository. If you find yourself confused by concepts described here, like read lock, write lock, and deadlock, you might consult the literature on operating systems or databases.
Any file in the repository with a name starting with `#cvs.rfl' is a read lock. Any file in the repository with a name starting with `#cvs.wfl' is a write lock. Old versions of CVS (before CVS 1.5) also created files with names starting with `#cvs.tfl', but they are not discussed here. The directory `#cvs.lock' serves as a master lock. That is, one must obtain this lock first before creating any of the other locks.
To obtain a readlock, first create the `#cvs.lock' directory. This operation must be atomic (which should be true for creating a directory under most operating systems). If it fails because the directory already existed, wait for a while and try again. After obtaining the `#cvs.lock' lock, create a file whose name is `#cvs.rfl' followed by information of your choice (for example, hostname and process identification number). Then remove the `#cvs.lock' directory to release the master lock. Then proceed with reading the repository. When you are done, remove the `#cvs.rfl' file to release the read lock.
To obtain a writelock, first create the `#cvs.lock' directory, as with a readlock. Then check that there are no files whose names start with `#cvs.rfl'. If there are, remove `#cvs.lock', wait for a while, and try again. If there are no readers, then create a file whose name is `#cvs.wfl' followed by information of your choice (for example, hostname and process identification number). Hang on to the `#cvs.lock' lock. Proceed with writing the repository. When you are done, first remove the `#cvs.wfl' file and then the `#cvs.lock' directory. Note that unlike the `#cvs.rfl' file, the `#cvs.wfl' file is just informational; it has no effect on the locking operation beyond what is provided by holding on to the `#cvs.lock' lock itself.
Note that each lock (writelock or readlock) only locks a single directory in the repository, including `Attic' and `CVS' but not including subdirectories which represent other directories under version control. To lock an entire tree, you need to lock each directory (note that if you fail to obtain any lock you need, you must release the whole tree before waiting and trying again, to avoid deadlocks).
Note also that CVS expects writelocks to control access to individual `foo,v' files. RCS has a scheme where the `,foo,' file serves as a lock, but CVS does not implement it and so taking out a CVS writelock is recommended. See the comments at rcs_internal_lockfile in the CVS source code for further discussion/rationale.
The `$CVSROOT/CVSROOT' directory contains the various administrative files. In some ways this directory is just like any other directory in the repository; it contains RCS files whose names end in `,v', and many of the CVS commands operate on it the same way. However, there are a few differences.
For each administrative file, in addition to the RCS file, there is also a checked out copy of the file. For example, there is an RCS file `loginfo,v' and a file `loginfo' which contains the latest revision contained in `loginfo,v'. When you check in an administrative file, CVS should print
cvs commit: Rebuilding administrative file database
and update the checked out copy in `$CVSROOT/CVSROOT'. If it does not, there is something wrong (see section Dealing with bugs in CVS or this manual). To add your own files to the files to be updated in this fashion, you can add them to the `checkoutlist' administrative file.
By default, the `modules' file behaves as
described above. If the modules file is very large,
storing it as a flat text file may make looking up
modules slow (I'm not sure whether this is as much of a
concern now as when CVS first evolved this
feature; I haven't seen benchmarks). Therefore, by
making appropriate edits to the CVS source code
one can store the modules file in a database which
implements the ndbm interface, such as Berkeley
db or GDBM. If this option is in use, then the modules
database will be stored in the files `modules.db',
`modules.pag', and/or `modules.dir'.
For information on the meaning of the various administrative files, see section Reference manual for Administrative files.
While we are discussing CVS internals which may
become visible from time to time, we might as well talk
about what CVS puts in the `CVS' directories
in the working directories. As with the repository,
CVS handles this information and one can usually
access it via CVS commands. But in some cases it
may be useful to look at it, and other programs, such
as the jCVS graphical user interface or the
VC package for emacs, may need to look at it.
Such programs should follow the recommendations in this
section if they hope to be able to work with other
programs which use those files, including future
versions of the programs just mentioned and the
command-line CVS client.
The `CVS' directory contains several files. Programs which are reading this directory should silently ignore files which are in the directory but which are not documented here, to allow for future expansion.
cvs -d :local:/usr/local/cvsroot checkout yoyodyne/tc`Root' will contain
:local:/usr/local/cvsrootand `Repository' will contain either
/usr/local/cvsroot/yoyodyne/tcor
yoyodyne/tc
/name/revision/timestamp[+conflict]/options/tagdatewhere `[' and `]' are not part of the entry, but instead indicate that the `+' and conflict marker are optional. name is the name of the file within the directory. revision is the revision that the file in the working derives from, or `0' for an added file, or `-' followed by a revision for a removed file. timestamp is the timestamp of the file at the time that CVS created it; if the timestamp differs with the actual modification time of the file it means the file has been modified. It is in Universal Time (UT), stored in the format used by the ISO C asctime() function (for example, `Sun Apr 7 01:29:26 1996'). One may write a string which is not in that format, for example, `Result of merge', to indicate that the file should always be considered to be modified. This is not a special case; to see whether a file is modified a program should take the timestamp of the file and simply do a string compare with timestamp. conflict indicates that there was a conflict; if it is the same as the actual modification time of the file it means that the user has obviously not resolved the conflict. options contains sticky options (for example `-kb' for a binary file). tagdate contains `T' followed by a tag name, or `D' for a date, followed by a sticky tag or date. Note that if timestamp contains a pair of timestamps separated by a space, rather than a single timestamp, you are dealing with a version of CVS earlier than CVS 1.5 (not documented here). If the first character of a line in `Entries' is `D', then it indicates a subdirectory. `D' on a line all by itself indicates that the program which wrote the `Entries' file does record subdirectories (therefore, if there is such a line and no other lines beginning with `D', one knows there are no subdirectories). Otherwise, the line looks like:
D/name/filler1/filler2/filler3/filler4where name is the name of the subdirectory, and all the filler fields should be silently ignored, for future expansion. Programs which modify
Entries files should preserve these fields.
update command with the
`-d' option, which will get the additional files
and remove `Entries.Static'.
edit or unedit) which have not yet been
sent to the server. Its format is not yet documented
here.
edit command
stores the original copy of the file in the `Base'
directory. This allows the unedit command to
operate even if it is unable to communicate with the
server.
Bname/rev/expansionwhere expansion should be ignored, to allow for future expansion.
The directory `$CVSROOT/CVSROOT' contains some administrative files. See section Reference manual for 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 section The modules file, for a full explanation of all the available features.
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.
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 section Telling CVS where your repository is).
The big advantage of having multiple repositories is that they can reside on different servers. The big disadvantage is that you cannot have a single CVS command recurse into directories which comes from different repositories. Generally speaking, if you are thinking of setting up several repositories on the same machine, you might want to consider using several directories within the same repository.
None of the examples in this manual show multiple repositories.
To set up a CVS repository, first choose the machine and disk on which you want to store the revision history of the source files. CPU and memory requirements are modest, so most machines should be adequate. For details see section Server requirements.
To estimate disk space requirements, if you are importing RCS files from another system, the size of those files is the approximate initial size of your repository, or if you are starting without any version history, a rule of thumb is to allow for the server approximately three times the size of the code to be under CVS for the repository (you will eventually outgrow this, but not for a while). On the machines on which the developers will be working, you'll want disk space for approximately one working directory for each developer (either the entire tree or a portion of it, depending on what each developer uses).
The repository should be accessible (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 section Several developers simultaneously attempting to run CVS).
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 section The 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 section The history file.
There is nothing particularly magical about the files in the repository; for the most part it is possible to back them up just like any other files. However, there are a few issues to consider.
The first is that to be paranoid, one should either not use CVS during the backup, or have the backup program lock CVS while doing the backup. To not use CVS, you might forbid logins to machines which can access the repository, turn off your CVS server, or similar mechanisms. The details would depend on your operating system and how you have CVS set up. To lock CVS, you would create `#cvs.rfl' locks in each repository directory. See section Several developers simultaneously attempting to run CVS, for more on CVS locks. Having said all this, if you just back up without any of these precautions, the results are unlikely to be particularly dire. Restoring from backup, the repository might be in an inconsistent state, but this would not be particularly hard to fix manually.
When you restore a repository from backup, assuming that changes in the repository were made after the time of the backup, working directories which were not affected by the failure may refer to revisions which no longer exist in the repository. Trying to run CVS in such directories will typically produce an error message. One way to get those changes back into the repository is as follows:
cvs update and cvs diff to figure out
what has changed, and then when you are ready, commit
the changes into the repository.
Just as backing up the files in the repository is pretty much like backing up any other files, if you need to move a repository from one place to another it is also pretty much like just moving any other collection of files.
The main thing to consider is that working directories point to the repository. The simplest way to deal with a moved repository is to just get a fresh working directory after the move. Of course, you'll want to make sure that the old working directory had been checked in before the move, or you figured out some other way to make sure that you don't lose any changes. If you really do want to reuse the existing working directory, it should be possible with manual surgery on the `CVS/Repository' files. You can see section How data is stored in the working directory, for information on the `CVS/Repository' and `CVS/Root' files, but unless you are sure you want to bother, it probably isn't worth it.
Your working copy of the sources can be on a different machine than the repository. Using CVS in this manner is known as client/server operation. You run CVS on a machine which can mount your working directory, known as the client, and tell it to communicate to a machine which can mount the repository, known as the server. 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.
If method is not specified, and the repository
name contains `:', then the default is ext
or server, depending on your platform; both are
described in section Connecting with rsh.
The quick answer to what sort of machine is suitable as a server is that requirements are modest--a server with 32M of memory or even less can handle a fairly large source tree with a fair amount of activity.
The real answer, of course, is more complicated. Estimating the known areas of large memory consumption should be sufficient to estimate memory requirements. There are two such areas documented here; other memory consumption should be small by comparison (if you find that is not the case, let us know, as described in section Dealing with bugs in CVS or this manual, so we can update this documentation).
The first area of big memory consumption is large checkouts, when using the CVS server. The server consists of two processes for each client that it is serving. Memory consumption on the child process should remain fairly small. Memory consumption on the parent process, particularly if the network connection to the client is slow, can be expected to grow to slightly more than the size of the sources in a single directory, or two megabytes, whichever is larger.
Multiplying the size of each CVS server by the number of servers which you expect to have active at one time should give an idea of memory requirements for the server. For the most part, the memory consumed by the parent process probably can be swap space rather than physical memory.
The second area of large memory consumption is
diff, when checking in large files. This is
required even for binary files. The rule of thumb is
to allow about ten times the size of the largest file
you will want to check in, although five times may be
adequate. For example, if you want to check in a file
which is 10 megabytes, you should have 100 megabytes of
memory on the machine doing the checkin (the server
machine for client/server, or the machine running
CVS for non-client/server). This can be swap
space rather than physical memory. Because the memory
is only required briefly, there is no particular need
to allow memory for more than one such checkin at a
time.
Resource consumption for the client is even more modest--any machine with enough capacity to run the operating system in question should have little trouble.
For information on disk space requirements, see section Creating a repository.
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 `toe.grunge.com', and the server machine is `chainsaw.yard.com'. On chainsaw, put the following line into the file `.rhosts' in `bach''s home directory:
toe.grunge.com mozart
Then test that rsh is working with
rsh -l bach chainsaw.yard.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.
There are two access methods that you use in CVSROOT
for rsh. :server: specifies an internal rsh
client, which is supported only by some CVS ports.
:ext: specifies an external rsh program. By
default this is rsh but you may set the
CVS_RSH environment variable to invoke another
program which can access the remote server (for
example, remsh on HP-UX 9 because rsh is
something different). It must be a program which can
transmit data to and from the server without modifying
it; for example the Windows NT rsh is not
suitable since it by default translates between CRLF
and LF. The OS/2 CVS port has a hack to pass `-b'
to rsh to get around this, but since this could
potentially cause problems for programs other than the
standard rsh, it may change in the future. If
you set CVS_RSH to SSH or some other rsh
replacement, the instructions in the rest of this
section concerning `.rhosts' and so on are likely
to be inapplicable; consult the documentation for your rsh
replacement.
Continuing our example, supposing you want to access the module `foo' in the repository `/usr/local/cvsroot/', on machine `chainsaw.yard.com', you are ready to go:
cvs -d :ext:bach@chainsaw.yard.com:/usr/local/cvsroot checkout foo
(The `bach@' can be omitted if the username is the same on both the local and remote hosts.)
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.
First of all, you probably want to tighten the permissions on the `$CVSROOT' and `$CVSROOT/CVSROOT' directories. See section Security considerations with password authentication, for more details.
On the server side, the file `/etc/inetd.conf'
needs to be edited so inetd knows to run the
command cvs pserver when it receives a
connection on the right port. By default, the port
number is 2401; it would be different if your client
were compiled with CVS_AUTH_PORT defined to
something else, though.
If your inetd allows raw port numbers in
`/etc/inetd.conf', then the following (all on a
single line in `inetd.conf') should be sufficient:
2401 stream tcp nowait root /usr/local/bin/cvs cvs --allow-root=/usr/cvsroot pserver
You could also use the `-T' option to specify a temporary directory.
The `--allow-root' option specifies the allowable CVSROOT directory. Clients which attempt to use a different CVSROOT directory will not be allowed to connect. If there is more than one CVSROOT directory which you want to allow, repeat the option.
If your inetd wants a symbolic service
name instead of a raw port number, then put this in
`/etc/services':
cvspserver 2401/tcp
and put cvspserver instead of
2401 in `inetd.conf'.
Once the above is taken care of, restart your
inetd, or do whatever is necessary to force it
to reread its initialization files.
Because the client stores and transmits passwords in cleartext (almost--see section Security considerations with password authentication, for details), a separate CVS password file may be used, so people don't compromise their regular passwords when they access the repository. This file is `$CVSROOT/CVSROOT/passwd' (see section The administrative files). Its format is similar to `/etc/passwd', except that it only has two or three fields, username, password, and optional username for the server to use. 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 (using the system's user-lookup
routine can be disabled by setting SystemAuth=no
in the config file, see section The CVSROOT/config configuration file). When using the CVS
`passwd' file, the server runs as the
username specified in 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.
It is possible to "map" cvs-specific usernames onto system usernames (i.e., onto system login names) in the `$CVSROOT/CVSROOT/passwd' file by appending a colon and the system username after the password. For example:
cvs:ULtgRLXo7NRxs:kfogel generic:1sOp854gDF3DY:spwang anyone:1sOp854gDF3DY:spwang
Thus, someone remotely accessing the repository on `chainsaw.yard.com' with the following command:
cvs -d :pserver:cvs@chainsaw.yard.com:/usr/local/cvsroot checkout foo
would end up running the server under the system identity kfogel, assuming successful authentication. However, the remote user would not necessarily need to know kfogel's system password, as the `$CVSROOT/CVSROOT/passwd' file might contain a different password, used only for CVS. And as the example above indicates, it is permissible to map multiple cvs usernames onto a single system username.
This feature is designed to allow people repository access without full system access (in particular, see section Read-only repository access); however, also see section Security considerations with password authentication. Any sort of repository access very likely implies a degree of general system access as well.
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.
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.yard.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.yard.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 section Connecting with 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 `$HOME/.cvspass'. Its format is human-readable, but don't edit it unless you know what you are doing. The passwords are not stored in cleartext, but are trivially encoded to protect them from "innocent" compromise (i.e., inadvertently being seen by a system administrator who happens to look at that file).
The password for the currently choosen remote repository
can be removed from the CVS_PASSFILE by using the
cvs logout command.
The CVS_PASSFILE environment variable overrides
this default. If you use this variable, make sure you
set it before cvs login is run. If you
were to set it after running cvs login, then
later CVS commands would be unable to look up the
password for transmission to the server.
The passwords are stored on the client side in a trivial encoding of the cleartext, and transmitted in the same encoding. The encoding is done only to prevent inadvertent password compromises (i.e., a system administrator accidentally looking at the file), and will not prevent even a naive attacker from gaining the password.
The separate CVS password file (see section Setting up the server for password authentication) allows people to use a different password for repository access than for login access. On the other hand, once a user has non-read-only access to the repository, she can execute programs on the server system through a variety of means. Thus, repository access implies fairly broad system access as well. It might be possible to modify CVS to prevent that, but no one has done so as of this writing. Furthermore, there may be other ways in which having access to CVS allows people to gain more general access to the system; no one has done a careful audit.
Note that because the `$CVSROOT/CVSROOT' directory contains `passwd' and other files which are used to check security, you must control the permissions on this directory as tightly as the permissions on `/etc'. The same applies to the `$CVSROOT' directory itself and any directory above it in the tree. Anyone who has write access to such a directory will have the ability to become any user on the system. Note that these permissions are typically tighter than you would use if you are not using pserver.
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.
GSSAPI is a generic interface to network security systems such as Kerberos 5. If you have a working GSSAPI library, you can have CVS connect via a direct TCP connection, authenticating with GSSAPI.
To do this, CVS needs to be compiled with GSSAPI support; when configuring CVS it tries to detect whether GSSAPI libraries using kerberos version 5 are present. You can also use the `--with-gssapi' flag to configure.
The connection is authenticated using GSSAPI, but the
message stream is not authenticated by default.
You must use the -a global option to request
stream authentication.
The data transmitted is not encrypted by
default. Encryption support must be compiled into both
the client and the server; use the
`--enable-encrypt' configure option to turn it on.
You must then use the -x global option to
request encryption.
GSSAPI connections are handled on the server side by
the same server which handles the password
authentication server; see section Setting up the server for password authentication. If you are using a GSSAPI mechanism such as
Kerberos which provides for strong authentication, you
will probably want to disable the ability to
authenticate via cleartext passwords. To do so, create
an empty `CVSROOT/passwd' password file, and set
SystemAuth=no in the config file
(see section The CVSROOT/config configuration file).
The GSSAPI server uses a principal name of cvs/hostname, where hostname is the canonical name of the server host. You will have to set this up as required by your GSSAPI mechanism.
To connect using GSSAPI, use `:gserver:'. For example,
cvs -d :gserver:chainsaw.yard.com:/usr/local/cvsroot checkout foo
The easiest way to use kerberos is to use the kerberos
rsh, as described in section Connecting with rsh.
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.
This section concerns the kerberos network security system, version 4. Kerberos version 5 is supported via the GSSAPI generic network security interface, as described in the previous section.
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.
The data transmitted is not encrypted by
default. Encryption support must be compiled into both
the client and server; use the
`--enable-encryption' configure option to turn it
on. You must then use the -x global option to
request encryption.
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.yard.com:/usr/local/cvsroot checkout foo
Previous versions of CVS would fall back to a connection via rsh; this version will not do so.
It is possible to grant read-only repository access to people using the password-authenticated server (see section Direct connection with password authentication). (The other access methods do not have explicit support for read-only users because those methods all assume login access to the repository machine anyway, and therefore the user can do whatever local file permissions allow her to do.)
A user who has read-only access can do only those CVS operations which do not modify the repository, except for certain "administrative" files (such as lock files and the history file). It may be desirable to use this feature in conjunction with user-aliasing (see section Setting up the server for password authentication).
Unlike with previous versions of CVS, read-only users should be able merely to read the repository, and not to execute programs on the server or otherwise gain unexpected levels of access. Or to be more accurate, the known holes have been plugged. Because this feature is new and has not received a comprehensive security audit, you should use whatever level of caution seems warranted given your attitude concerning security.
There are two ways to specify read-only access for a user: by inclusion, and by exclusion.
"Inclusion" means listing that user specifically in the `$CVSROOT/CVSROOT/readers' file, which is simply a newline-separated list of users. Here is a sample `readers' file:
melissa splotnik jrandom
(Don't forget the newline after the last user.)
"Exclusion" means explicitly listing everyone who has write access--if the file
$CVSROOT/CVSROOT/writers
exists, then only those users listed in it have write access, and everyone else has read-only access (of course, even the read-only users still need to be listed in the CVS `passwd' file). The `writers' file has the same format as the `readers' file.
Note: if your CVS `passwd' file maps cvs users onto system users (see section Setting up the server for password authentication), make sure you deny or grant read-only access using the cvs usernames, not the system usernames. That is, the `readers' and `writers' files contain cvs usernames, which may or may not be the same as system usernames.
Here is a complete description of the server's behavior in deciding whether to grant read-only or read-write access:
If `readers' exists, and this user is listed in it, then she gets read-only access. Or if `writers' exists, and this user is NOT listed in it, then she also gets read-only access (this is true even if `readers' exists but she is not listed there). Otherwise, she gets full read-write access.
Of course there is a conflict if the user is listed in both files. This is resolved in the more conservative way, it being better to protect the repository too much than too little: such a user gets read-only access.
While running, the CVS server creates temporary directories. They are named
cvs-servpid
where pid is the process identification number of the server. They are located in the directory specified by the `TMPDIR' environment variable (see section All environment variables which affect CVS), the `-T' global option (see section Global options), or failing that `/tmp'.
In most cases the server will remove the temporary directory when it is done, whether it finishes normally or abnormally. However, there are a few cases in which the server does not or cannot remove the temporary directory, for example:
In cases such as this, you will need to manually remove the `cvs-servpid' directories. As long as there is no server running with process identification number pid, it is safe to do so.
Because renaming files and moving them between directories is somewhat inconvenient, the first thing you do when you start a new project should be to think through your file organization. It is not impossible to rename or move files, but it does increase the potential for confusion and CVS does have some quirks particularly in the area of renaming directories. See section Moving and renaming files.
What to do next depends on the situation at hand.
The first step is to create the files inside the repository. This can be done in a couple of different ways.
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 section Tracking third-party 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 $ diff -r dir.orig yoyodyne/dir $ 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 section 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 section The cvswrappers file.
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.
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.
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.
$ cvs checkout CVSROOT/modules $ cd CVSROOT
tc yoyodyne/tc
$ cvs commit -m "Added the tc module." modules
$ cd .. $ cvs release -d CVSROOT
For many uses of CVS, one doesn't need to worry
too much about revision numbers; CVS assigns
numbers such as 1.1, 1.2, and so on, and
that is all one needs to know. However, some people
prefer to have more knowledge and control concerning
how CVS assigns revision numbers.
If one wants to keep track of a set of revisions involving more than one file, such as which revisions went into a particular release, one uses a tag, which is a symbolic revision which can be assigned to a numeric revision in each file.
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 !
+-----+ +-----+ +-----+ +-----+ +-----+
It is also possible to end up with numbers containing more than one period, for example `1.3.2.2'. Such revisions represent revisions on branches (see section Branching and merging); such revision numbers are explained in detail in section Branches and revisions.
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.
By default, CVS will assign numeric revisions by
leaving the first number the same and incrementing the
second number. For example, 1.1, 1.2,
1.3, etc.
When adding a new file, the second number will always
be one and the first number will equal the highest
first number of any file in that directory. For
example, the current directory contains files whose
highest numbered revisions are 1.7, 3.1,
and 4.12, then an added file will be given the
numeric revision 4.1.
Normally there is no reason to care
about the revision numbers--it is easier to treat them
as internal numbers that CVS maintains, and tags
provide a better way to distinguish between things like
release 1 versus release 2 of your product
(see section Tags--Symbolic revisions). However, if you want to set the
numeric revisions, the `-r' option to cvs
commit can do that. The `-r' option implies the
`-f' option, in the sense that it causes the
files to be committed even if they are not modified.
For example, to bring all your files up to revision 3.0 (including those that haven't changed), you might invoke:
$ cvs commit -r 3.0
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'. If you want to maintain several releases in parallel, you need to use a branch (see section Branching and merging).
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 must
start with an uppercase or lowercase letter and 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 be specially named, for example by
starting with `.', rather than being named analogously to
BASE and HEAD, to avoid conflicts with
actual tag names.
You'll want to choose some convention for naming tags,
based on information such as the name of the program
and the version number of the release. For example,
one might take the name of the program, immediately
followed by the version number with `.' changed to
`-', so that CVS 1.9 would be tagged with the name
cvs1-9. If you choose a consistent convention,
then you won't constantly be guessing whether a tag is
cvs-1-9 or cvs1_9 or what. You might
even want to consider enforcing your convention in the
taginfo file (see section User-defined logging).
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 rel-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 /u/cvsroot/yoyodyne/tc/backend.c,v
Sticky Tag: (none)
Sticky Date: (none)
Sticky Options: (none)
Existing Tags:
rel-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 rel-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 section 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 rel-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 section 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
Sometimes a working copy's revision has extra data associated with it, for example it might be on a branch (see section Branching and merging), or restricted to versions prior to a certain date by `checkout -D' or `update -D'. Because this data persists -- that is, it applies to subsequent commands in the working copy -- we refer to it as sticky.
Most of the time, stickiness is an obscure aspect of CVS that you don't need to think about. However, even if you don't want to use the feature, you may need to know something about sticky tags (for example, how to avoid them!).
You can use the status command to see if any
sticky tags or dates are set:
$ cvs status 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 /u/cvsroot/yoyodyne/tc/driver.c,v
Sticky Tag: rel-1-0-patches (branch: 1.7.2)
Sticky Date: (none)
Sticky Options: (none)
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.
The most common use of sticky tags is to identify which
branch one is working on, as described in
section Accessing branches. However, non-branch
sticky tags have uses as well. 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
commands 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 $
CVS allows you to isolate changes onto a separate line of development, known as a branch. When you change files on a branch, those changes do not appear on the main trunk or other branches.
Later you can move changes from one branch to another
branch (or the main trunk) by merging. Merging
involves first running cvs update -j, to merge
the changes into the working directory.
You can then commit that revision, and thus effectively
copy the changes onto another branch.
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 section Tags--Symbolic revisions) 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 elect to either incorporate them on the main trunk, or leave them on the branch.
You can create a branch with tag -b; for
example, assuming you're in a working copy:
$ cvs tag -b rel-1-0-patches
This splits off a branch based on the current revisions in the working copy, assigning that branch the name `rel-1-0-patches'.
It is important to understand that branches get created in the repository, not in the working copy. Creating a branch based on current revisions, as the above example does, will not automatically switch the working copy to be on the new branch. For information on how to do that, see section Accessing branches.
You can also create a branch without reference to any
working copy, by using rtag:
$ cvs rtag -b -r rel-1-0 rel-1-0-patches tc
`-r rel-1-0' says that this branch should be rooted at the revision that corresponds to the tag `rel-1-0'. It need not be the most recent revision -- it's often useful to split a branch off an old revision (for example, when fixing a bug in a past release otherwise known to be stable).
As with `tag', the `-b' flag tells
rtag to create a branch (rather than just a
symbolic revision name). Note that the numeric
revision number that matches `rel-1-0' will
probably be different from file to file.
So, the full effect of the command is to create a new branch -- named `rel-1-0-patches' -- in module `tc', rooted in the revision tree at the point tagged by `rel-1-0'.
You can retrieve a branch in one of two ways: by checking it out fresh from the repository, or by switching an existing working copy over to the branch.
To check out a branch from the repository, invoke `checkout' with the `-r' flag, followed by the tag name of the branch (see section Creating a branch):
$ cvs checkout -r rel-1-0-patches tc
Or, if you already have a working copy, you can switch it to a given branch with `update -r':
$ cvs update -r rel-1-0-patches tc
or equivalently:
$ cd tc $ cvs update -r rel-1-0-patches
It does not matter if the working copy was originally on the main trunk or on some other branch -- the above command will switch it to the named branch. And similarly to a regular `update' command, `update -r' merges any changes you have made, notifying you of conflicts where they occur.
Once you have a working copy tied to a particular branch, it remains there until you tell it otherwise. This means that changes checked in from the working copy will add new revisions on that branch, while leaving the main trunk and other branches unaffected.
To find out what branch a working copy is on, you can use the `status' command. In its output, look for the field named `Sticky tag' (see section Sticky tags) -- that's CVS's way of telling you the branch, if any, of the current working files:
$ 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 /u/cvsroot/yoyodyne/tc/driver.c,v
Sticky Tag: rel-1-0-patches (branch: 1.7.2)
Sticky Date: (none)
Sticky Options: (none)
Existing Tags:
rel-1-0-patches (branch: 1.7.2)
rel-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 /u/cvsroot/yoyodyne/tc/backend.c,v
Sticky Tag: rel-1-0-patches (branch: 1.4.2)
Sticky Date: (none)
Sticky Options: (none)
Existing Tags:
rel-1-0-patches (branch: 1.4.2)
rel-1-0 (revision: 1.4)
rel-0-4 (revision: 1.4)
Don't be confused by the fact that the branch numbers for each file are different (`1.7.2' and `1.4.2' respectively). The branch tag is the same, `rel-1-0-patches', and the files are indeed on the same branch. The numbers simply reflect the point in each file's revision history at which the branch was made. In the above example, one can deduce that `driver.c' had been through more changes than `backend.c' before this branch was created.
See section Branches and revisions for details about how branch numbers are constructed.
Ordinarily, a file's revision history is a linear series of increments (see section Revision numbers):
+-----+ +-----+ +-----+ +-----+ +-----+
! 1.1 !----! 1.2 !----! 1.3 !----! 1.4 !----! 1.5 !
+-----+ +-----+ +-----+ +-----+ +-----+
However, 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 ! / +---------+ +---------+ +---------+ / / +-----+ +-----+ +-----+ +-----+ +-----+ ! 1.1 !----! 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 section Magic branch numbers). The branch 1.1.1 has a special meaning. See section Tracking third-party sources.
This section describes a CVS feature called magic branches. For most purposes, you need not worry about magic branches; CVS handles them for you. However, they are visible to you in certain circumstances, so it may be useful to have some idea of how it works.
Externally, branch numbers consist of an odd number of dot-separated decimal integers. See section Revision numbers. That is not the whole truth, however. For efficiency reasons CVS sometimes inserts an extra 0 in the second rightmost position (1.2.4 becomes 1.2.0.4, 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 a few places the hiding is incomplete:
cvs log.
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).
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).
+-----+ +-----+ +-----+ +-----+ ! 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 section 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"
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
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.
If the changes which you are merging involve removing
or adding some files, update -j will reflect
such additions or removals.
For example:
cvs update -A touch a b c cvs add a b c ; cvs ci -m "added" a b c cvs tag -b branchtag cvs update -r branchtag touch d ; cvs add d rm a ; cvs rm a cvs ci -m "added d, removed a" cvs update -A cvs update -jbranchtag
After these commands are executed and a `cvs commit' is done, file `a' will be removed and file `d' added in the main branch.
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/testpgm.t testing/test2.t
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. Conversely, the `-R' option can be used to force recursion if `-l' is specified in `~/.cvsrc' (see section Default options and the ~/.cvsrc file).
$ cvs update -l # Don't update files in subdirectories
In the course of a project, one will often add new files. Likewise with removing or renaming, or with directories. The general concept to keep in mind in all these cases is that instead of making an irreversible change you want CVS to record the fact that a change has taken place, just as with modifying an existing file. The exact mechanisms to do this in CVS vary depending on the situation.
To add a new file to a directory, follow these steps.
You can also use the add command to add a new
directory.
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
-k kflag] [-m message] files ...
Schedule files to be added to the repository.
The files or directories specified with add must
already exist in the current directory. 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 section import--Import sources into CVS, using vendor branches.
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 undo the
effect of the remove, unless a commit
command intervened. See section Removing files, for an
example.
The `-k' option specifies the default way that this file will be checked out; for more information see section Substitution modes.
The `-m' option specifies a description for the
file. This description appears in the history log (if
it is enabled, see section The history file). It will also be
saved in the version history inside the repository when
the file is committed. The log command displays
this description. The description can be changed using
`admin -t'. See section admin--Administration. If you omit the
`-m description' flag, an empty string will
be used. You will not be prompted for a description.
For example, the following commands add the file `backend.c' to the repository:
$ cvs add backend.c $ cvs commit -m "Early version. Not yet compilable." backend.c
When you add a file it is added only on the branch which you are working on (see section Branching and merging). You can later merge the additions to another branch if you want (see section Merging can add or remove files).
Modules change. New files are added, and old files disappear. Still, you want to be able to retrieve an exact copy of old releases.
Here is what you can do to remove a file, but remain able to retrieve old revisions:
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.
rm.
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.
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. For a full list of options, see section Quick reference to CVS commands.
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 .
As a convenience you can remove the file and cvs
remove it in one step, by specifying the `-f'
option. For example, the above example could also be
done like this:
$ cd test $ cvs remove -f *.c 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 execute remove for a file, and then
change your mind before you commit, you can undo the
remove with an 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
When you remove a file it is removed only on the branch which you are working on (see section Branching and merging). You can later merge the removals to another branch if you want (see section Merging can add or remove files).
In concept removing directories is somewhat similar to removing files--you want the directory to not exist in your current working directories, but you also want to be able to retrieve old releases in which the directory existed.
The way that you remove a directory is to remove all
the files in it. You don't remove the directory
itself; there is no way to do that.
Instead you specify the `-P' option to
cvs update, cvs checkout, or cvs
export, which will cause CVS to remove empty
directories from working directories. Probably the
best way to do this is to always specify `-P'; if
you want an empty directory then put a dummy file (for
example `.keepme') in it to prevent `-P' from
removing it.
Note that `-P' is implied by the `-r' or `-D'
options of checkout and export. This way
CVS will be able to correctly create the directory
or not depending on whether the particular version you
are checking out contains any files in that directory.
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 section Moving and renaming directories.).
The examples below assume that the file old is renamed to new.
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.
$ 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 again, usually at 1.1, so if that bothers you, use the `-r rev' option to commit. For more information see section Assigning revisions.
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:
Disadvantages:
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 non-branch tag names $ cvs tag -d tag1 new $ cvs tag -d tag2 new ...
By removing the tags you will be able to check out old revisions of the module.
Advantages:
Disadvantages:
The normal way to rename or move a directory is to rename or move each file within it as described in section The Normal way to Rename. Then check out with the `-P' option, as described in section Removing directories.
If you really want to hack the repository to rename or delete a directory in the repository, you can do it like this:
$ cd $CVSROOT/module $ mv old-dir new-dir
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.
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.
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 section log--Print out log information for files).
You can use the history file (see section The history file) to
log various CVS actions. To retrieve the
information from the history file, use the cvs
history command (see section history--Show status of files and users).
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 section 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 section Telling CVS to notify you); 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 section Reference manual for 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.
Here is an example of using taginfo to log tag and rtag commands. In the taginfo file put:
ALL /usr/local/cvsroot/CVSROOT/loggit
Where `/usr/local/cvsroot/CVSROOT/loggit' contains the following script:
#!/bin/sh echo "$@" >>/home/kingdon/cvsroot/CVSROOT/taglog
-flR] [-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 section diff--Show differences between revisions).
The options to cvs annotate are listed in
section Quick reference to CVS commands, and can be used to select the files
and revisions to annotate. The options are described
in more detail in section Common command options.
The most common use for CVS is to store text files. With text files, CVS can merge revisions, display the differences between revisions in a human-visible fashion, and other such operations. However, if you are willing to give up a few of these abilities, CVS can store binary files. For example, one might store a web site in CVS including both text files and binary images.
While the need to manage binary files may seem obvious if the files that you customarily work with are binary, putting them into version control does present some additional issues.
One basic function of version control is to show the
differences between two revisions. For example, if
someone else checked in a new version of a file, you
may wish to look at what they changed and determine
whether their changes are good. For text files,
CVS provides this functionality via the cvs
diff command. For binary files, it may be possible to
extract the two revisions and then compare them with a
tool external to CVS (for example, word processing
software often has such a feature). If there is no
such tool, one must track changes via other mechanisms,
such as urging people to write good log messages, and
hoping that the changes they actually made were the
changes that they intended to make.
Another ability of a version control system is the ability to merge two revisions. For CVS this happens in two contexts. The first is when users make changes in separate working directories (see section Multiple developers). The second is when one merges explicitly with the `update -j' command (see section Branching and merging).
In the case of text files, CVS can merge changes made independently, and signal a conflict if the changes conflict. With binary files, the best that CVS can do is present the two different copies of the file, and leave it to the user to resolve the conflict. The user may choose one copy or the other, or may run an external merge tool which knows about that particular file format, if one exists. Note that having the user merge relies primarily on the user to not accidentally omit some changes, and thus is potentially error prone.
If this process is thought to be undesirable, the best choice may be to avoid merging. To avoid the merges that result from separate working directories, see the discussion of reserved checkouts (file locking) in section Multiple developers. To avoid the merges resulting from branches, restrict use of branches.
There are two issues with using CVS to store binary files. The first is that CVS by default converts 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 section 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.
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 # For non-unix systems: # Copy in a good copy of the file from outside CVS $ cvs commit -m "make it binary" kotest
When you check in the file `kotest' the file is
not preserved as a binary file, because you did not
check it in as a binary file. 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. If you need to
cope with line endings (that is, you are using
CVS 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.
On unix, the cvs update -A command suffices.
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 section The cvswrappers file.
There is currently no way to have CVS detect
whether a file is binary based on its contents. The
main difficulty with designing such a feature is that
it is not clear how to distinguish between binary and
non-binary files, and the rules to apply would vary
considerably with the operating system.
When more than one person works on a software project
things often get complicated. Often, two people try to
edit the same file simultaneously. One solution, known
as file locking or reserved checkouts, is
to allow only one person to edit each file at a time.
This is the only solution with some version control
systems, including RCS and SCCS. Currently
the usual way to get reserved checkouts with CVS
is the cvs admin -l command (see section admin options). This is not as nicely integrated into
CVS as the watch features, described below, but it
seems that most people with a need for reserved
checkouts find it adequate.
It also may be possible to use the watches
features described below, together with suitable
procedures (not enforced by software), to avoid having
two people edit at the same time.
The default model with CVS is known as unreserved checkouts. In this model, developers can 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.
CVS also supports mechanisms which facilitate various kinds of communcation, without actually enforcing rules like reserved checkouts do.
The rest of this chapter describes how these various models work, and some of the issues involved in choosing between them.
Based on what operations you have performed on a
checked out file, and what operations others have
performed to that file in the repository, one can
classify a file in a number of states. The states, as
reported by the status command, are:
add, and not yet
committed your changes.
remove, and not yet
committed your changes.
update rather than
checkout to get that newer revision.
update command gave a conflict. If you have not
already done so, you need to
resolve the conflict as described in section Conflicts example.
add.
To help clarify the file status, status also
reports the Working revision which is the
revision that the file in the working directory derives
from, and the Repository revision which is the
latest revision in the repository for the branch in
use.
The options to status are listed in
section Quick reference to CVS commands. For information on its Sticky tag
and Sticky date output, see section Sticky tags.
For information on its Sticky options output,
see the `-k' option in section update options.
You can think of the status and update
commands as somewhat complementary. You use
update to bring your files up to date, and you
can use status to give you some idea of what an
update would do (of course, the state of the
repository might change before you actually run
update). In fact, if you want a command to
display file status in a more brief format than is
displayed by the status command, you can invoke
$ cvs -n -q update
The `-n' option means to not actually do the
update, but merely to display statuses; the `-q'
option avoids printing the name of each directory. For
more information on the update command, and
these options, see section Quick reference to CVS commands.
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 section update--Bring work tree in sync with repository, for a complete description of the
update command.
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
For your protection, CVS will refuse to check in a file if a conflict occurred and you have not resolved the conflict. Currently to resolve a conflict, you must change the timestamp on the file. In previous versions of CVS, you also needed to insure that the file contains no conflict markers. Because your file may legitimately contain conflict markers (that is, occurrences of `>>>>>>> ' at the start of a line that don't mark a conflict), the current version of CVS will print a warning and proceed to check in the file.
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.
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 section The modules file. See section 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.
If several developers try to run CVS at the same time, one may get the following message:
[11:43:23] waiting for bach's lock in /usr/local/cvsroot/foo
CVS will try again every 30 seconds, and either continue with the operation or print the message again, if it still needs to wait. If a lock seems to stick around for an undue amount of time, find the person holding the lock and ask them about the cvs command they are running. If they aren't running a cvs command, look in the repository directory mentioned in the message and remove files which they own whose names start with `#cvs.rfl', `#cvs.wfl', or `#cvs.lock'.
Note that these locks are to protect CVS's internal data structures and have no relationship to the word lock in the sense used by RCS---which refers to reserved checkouts (see section Multiple developers).
Any number of people can be reading from a given repository at a time; only when someone is writing do the locks prevent other people from reading or writing.
One might hope for the following property
If someone commits some changes in one cvs command, then an update by someone else will either get all the changes, or none of them.
but CVS does not have this property. For example, given the files
a/one.c a/two.c b/three.c b/four.c
if someone runs
cvs ci a/two.c b/three.c
and someone else runs cvs update at the same
time, the person running update might get only
the change to `b/three.c' and not the change to
`a/two.c'.
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.
To enable the watch features, you first specify that certain files are to be watched.
-lR] files ...
Specify that developers should run cvs edit
before editing files. CVS will create working
copies of files read-only, to remind developers
to run the cvs edit command before working on
them.
If files includes the name of a directory, CVS
arranges to watch all files added to the corresponding
repository directory, and sets a default for files
added in the future; this allows the user to set
notification policies on a per-directory basis. The
contents of the directory are processed recursively,
unless the -l option is given.
The -R option can be used to force recursion if the -l
option is set in `~/.cvsrc' (see section Default options and the ~/.cvsrc file).
If files is omitted, it defaults to the current directory.
-lR] files ...
Do not provide notification about work on files. CVS will create working copies of files read-write.
The files and options are processed as for cvs
watch on.
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.
-a action] [-lR] files ...
Add the current user to the list of people to receive notification of work done on files.
The -a option specifies what kinds of events CVS should notify
the user about. action is one of the following:
edit
cvs edit command (described
below) to a file.
unedit
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
all
none
cvs edit,
described below.)
The -a option may appear more than once, or not at all. If
omitted, the action defaults to all.
The files and options are processed as for the
cvs watch commands.
-a action] [-lR] files ...
Remove a notification request established using cvs watch add;
the arguments are the same. If the -a option is present, only
watches for the specified actions are removed.
When the conditions exist for notification, CVS
calls the `notify' administrative file. Edit
`notify' as one edits the other administrative
files (see section The administrative files). This
file follows the usual conventions for administrative
files (see section The common syntax), where each line is a regular
expression followed by a command to execute. The
command should contain a single ocurrence of `%s'
which will be replaced by the user to notify; the rest
of the information regarding the notification will be
supplied to the command on standard input. The
standard thing to put in the notify file is the
single line:
ALL mail %s -s \"CVS notification\"
This causes users to be notified by electronic mail.
Note that if you set this up in the straightforward way, users receive notifications on the server machine. One could of course write a `notify' script which directed notifications elsewhere, but to make this easy, CVS allows you to associate a notification address for each user. To do so create a file `users' in `CVSROOT' with a line for each user in the format user:value. Then instead of passing the name of the user to be notified to `notify', CVS will pass the value (normally an email address on some other machine).
CVS does not notify you for your own changes. Currently this check is done based on whether the user name of the person taking the action which triggers notification matches the user name of the person getting notification. In fact, in general, the watches features only track one edit by each user. It probably would be more useful if watches tracked each working directory separately, so this behavior might be worth changing.
Since a file which is being watched is checked out
read-only, you cannot simply edit it. To make it
read-write, and inform others that you are planning to
edit it, use the cvs edit command. Some systems
call this a checkout, but CVS uses that term
for obtaining a copy of the sources (see section Getting the source), an operation which those systems call a
get or a fetch.
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 options are processed as for the cvs
watch commands.
Caution: If the PreservePermissions
option is enabled in the repository (see section The CVSROOT/config configuration file),
CVS will not change the permissions on any of the
files. The reason for this change is to ensure
that using `cvs edit' does not interfere with the
ability to store file permissions in the CVS
repository.
Normally when you are done with a set of changes, you
use the cvs commit command, which checks in your
changes and returns the watched files to their usual
read-only state. But if you instead decide to abandon
your changes, or not to make any changes, you can use
the cvs unedit command.
-lR] files ...
Abandon work on the working files files, and revert them to the
repository versions on which they are based. CVS makes those
files read-only for which users have requested notification using
cvs watch on. CVS notifies users who have requested unedit
notification for any of files.
The files and options are processed as for the
cvs watch commands.
If watches are not in use, the unedit command
probably does not work, and the way to revert to the
repository version is to remove the file and then use
cvs update to get a new copy. The meaning is
not precisely the same; removing and updating may also
bring in some changes which have been made in the
repository since the last time you updated.
When using client/server CVS, you can use the
cvs edit and cvs unedit commands even if
CVS is unable to succesfully communicate with the
server; the notifications will be sent upon the next
successful CVS command.
-lR] files ...
List the users currently watching changes to files. The report includes the files being watched, and the mail address of each watcher.
The files and options are processed as for the
cvs watch commands.
-lR] files ...
List the users currently working on files. The report includes the mail address of each user, the time when the user began working with the file, and the host and path of the working directory containing the file.
The files and options are processed as for the
cvs watch commands.
If you use the watch features on a repository, it creates `CVS' directories in the repository and stores the information about watches in that directory. If you attempt to use CVS 1.6 or earlier with the repository, you get an error message such as the following (all on one line):
cvs update: cannot open CVS/Entries for reading: No such file or directory
and your operation will likely be aborted. To use the
watch features, you must upgrade all copies of CVS
which use that repository in local or server mode. If
you cannot upgrade, use the watch off and
watch remove commands to remove all watches, and
that will restore the repository to a state which
CVS 1.6 can cope with.
Reserved and unreserved checkouts each have pros and cons. Let it be said that a lot of this is a matter of opinion or what works given different groups' working styles, but here is a brief description of some of the issues. There are many ways to organize a team of developers. CVS does not try to enforce a certain organization. It is a tool that can be used in several ways.
Reserved checkouts can be very counter-productive. If two persons want to edit different parts of a file, there may be no reason to prevent either of them from doing so. Also, it is common for someone to take out a lock on a file, because they are planning to edit it, but then forget to release the lock.
People, especially people who are familiar with reserved checkouts, often wonder how often conflicts occur if unreserved checkouts are used, and how difficult they are to resolve. The experience with many groups is that they occur rarely and usually are relatively straightforward to resolve.
The rarity of serious conflicts may be surprising, until one realizes that they occur only when two developers disagree on the proper design for a given section of code; such a disagreement suggests that the team has not been communicating properly in the first place. In order to collaborate under any source management regimen, developers must agree on the general design of the system; given this agreement, overlapping changes are usually straightforward to merge.
In some cases unreserved checkouts are clearly inappropriate. If no merge tool exists for the kind of file you are managing (for example word processor files or files edited by Computer Aided Design programs), and it is not desirable to change to a program which uses a mergeable data format, then resolving conflicts is going to be unpleasant enough that you generally will be better off to simply avoid the conflicts instead, by using reserved checkouts.
The watches features described above in section Mechanisms to track who is editing files can be considered to be an intermediate model between reserved checkouts and unreserved checkouts. When you go to edit a file, it is possible to find out who else is editing it. And rather than having the system simply forbid both people editing the file, it can tell you what the situation is and let you figure out whether it is a problem in that particular case or not. Therefore, for some groups it can be considered the best of both the reserved checkout and unreserved checkout worlds.
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.
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 section 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.
As long as you edit source files inside your working copy of a module you can always find out the state of your files via `cvs status' and `cvs log'. But as soon as you export the files from your development environment it becomes harder to identify which revisions they are.
CVS can use a mechanism known as keyword
substitution (or keyword expansion) to help
identifying the files. Embedded strings of the form
$keyword$ and
$keyword:...$ in a file are replaced
with strings of the form
$keyword:value$ whenever you obtain
a new revision of the file.
This is a list of the keywords:
$Author$
$Date$
$Header$
$Id$
$Header$, except that the RCS
filename is without a path.
$Name$
$Locker$
$Log$
$Log:...$.
Each new line is prefixed with the same string which
precedes the $Log keyword. For example, if the
file contains
/* Here is what people have been up to: * * $Log: frob.c,v $ * Revision 1.1 1997/01/03 14:23:51 joe * Add the superfrobnicate option * */then additional lines which are added when expanding the
$Log keyword will be preceded by ` * '.
Unlike previous versions of CVS and RCS, the
comment leader from the RCS file is not used.
The $Log keyword is useful for
accumulating a complete change log in a source file,
but for several reasons it can be problematic.
See section Problems with the $Log$ keyword.
$RCSfile$
$Revision$
$Source$
$State$
cvs admin -s---see section admin options.
To include a keyword string you simply include the
relevant text string, such as $Id$, inside the
file, and commit the file. CVS will automatically
expand the string as part of the commit operation.
It is common to embed the $Id$ string in
the source files so that it gets passed through to
generated files. For example, if you are managing
computer program source code, you might include a
variable which is initialized to contain that string.
Or some C compilers may provide a #pragma ident
directive. Or a document management system might
provide a way to pass a string through to generated
files.
The ident command (which is part of the RCS
package) can be used to extract keywords and their
values from a file. This can be handy for text files,
but it is even more useful for extracting keywords from
binary files.
$ ident samp.c
samp.c:
$Id: samp.c,v 1.5 1993/10/19 14:57:32 ceder Exp $
$ gcc samp.c
$ ident a.out
a.out:
$Id: samp.c,v 1.5 1993/10/19 14:57:32 ceder Exp $
SCCS is another popular revision control system.
It has a command, what, which is very similar to
ident and used for the same purpose. Many sites
without RCS have SCCS. Since what
looks for the character sequence @(#) it is
easy to include keywords that are detected by either
command. Simply prefix the RCS keyword with the
magic SCCS phrase, like this:
static char *id="@(#) $Id: ab.c,v 1.5 1993/10/19 14:57:32 ceder Exp $";
Keyword substitution has its disadvantages. Sometimes you might want the literal text string $Author$ to appear inside a file without CVS interpreting it as a keyword and expanding it into something like $Author: ceder $.
There is unfortunately no way to selectively turn off keyword substitution. You can use `-ko' (see section Substitution modes) to turn off keyword substitution entirely.
In many cases you can avoid using keywords in
the source, even though they appear in the final
product. For example, the source for this manual
contains `$@asis{}Author$' whenever the text
$Author$ should appear. In nroff
and troff you can embed the null-character
\& inside the keyword for a similar effect.
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 section Handling binary files.
The modes available are:
$Revision: 5.7 $ for the Revision
keyword.
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.
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.
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 section export--Export sources from CVS, similar to checkout. But be aware that doesn't
handle an export containing binary files correctly.
$Log$ keyword
The $Log$ keyword is somewhat
controversial. As long as you are working on your
development system the information is easily accessible
even if you do not use the $Log$
keyword--just do a cvs log. Once you export
the file the history information might be useless
anyhow.
A more serious concern is that CVS is not good at
handling $Log$ entries when a branch is
merged onto the main trunk. Conflicts often result
from the merging operation.
People also tend to "fix" the log entries in the file
(correcting spelling mistakes and maybe even factual
errors). If that is done the information from
cvs log will not be consistent with the
information inside the file. This may or may not be a
problem in real life.
It has been suggested that the $Log$
keyword should be inserted last in the file, and
not in the files header, if it is to be used at all.
That way the long list of change messages will not
interfere with everyday source file browsing.
If you modify a program to better fit your site, you probably want to include your modifications when the next release of the program arrives. CVS can help you with this task.
In the terminology used in CVS, the supplier of the program is called a vendor. The unmodified distribution from the vendor is checked in on its own branch, the vendor branch. CVS reserves branch 1.1.1 for this use.
When you modify the source and commit it, your revision will end up on the main trunk. When a new release is made by the vendor, you commit it on the vendor branch and copy the modifications onto the main trunk.
Use the import command to create and update
the vendor branch. When you import a new file,
the vendor branch is made the `head' revision, so
anyone that checks out a copy of the file gets that
revision. When a local modification is committed it is
placed on the main trunk, and made the `head'
revision.
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 section Multiple vendor branches.). The
release tags are symbolic names for a particular
release, such as `FSF_0_04'.
Note that import does not change the
directory in which you invoke it. In particular, it
does not set up that directory as a CVS working
directory; if you want to work with the sources import
them first and then check them out into a different
directory (see section Getting the source).
Suppose you have the sources to a program called
wdiff in a directory `wdiff-0.04',
and are going to make private modifications that you
want to be able to use even when new releases are made
in the future. You start by importing the source to
your repository:
$ cd wdiff-0.04 $ cvs import -m "Import of FSF v. 0.04" fsf/wdiff FSF_DIST WDIFF_0_04
The vendor tag is named `FSF_DIST' in the above example, and the only release tag assigned is `WDIFF_0_04'.
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 section 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.
You can also revert local changes completely and return to the latest vendor release by changing the `head' revision back to the vendor branch on all files. For example, if you have a checked-out copy of the sources in `~/work.d/wdiff', and you want to revert to the vendor's version for all the files in that directory, you would type:
$ cd ~/work.d/wdiff $ cvs admin -bWDIFF .
You must specify the `-bWDIFF' without any space after the `-b'. See section admin options.
Use the `-k' wrapper option to tell import which files are binary. See section The cvswrappers file.
The sources which you are importing may contain keywords (see section Keyword substitution). For example, the vendor may use CVS or some other system which uses similar keyword expansion syntax. If you just import the files in the default fashion, then the keyword expansions supplied by the vendor will be replaced by keyword expansions supplied by your own copy of CVS. It may be more convenient to maintain the expansions supplied by the vendor, so that this information can supply information about the sources that you imported from the vendor.
To maintain the keyword expansions supplied by the
vendor, supply the `-ko' option to cvs
import the first time you import the file.
This will turn off keyword expansion
for that file entirely, so if you want to be more
selective you'll have to think about what you want
and use the `-k' option to cvs update or
cvs admin as appropriate.
All the examples so far assume that there is only one vendor from which you are getting sources. In some situations you might get sources from a variety of places. For example, suppose that you are dealing with a project where many different people and teams are modifying the software. There are a variety of ways to handle this, but in some cases you have a bunch of source trees lying around and what you want to do more than anything else is just to all put them in CVS so that you at least have them in one place.
For handling situations in which there may be more than
one vendor, you may specify the `-b' option to
cvs import. It takes as an argument the vendor
branch to import to. The default is `-b 1.1.1'.
For example, suppose that there are two teams, the red team and the blue team, that are sending you sources. You want to import the red team's efforts to branch 1.1.1 and use the vendor tag RED. You want to import the blue team's efforts to branch 1.1.3 and use the vendor tag BLUE. So the commands you might use are:
$ cvs import dir RED RED_1-0 $ cvs import -b 1.1.3 dir BLUE BLUE_1-5
Note that if your vendor tag does not match your `-b' option, CVS will not detect this case! For example,
$ cvs import -b 1.1.3 dir RED RED_1-0
Be careful; this kind of mismatch is sure to sow confusion or worse. I can't think of a useful purpose for the ability to specify a mismatch here, but if you discover such a use, don't. CVS is likely to make this an error in some future release.
As mentioned in the introduction, CVS does not contain software for building your software from source code. This section describes how various aspects of your build system might interact with CVS.
One common question, especially from people who are
accustomed to RCS, is how to make their build get
an up to date copy of the sources. The answer to this
with CVS is two-fold. First of all, since
CVS itself can recurse through directories, there
is no need to modify your `Makefile' (or whatever
configuration file your build tool uses) to make sure
each file is up to date. Instead, just use two
commands, first cvs -q update and then
make or whatever the command is to invoke your
build tool. Secondly, you do not necessarily
want to get a copy of a change someone else made
until you have finished your own work. One suggested
approach is to first update your sources, then
implement, build and
test the change you were thinking of, and then commit
your sources (updating first if necessary). By
periodically (in between changes, using the approach
just described) updating your entire tree, you ensure
that your sources are sufficiently up to date.
One common need is to record which versions of which
source files went into a particular build. This kind
of functionality is sometimes called bill of
materials or something similar. The best way to do
this with CVS is to use the tag command to
record which versions went into a given build
(see section Tags--Symbolic revisions).
Using CVS in the most straightforward manner possible, each developer will have a copy of the entire source tree which is used in a particular build. If the source tree is small, or if developers are geographically dispersed, this is the preferred solution. In fact one approach for larger projects is to break a project down into smaller separately-compiled subsystems, and arrange a way of releasing them internally so that each developer need check out only those subsystems which are they are actively working on.
Another approach is to set up a structure which allows
developers to have their own copies of some files, and
for other files to access source files from a central
location. Many people have come up with some such a
system using features such as the symbolic link feature
found in many operating systems, or the VPATH
feature found in many versions of make. One build
tool which is designed to help with this kind of thing
is Odin (see
ftp://ftp.cs.colorado.edu/pub/distribs/odin).
In normal circumstances, CVS works only with regular files. Every file in a project is assumed to be persistent; it must be possible to open, read and close them; and so on. CVS also ignores file permissions and ownerships, leaving such issues to be resolved by the developer at installation time. In other words, it is not possible to "check in" a device into a repository; if the device file cannot be opened, CVS will refuse to handle it. Files also lose their ownerships and permissions during repository transactions.
If the configuration variable PreservePermissions
(see section The CVSROOT/config configuration file) is set in the repository, CVS will
save the following file characteristics in the
repository:
Using the PreservePermissions option affects the
behavior of CVS in several ways. First, some of the
new operations supported by CVS are not accessible to
all users. In particular, file ownership and special
file characteristics may only be changed by the
superuser. When the PreservePermissions
configuration variable is set, therefore, users will
have to be `root' in order to perform CVS operations.
When PreservePermissions is in use, some CVS
operations (such as `cvs status') will not
recognize a file's hard link structure, and so will
emit spurious warnings about mismatching hard links.
The reason is that CVS's internal structure does not
make it easy for these operations to collect all the
necessary data about hard links, so they check for file
conflicts with inaccurate data.
A more subtle difference is that CVS considers a file to have changed only if its contents have changed (specifically, if the modification time of the working file does not match that of the repository's file). Therefore, if only the permissions, ownership or hard linkage have changed, or if a device's major or minor numbers have changed, CVS will not notice. In order to commit such a change to the repository, you must force the commit with `cvs commit -f'. This also means that if a file's permissions have changed and the repository file is newer than the working copy, performing `cvs update' will silently change the permissions on the working copy.
Changing hard links in a CVS repository is particularly
delicate. Suppose that file `foo' is linked to
file `old', but is later relinked to file
`new'. You can wind up in the unusual situation
where, although `foo', `old' and `new'
have all had their underlying link patterns changed,
only `foo' and `new' have been modified, so
`old' is not considered a candidate for checking
in. It can be very easy to produce inconsistent
results this way. Therefore, we recommend that when it
is important to save hard links in a repository, the
prudent course of action is to touch any file
whose linkage or status has changed since the last
checkin. Indeed, it may be wise to touch *
before each commit in a directory with complex hard
link structures.
It is worth noting that only regular files may be merged, for reasons that hopefully are obvious. If `cvs update' or `cvs checkout -j' attempts to merge a symbolic link with a regular file, or two device files for different kinds of devices, CVS will report a conflict and refuse to perform the merge. At the same time, `cvs diff' will not report any differences between these files, since no meaningful textual comparisons can be made on files which contain no text.
The PreservePermissions features do not work
with client/server CVS. Another limitation is
that hard links must be to other files within the same
directory; hard links across directories are not
supported.
This appendix describes the overall structure of CVS commands, and describes some commands in detail (others are described elsewhere; for a quick reference to CVS commands, see section Quick reference to CVS commands).
The overall format of all CVS commands is:
cvs [ cvs_options ] cvs_command [ command_options ] [ command_args ]
cvs
cvs_options
cvs_command
command_options
command_args
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.
CVS can indicate to the calling environment whether it succeeded or failed by setting its exit status. The exact way of testing the exit status will vary from one operating system to another. For example in a unix shell script the `$?' variable will be 0 if the last command returned a successful exit status, or greater than 0 if the exit status indicated failure.
If CVS is successful, it returns a successful status;
if there is an error, it prints an error message and
returns a failure status. The one exception to this is
the cvs diff command. It will return a
successful status if it found no differences, or a
failure status if there were differences or if there
was an error. Because this behavior provides no good
way to detect errors, in the future it is possible that
cvs diff will be changed to behave like the
other CVS commands.
There are some command_options that are used so
often that you might have set up an alias or some other
means to make sure you always specify that option. One
example (the one that drove the implementation of the
`.cvsrc' support, actually) is that many people find the
default output of the `diff' command to be very
hard to read, and that either context diffs or unidiffs
are much easier to understand.
The `~/.cvsrc' file is a way that you can add
default options to cvs_commands within cvs,
instead of relying on aliases or other shell scripts.
The format of the `~/.cvsrc' file is simple. The
file is searched for a line that begins with the same
name as the cvs_command being executed. If a
match is found, then the remainder of the line is split
up (at whitespace characters) into separate options and
added to the command arguments before any
options from the command line.
If a command has two names (e.g., checkout and
co), the official name, not necessarily the one
used on the command line, will be used to match against
the file. So if this is the contents of the user's
`~/.cvsrc' file:
log -N diff -u update -P checkout -P
the command `cvs checkout foo' would have the `-P' option added to the arguments, as well as `cvs co foo'.
With the example file above, the output from `cvs
diff foobar' will be in unidiff format. `cvs diff
-c foobar' will provide context diffs, as usual.
Getting "old" format diffs would be slightly more
complicated, because diff doesn't have an option
to specify use of the "old" format, so you would need
`cvs -f diff foobar'.
In place of the command name you can use cvs to
specify global options (see section Global options). For
example the following line in `.cvsrc'
cvs -z6
causes CVS to use compression level 6.
The available `cvs_options' (that are given to the left of `cvs_command') are:
--allow-root=rootdir
-a
-b bindir
-T tempdir
$TMPDIR environment
variable and any precompiled directory. This parameter should be
specified as an absolute pathname.
-d cvs_root_directory
$CVSROOT environment variable. See section The Repository.
-e editor
$CVSEDITOR and $EDITOR
environment variables. For more information, see
section Committing your changes.
-f
-H
--help
-l
-n
-Q
-q
-r
$CVSREAD environment variable is set
(see section All environment variables which affect CVS). The default is to
make working files writable, unless watches are on
(see section Mechanisms to track who is editing files).
-s variable=value
-t
-v
--version
-w
$CVSREAD environment variable.
Files are created read-write by default, unless $CVSREAD is
set or `-r' is given.
-x
-z gzip-level
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
checkout,
diff, export, history,
rdiff, rtag, and update commands.
(The history command uses this option in a
slightly different way; see section history options).
A wide variety of date formats are supported by
CVS. The most standard ones are ISO8601 (from the
International Standards Organization) and the Internet
e-mail standard (specified in RFC822 as amended by
RFC1123).
ISO8601 dates have many variants but a few examples
are:
1972-09-24 1972-09-24 20:05For more details about ISO8601 dates, see:
http://www.ft.uni-erlangen.de/~mskuhn/iso-time.htmlIn addition to the dates allowed in Internet e-mail itself, CVS also allows some of the fields to be omitted. For example:
24 Sep 1972 20:05 24 SepThe date is interpreted as being in the local timezone, unless a specific timezone is specified. These two date formats are preferred. However, CVS currently accepts a wide variety of other date formats. They are intentionally not documented here in any detail, and future versions of CVS might not accept all of them. One such format is
month/day/year. This may
confuse people who are accustomed to having the month
and day in the other order; `1/4/96' is January 4,
not April 1.
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
annotate, checkout, export,
rdiff, rtag, and update.
Warning: The commit and remove
commands also have a
`-f' option, but it has a different behavior for
those commands. See section commit options, and
section Removing files.
-k kflag
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, import and
update commands.
-l
annotate, checkout,
commit, diff, edit, editors, export,
log, rdiff, remove, rtag,
status, tag, unedit, update, watch,
and watchers.
-m message
add,
commit and import.
-n
checkout, commit, export,
and rtag commands.
-P
-p
checkout and update commands.
-R
annotate, checkout,
commit, diff, edit, editors, export,
rdiff, remove, rtag,
status, tag, unedit, update, watch,
and watchers.
-r tag
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
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 section Sticky tags). The
tag can be either a symbolic or numeric tag.
See section Tags--Symbolic revisions.
Specifying the `-q' global option along with the
`-r' command option is often useful, to suppress
the warning messages when the RCS 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.
-W
import,
and update.
This is the CVS interface to assorted administrative facilities. Some of them have questionable usefulness for CVS but exist for historical purposes. Some of the questionable options are likely to disappear in the future. This command does work recursively, so extreme care should be used.
On unix, if there is a group named cvsadmin,
only members of that group can run cvs admin.
This group should exist on the server, or any system
running the non-client/server CVS. To disallow
cvs admin for all users, create a group with no
users in it. On NT, the cvsadmin feature does
not exist and all users can run cvs admin.
Some of these options have questionable usefulness for CVS but exist for historical purposes. Some even make it impossible to use CVS until you undo the effect!
-Aoldfile
-alogins
-b[rev]
cvs admin -b: to revert to the vendor's
version when using vendor branches (see section Reverting to the latest vendor release).
There can be no space between `-b' and its argument.
-cstring
-e[logins]
-I
-i
cvs add command
(see section Adding files to a directory).
-ksubst
cvs update, cvs export, or cvs
checkout overrides this default.
-l[rev]
-L
-mrev:msg
-Nname[:[rev]]
-nname[:[rev]]
-orange
rev1::rev2
::rev
rev::
rev
rev1:rev2
:rev
rev:
cvs tag -d, then run
cvs admin -o. If one specifies the
non-`::' syntaxes, then CVS will delete the
revisions but leave the symbolic names pointing to
nonexistent revisions. This behavior is preserved for
compatibility with previous versions of CVS, but
because it isn't very useful, in the future it may
change to be like the `::' case.
Due to the way CVS handles branches rev
cannot be specified symbolically if it is a branch.
See section 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 section Merging differences between any two revisions).
-q
-sstate[:rev]
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]
-t-string
-U
-u[rev]
. by itself.
There can be no space between `-u' and its argument.
-Vn
-xsuffixes
Create or update 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 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 section The modules file.
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 section Global options) is specified, the
CVSREAD environment variable is specified
(see section All environment variables which affect CVS), or a watch is in
effect for that file (see section Mechanisms to track who is editing files).
Note that running checkout on a directory that was already
built by a prior checkout is also permitted.
This is similar to specifying the `-d' option
to the update command in the sense that new
directories that have been created in the repository
will appear in your work area.
However, checkout takes a module name whereas
update takes a directory name. Also
to use checkout this way it must be run from the
top level directory (where you originally ran
checkout from), so before you run
checkout to update an existing directory, don't
forget to change your directory to the top level
directory.
For the output produced by the checkout command
see section update output.
These standard options are supported by checkout
(see section Common command options, for a complete description of
them):
-D date
-f
-k kflag
status command can be viewed
to see the sticky options. See section Quick reference to CVS commands, for
more information on the status command.
-l
-n
-P
-p
-R
-r tag
In addition to those, you can use these special command
options with checkout:
-A
-c
-d dir
-j tag
-N
-s
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
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 section update--Bring work tree in sync with repository).
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 section The modules file, and see section Loginfo)
and placed in the RCS file inside the
repository. This log message can be retrieved with the
log command; see section log--Print out log information for files. 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.
These standard options are supported by commit
(see section Common command options, for a complete description of
them):
-l
-n
-R
-r revision
commit also supports these options:
-F file
-f
$ cvs commit -f file $ cvs commit -r 1.8 fileThe `-f' option disables recursion (i.e., it implies `-l'). To force CVS to commit a new revision for all files in all subdirectories, you must use `-f -R'.
-m message
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 section tag--Add a symbolic tag to checked out versions of files
or see section rtag--Add a symbolic tag to a module). 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.
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
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 for diff is different than for other CVS commands; for details section CVS's exit status.
These standard options are supported by diff
(see section Common command options, for a complete description of
them):
-D date
-k kflag
-l
-R
-r tag
The following options specify the format of the output. They have the same meaning as in GNU diff.
-0 -1 -2 -3 -4 -5 -6 -7 -8 -9 --binary --brief --changed-group-format=arg -c -C nlines --context[=lines] -e --ed -t --expand-tabs -f --forward-ed --horizon-lines=arg --ifdef=arg -w --ignore-all-space -B --ignore-blank-lines -i --ignore-case -I regexp --ignore-matching-lines=regexp -h -b --ignore-space-change -T --initial-tab -L label --label=label --left-column -d --minimal -N --new-file --new-line-format=arg --old-line-format=arg --paginate -n --rcs -s --report-identical-files -p --show-c-function -y --side-by-side -F regexp --show-function-line=regexp -H --speed-large-files --suppress-common-lines -a --text --unchanged-group-format=arg -u -U nlines --unified[=lines] -V arg -W columns --width=columns
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
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 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 keyword strings. If
you want to be able to use ident you must not
use `-kv'.
These standard options are supported by export
(see section Common command options, for a complete description of
them):
-D date
-f
-l
-n
-R
-r tag
In addition, these options (that are common to
checkout and export) are also supported:
-d dir
-k subst
-N
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 `$CVSROOT/CVSROOT/history'.
Warning: history uses `-f', `-l',
`-n', and `-p' in ways that conflict with the
normal use inside CVS (see section Common command options).
Several options (shown above as `-report') control what kind of report is generated:
-c
-e
-m module
-o
-T
-x type
F
O
E
T
C
G
U
W
A
M
R
The options shown as `-flags' constrain or expand the report without requiring option arguments:
-a
history).
-l
-w
history is
executing.
The options shown as `-options args' constrain the report based on an argument:
-b str
-D date
-p repository
-r rev
-t tag
-u name
Use import to incorporate an entire source
distribution from an outside source (e.g., a source
vendor) into your source repository directory. You can
use this command both for initial creation of a
repository, and for wholesale updates to the module
from the outside source. See section Tracking third-party sources, for
a discussion on this subject.
The repository argument gives a directory name (or a path to a directory) under the CVS root directory for repositories; if the directory did not exist, import creates it.
When you use import for updates to source that has been modified in your source repository (since a prior import), it will notify you of any files that conflict in the two branches of development; use `checkout -j' to reconcile the differences, as import instructs you to do.
If CVS decides a file should be ignored (see section Ignoring files via cvsignore), it does not import it and prints `I ' followed by the filename (see section import output, for a complete description of the output).
If the file `$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 section The cvswrappers file.
The outside source is saved in a first-level 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.
Note that import does not change the
directory in which you invoke it. In particular, it
does not set up that directory as a CVS working
directory; if you want to work with the sources import
them first and then check them out into a different
directory (see section Getting the source).
This standard option is supported by import
(see section Common command options, for a complete description):
-m message
There are the following additional special options.
-b branch
-k subst
-I name
-W spec
import 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
N file
C file
I file
L file
cvs import ignores symbolic links.
People periodically suggest that this behavior should
be changed, but if there is a consensus on what it
should be changed to, it doesn't seem to be apparent.
(Various options in the `modules' file can be used
to recreate symbolic links on checkout, update, etc.;
see section The modules file.)
See section Tracking third-party sources, and section Creating a directory tree from a number of files.
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).
Warning: log uses `-R' in a way that conflicts
with the normal use inside CVS (see section Common command options).
By default, log prints all information that is
available. All other options restrict the output.
-b
-d dates
d1<d2
d2>d1
<d
d>
d<
>d
d
-h
-l
-N
-R
-rrevisions
rev1:rev2
:rev
rev:
branch
branch1:branch2
branch.
-s states
-t
-wlogins
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'.
Contributed examples are gratefully accepted.
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.
These standard options are supported by rdiff
(see section Common command options, for a complete description of
them):
-D date
-f
-l
-R
-r tag
In addition to the above, these options are available:
-c
-s
-t
-u
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
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
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 section The 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.
The release command supports one command option:
-d
release command deletes
all directories and files recursively. 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 section Adding files to a directory) will be silently deleted--even
if it is non-empty!
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 section Adding files to a directory) will be
silently ignored (and deleted, if `-d' is
specified), even if they contain files.
U file
P file
A file
R file
M file
? file
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
$
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 section tag--Add a symbolic tag to checked out versions of files), 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.
These standard options are supported by rtag
(see section Common command options, for a complete description of
them):
-D date
-f
-F
-l
-n
-R
-r tag
In addition to the above common options, these options are available:
-a
rtag look in the
`Attic' (see section The attic) 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
-d
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.
These standard options are supported by tag
(see section Common command options, for a complete description of
them):
-F
-l
-R
Two special options are available:
-b
-c
-d
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.
These standard options are available with update
(see section Common command options, for a complete description of
them):
-D date
-f
-k kflag
status command can be viewed
to see the sticky options. See section Quick reference to CVS commands, for
more information on the status command.
-l
-P
-p
-R
-r rev
These special options are also available with
update.
-A
-d
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
-Wspec
-jrevision
update and checkout keep you informed of
their progress by printing a line for each file, preceded
by one character indicating the status of the file:
U file
P file
A file
commit on the file. This is a
reminder to you that the file needs to be committed.
R file
commit on the file. This is a
reminder to you that the file needs to be committed.
M file
update) will be made. The exact
name of that file is printed while update runs.
C file
? file
This appendix describes how to invoke CVS, with
references to where each command or feature is
described in detail. For other references run the
cvs --help command, or see section Index.
A CVS command looks like:
cvs [ global_options ] command [ command_options ] [ command_args ]
Global options:
--allow-root=rootdir
-a
-b
-d root
-e editor
-f
-H
--help
-l
-n
-Q
-q
-r
-s variable=value
-T tempdir
-t
-v
--version
-w
-x
-z gzip-level
Keyword expansion modes (see section Substitution modes):
-kkv $Id: file1,v 1.1 1993/12/09 03:21:13 joe Exp $ -kkvl $Id: file1,v 1.1 1993/12/09 03:21:13 joe Exp harry $ -kk $Id$ -kv file1,v 1.1 1993/12/09 03:21:13 joe Exp -ko no expansion -kb no expansion, file is binary
Keywords (see section Keyword List):
$Author: joe $ $Date: 1993/12/09 03:21:13 $ $Header: /home/files/file1,v 1.1 1993/12/09 03:21:13 joe Exp harry $ $Id: file1,v 1.1 1993/12/09 03:21:13 joe Exp harry $ $Locker: harry $ $Name: snapshot_1_14 $ $RCSfile: file1,v $ $Revision: 1.1 $ $Source: /home/files/file1,v $ $State: Exp $ $Log: file1,v $ Revision 1.1 1993/12/09 03:30:17 joe Initial revision
Commands, command options, and command arguments:
add [options] [files...]
-k kflag
-m msg
admin [options] [files...]
-b[rev]
-cstring
-ksubst
-l[rev]
-mrev:msg
-orange
-q
-sstate[:rev]
-t
-tfile
-t-string
-u[rev]
annotate [options] [files...]
-D date
-f
-l
-R
-r tag
checkout [options] modules...
-A
-c
-D date
-d dir
-f
-j rev
-k kflag
-l
-N
-n
-P
-p
-R
-r tag
-s
commit [options] [files...]
-F file
-f
-l
-m msg
-n
-R
-r rev
diff [options] [files...]
-D date1
-D date2
-l
-N
-R
-r rev1
-r rev2
edit [options] [files...]
-a actions
edit, unedit,
commit, all, or none. See
section How to edit a file which is being watched.
-l
-R
editors [options] [files...]
-l
-R
export [options] modules...
-D date
-d dir
-f
-k kflag
-l
-N
-n
-P
-R
-r tag
history [options] [files...]
-a
-b str
-c
-D date
-e
-l
-m module
-n module
-o
-r rev
-T
-t tag
-u user
-w
-x types
TOEFWUCGMAR. See section history options.
-z zone
import [options] repository vendor-tag release-tags...
-b bra
-d
-k kflag
-m msg
-I ign
-W spec
init
log [options] [files...]
-b
-d dates
-h
-l
-N
-R
-rrevs
-s states
-t
-wlogins
login
logout
rdiff [options] modules...
-c
-D date
-f
-l
-R
-r rev
-s
-t
-u
-V vers
release [options] directory
-d
remove [options] [files...]
-f
-l
-R
rtag [options] tag modules...
-a
-b
-D date
-d
-F
-f
-l
-n
-R
-r tag
status [options] files...
-l
-R
-v
tag [options] tag [files...]
-b
-D date
-d
-F
-f
-l
-n
-R
-r tag
unedit [options] [files...]
-a actions
edit, unedit,
commit, all, or none. See
section How to edit a file which is being watched.
-l
-R
update [options] [files...]
-A
-D date
-d
-f
-I ign
-j rev
-k kflag
-l
-P
-p
-R
-r tag
-W spec
watch [on|off|add|remove] [options] [files...]
-a actions
edit, unedit,
commit, all, or none. See
section How to edit a file which is being watched.
-l
-R
watchers [options] [files...]
-l
-R
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 section The administrative files.
The most important of these files is the `modules' file, which defines the modules inside the repository.
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.
There are three basic types of modules: alias modules, regular modules, and ampersand modules. The difference between them is the way that they map files in the repository to files in the working directory. In all of the following examples, the top-level repository contains a directory called `first-dir', which contains two files, `file1' and `file2', and a directory `sdir'. `first-dir/sdir' contains a file `sfile'.
Alias modules are the simplest kind of module:
mname -a aliases...
checkout
creates all intermediate directories in the working
directory, just as if the path had been specified
explicitly in the CVS arguments.
For example, if the modules file contains:
amodule -a first-dir
then the following two commands are equivalent:
$ cvs co amodule $ cvs co first-dir
and they each would provide output such as:
cvs checkout: Updating first-dir U first-dir/file1 U first-dir/file2 cvs checkout: Updating first-dir/sdir U first-dir/sdir/sfile
mname [ options ] dir [ files... ]
$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.
For example, if a module is defined by:
regmodule first-dir
then regmodule will contain the files from first-dir:
$ cvs co regmodule cvs checkout: Updating regmodule U regmodule/file1 U regmodule/file2 cvs checkout: Updating regmodule/sdir U regmodule/sdir/sfile $
By explicitly specifying files in the module definition after dir, you can select particular files from directory dir. Here is an example:
regfiles first-dir/sdir sfile
With this definition, getting the regfiles module will create a single working directory `regfiles' containing the file listed, which comes from a directory deeper in the CVS source repository:
$ cvs co regfiles U regfiles/sfile $
A module definition can refer to other modules by including `&module' in its definition.
mname [ options ] &module...
Then getting the module creates a subdirectory for each such module, in the directory containing the module. For example, if modules contains
ampermod &first-dir
then a checkout will create an ampermod directory
which contains a directory called first-dir,
which in turns contains all the directories and files
which live there. For example, the command
$ cvs co ampermod
will create the following files:
ampermod/first-dir/file1 ampermod/first-dir/file2 ampermod/first-dir/sdir/sfile
There is one quirk/bug: the messages that CVS prints omit the `ampermod', and thus do not correctly display the location to which it is checking out the files:
$ cvs co ampermod cvs checkout: Updating first-dir U first-dir/file1 U first-dir/file2 cvs checkout: Updating first-dir/sdir U first-dir/sdir/sfile $
Do not rely on this buggy behavior; it may get fixed in a future release of CVS.
An alias module may exclude particular directories from other modules by using an exclamation mark (`!') before the name of each directory to be excluded.
For example, if the modules file contains:
exmodule -a !first-dir/sdir first-dir
then checking out the module `exmodule' will check out everything in `first-dir' except any files in the subdirectory `first-dir/sdir'.
Either regular modules or ampersand modules can contain options, which supply additional information concerning the module.
-d name
-e prog
-i prog
-o prog
-s status
-t prog
rtag. prog runs
with two arguments: the module name and the symbolic
tag specified to rtag. It is not run
when tag is executed. Generally you will find
that taginfo is a better solution (see section User-defined logging).
-u prog
Wrappers allow you to set a hook which transforms files on their way in and out of 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 `-t'/`-f' feature does
not work with client/server CVS.
The `cvswrappers' also has a `-m' option to
specify the merge methodology that should be used when
a non-binary file is updated. MERGE means the usual
CVS behavior: try to merge the files. COPY
means that cvs update will refuse to merge
files, as it also does for files specified as binary
with `-kb' (but if the file is specified as
binary, there is no need to specify `-m 'COPY'').
CVS will provide the user with the
two versions of the files, and require the user using
mechanisms outside CVS, to insert any necessary
changes. WARNING: do not use COPY with
CVS 1.9 or earlier--such versions of CVS will
copy one version of your file over the other, wiping
out the previous contents.
The `-m' wrapper option only affects behavior when
merging is done on update; it does not affect how files
are stored. See section Handling 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
.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 user's directory
that they can work on as they normally would.
Note that the `-t'/`-f' features do not
conveniently handle one portion of CVS's operation:
determining when files are modified. CVS will still
want a file (or directory) to exist, and it will use
its modification time to determine whether a file is
modified. If CVS erroneously thinks a file is
unmodified (for example, a directory is unchanged but
one of the files within it is changed), you can force
it to check in the file anyway by specifying the
`-f' option to cvs commit (see section commit options).
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 `-i' flag in the `modules' file can be used to run a certain program whenever files are committed (see section The modules file). 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.
The administrative files such as `commitinfo', `loginfo', `rcsinfo', `verifymsg', etc., 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:
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.
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 section Remote repositories).
Once you have entered a log message, you can evaluate that message to check for specific content, such as a bug ID. Use the `verifymsg' file to specify a program that is used to verify the log message. This program could be a simple script that checks that the entered message contains the required fields.
The `verifymsg' file is often most useful together with the `rcsinfo' file, which can be used to specify a log message template.
Each line in the `verifymsg' 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 verification 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 verification script exits with a non-zero exit status, the commit is aborted.
Note that the verification script cannot change the log message; it can merely accept it or reject it.
The following is a little silly example of a `verifymsg' file, together with the corresponding `rcsinfo' file, the log message template and an verification 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.verify' is used to evaluate the log message.
#!/bin/sh
#
# bugid.verify filename
#
# Verify that the log message contains a valid bugid
# on the first line.
#
if head -1 < $1 | grep '^BugId:[ ]*[0-9][0-9]*$' > /dev/null; then
exit 0
else
echo "No BugId found."
exit 1
fi
The `verifymsg' file contains this line:
^tc /usr/cvssupport/bugid.edit
The `rcsinfo' file contains this line:
^tc /usr/cvssupport/tc.template
NOTE: The `editinfo' feature has been
rendered obsolete. To set a default editor for log
messages use the EDITOR environment variable
(see section All environment variables which affect CVS) or the `-e' global
option (see section Global options). See section Verifying log messages,
for information on the use of the `verifymsg'
feature for evaluating log messages.
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 default will be used. See section Committing your changes.
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; use
`verifymsg' instead.
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
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 $CVSROOT. If a match is found, then
the remainder of the line is a filter program that
should expect log information on its standard input.
If the repository name does not match any of the regular expressions in this file, the `DEFAULT' line is used, if it is specified.
All occurances of the name `ALL' appearing as a regular expression are used in addition to the first matching regular expression or `DEFAULT'.
The first matching regular expression is used.
See section The commit support files, for a description of the syntax of the `loginfo' file.
The user may specify a format string as part of the filter. The string is composed of a `%' followed by a space, or followed by a single format character, or followed by a set of format characters surrounded by `{' and `}' as separators. The format characters are:
All other characters that appear in a format string expand to an empty field (commas separating fields are still provided).
For example, some valid format strings are `%', `%s', `%{s}', and `%{sVv}'.
The output will be a string of tokens separated by spaces. For backwards compatibility, the first token will be the repository name. The rest of the tokens will be comma-delimited lists of the information requested in the format string. For example, if `/u/src/master' is the repository, `%{sVv}' is the format string, and three files (ChangeLog, Makefile, foo.c) were modified, the output might be:
/u/src/master ChangeLog,1.1,1.2 Makefile,1.3,1.4 foo.c,1.12,1.13
As another example, `%{}' means that only the name of the repository will be generated.
Note: when CVS is accessing a remote repository, `loginfo' will be run on the remote (i.e., server) side, not the client side (see section Remote repositories).
The following `loginfo' file, together with the tiny shell-script below, appends all log messages to the file `$CVSROOT/CVSROOT/commitlog', and any commits to the administrative files (inside the `CVSROOT' directory) are also logged in `/usr/adm/cvsroot-log'. Commits to the `prog1' directory are mailed to ceder.
ALL /usr/local/bin/cvs-log $CVSROOT/CVSROOT/commitlog $USER ^CVSROOT /usr/local/bin/cvs-log /usr/adm/cvsroot-log ^prog1 Mail -s %s ceder
The shell-script `/usr/local/bin/cvs-log' looks like this:
#!/bin/sh (echo "------------------------------------------------------"; echo -n $2" "; date; echo; cat) >> $1
It is often useful to maintain a directory tree which contains files which correspond to the latest version in the repository. For example, other developers might want to refer to the latest sources without having to check them out, or you might be maintaining a web site with CVS and want every checkin to cause the files used by the web server to be updated.
The way to do this is by having loginfo invoke
cvs update. Doing so in the naive way will
cause a problem with locks, so the cvs update
must be run in the background.
Here is an example for unix (this should all be on one line):
^cyclic-pages (date; cat; (sleep 2; cd /u/www/local-docs; cvs -q update -d) &) >> $CVSROOT/CVSROOT/updatelog 2>&1
This will cause checkins to repository directories
starting with cyclic-pages to update the checked
out tree in `/u/www/local-docs'.
The `rcsinfo' file can be used to specify a form to edit when filling out the commit log. The `rcsinfo' file has a syntax similar to the `verifymsg', `commitinfo' and `loginfo' files. See section The common syntax. Unlike the other files the second part is not a command-line template. Instead, the part after the regular expression should be a full pathname to a file containing the log message template.
If the repository name does not match any of the regular expressions in this file, the `DEFAULT' line is used, if it is specified.
All occurances of the name `ALL' appearing as a regular expression are used in addition to the first matching regular expression or `DEFAULT'.
The log message template will be used as a default log message. If you specify a log message with `cvs commit -m message' or `cvs commit -f file' that log message will override the template.
See section Verifying log messages, for an example `rcsinfo' file.
When CVS is accessing a remote repository, the contents of `rcsinfo' at the time a directory is first checked out will specify a template which does not then change. If you edit `rcsinfo' or its templates, you may need to check out a new working directory.
There are certain file names that frequently occur inside your working copy, but that you don't want to put under CVS control. Examples are all the object files that you get while you compile your sources. Normally, when you run `cvs update', it prints a line for each file it encounters that it doesn't know about (see section update output).
CVS has a list of files (or sh(1) file name patterns)
that it should ignore while running update,
import and release.
This list is constructed in the following way.
RCS SCCS CVS CVS.adm
RCSLOG cvslog.*
tags TAGS
.make.state .nse_depinfo
*~ #* .#* ,* _$* *$
*.old *.bak *.BAK *.orig *.rej .del-*
*.a *.olb *.o *.obj *.so *.exe
*.Z *.elc *.ln
core
$CVSIGNORE is appended to the list.
In any of the 5 places listed above, a single exclamation mark (`!') clears the ignore list. This can be used if you want to store any file which normally is ignored by CVS.
Specifying `-I !' to cvs import will import
everything, which is generally what you want to do if
you are importing files from a pristine distribution or
any other source which is known to not contain any
extraneous files. However, looking at the rules above
you will see there is a fly in the ointment; if the
distribution contains any `.cvsignore' files, then
the patterns from those files will be processed even if
`-I !' is specified. The only workaround is to
remove the `.cvsignore' files in order to do the
import. Because this is awkward, in the future
`-I !' might be modified to override
`.cvsignore' files in each directory.
Note that the syntax of the ignore files consists of a series of lines, each of which contains a space separated list of filenames. This offers no clean way to specify filenames which contain spaces, but you can use a workaround like `foo?bar' to match a file named `foo bar' (it also matches `fooxbar' and the like). Also note that there is currently no way to specify comments.
The file `$CVSROOT/CVSROOT/history' is used
to log information for the history command
(see section history--Show status of files and users). 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 section 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.
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 reasonable
expansion if pserver (see section Direct connection with password authentication)
is in use; 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
RCSBIN
CVSEDITOR
VISUAL
EDITOR
USER
If you want to pass a value to the administrative files
which the user who 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 section Default options and the ~/.cvsrc file).
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.
The administrative file `config' contains various miscellaneous settings which affect the behavior of CVS. The syntax is slightly different from the other administrative files. Variables are not expanded. Lines which start with `#' are considered comments. Other lines consist of a keyword, `=', and a value. Note that this syntax is very strict. Extraneous spaces or tabs are not permitted.
Currently defined keywords are:
RCSBIN=bindir
SystemAuth=value
PreservePermissions=value
TopLevelAdmin=value
This is a complete list of all environment variables that affect CVS.
$CVSIGNORE
$CVSWRAPPERS
$CVSREAD
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.
$CVSUMASK
$CVSROOT
$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
$CVSEDITOR overrides
$EDITOR. See section Committing your changes.
$PATH
$RCSBIN is not set, and no path is compiled
into CVS, it will use $PATH to try to find all
programs it uses.
$HOME
$HOMEPATH
$HOMEDRIVE
$CVS_RSH
:ext: access method is specified.
see section Connecting with rsh.
$CVS_SERVER
cvs. see section Connecting with rsh
$CVS_PASSFILE
cvs
login server. Default value is `$HOME/.cvspass'.
see section Using the client with password authentication
$CVS_CLIENT_PORT
$CVS_RCMD_PORT
$CVS_CLIENT_LOG
$CVS_CLIENT_LOG.in' and everything
send from the server is logged into
`$CVS_CLIENT_LOG.out'.
$CVS_SERVER_SLEEP
$CVS_IGNORE_REMOTE_ROOT
$COMSPEC
$TMPDIR
$TMP
$TEMP
TMPDIR. See section Global options, for a
description of how to specify this.
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). Note that
if your server and client are both running CVS
1.9.10 or later, CVS will not invoke an external
patch program.
The repository format is compatible going back to CVS 1.3. But see section Using watches with old versions of CVS, if you have copies of CVS 1.6 or older and you want to use the optional developer communication features.
The working directory format is compatible going back to CVS 1.5. It did change between CVS 1.3 and CVS 1.5. If you run CVS 1.5 or newer on a working directory checked out with CVS 1.3, CVS will convert it, but to go back to CVS 1.3 you need to check out a new working directory with CVS 1.3.
The remote protocol is interoperable going back to CVS 1.5, but no further (1.5 was the first official release with the remote protocol, but some older versions might still be floating around). In many cases you need to upgrade both the client and the server to take advantage of new features and bugfixes, however.
If you are having trouble with CVS, this appendix may help. If there is a particular error message which you are seeing, then you can look up the message alphabetically. If not, you can look through the section on other problems to see if your problem is mentioned there.
Here is a partial list of error messages that you may see from CVS. It is not a complete list---CVS is capable of printing many, many error messages, often with parts of them supplied by the operating system, but the intention is to list the common and/or potentially confusing error messages.
The messages are alphabetical, but introductory text such as `cvs update: ' is not considered in ordering them.
In some cases the list includes messages printed by old versions of CVS (partly because users may not be sure which version of CVS they are using at any particular moment).
cvs command: authorization failed: server host rejected access
file:line: Assertion 'text' failed
cvs command: conflict: removed file was modified by second party
cannot change permissions on temporary directory
Operation not permittedThis message has been happening in a non-reproducible, occasional way when we run the client/server testsuite, both on Red Hat Linux 3.0.3 and 4.1. We haven't been able to figure out what causes it, nor is it known whether it is specific to linux (or even to this particular machine!). If the problem does occur on other unices, `Operation not permitted' would be likely to read `Not owner' or whatever the system in question uses for the unix
EPERM error. If
you have any information to add, please let us know as
described in section Dealing with bugs in CVS or this manual. If you experience this error
while using CVS, retrying the operation which
produced it should work fine.
cannot open CVS/Entries for reading: No such file or directory
cvs [init aborted]: cannot open CVS/Root: No such file or directory
cvs [checkout aborted]: cannot rename file file to CVS/,,file: Invalid argument
cvs [command aborted]: cannot start server via rcmd
:local:, as described in section The Repository.
ci: file,v: bad diff output line: Binary files - and /tmp/T2a22651 differ
cvs checkout: could not check out file
co program
(part of RCS) returned a failure. It should be
preceded by another error message, however it has been
observed without another error message and the cause is
not well-understood. With the current version of CVS,
which does not run co, if this message occurs
without another error message, it is definitely a CVS
bug (see section Dealing with bugs in CVS or this manual).
cvs [login aborted]: could not find out home directory
cvs update: could not merge revision rev of file: No such file or directory
rcsmerge program. Make
sure that it is in your PATH, or upgrade to a
current version of CVS, which does not require
an external rcsmerge program.
cvs [update aborted]: could not patch file: No such file or directory
patch program. Make sure that it is in your
PATH. Note that despite appearances the message
is not referring to whether it can find file.
If both the client and the server are running a current
version of CVS, then there is no need for an
external patch program and you should not see this
message. But if either client or server is running
CVS 1.9, then you need patch.
cvs update: could not patch file; will refetch
dying gasps from server unexpected
end of file from server (consult above messages if any)
rsh program and it exited with
an error. In this case the rsh program should
have printed a message, which will appear before the
above message. For more information on setting up a
CVS client and server, see section Remote repositories.
cvs commit: Executing 'mkmodules'
cvs commit: Rebuilding administrative file databaseIf you see both messages, the database is being rebuilt twice, which is unnecessary but harmless. If you wish to avoid the duplication, and you have no versions of CVS 1.7 or earlier in use, remove
-i mkmodules
every place it appears in your modules
file. For more information on the modules file,
see section The modules file.
missing author
*PANIC* administration files missing
rcs error: Unknown option: -x,v/
cvs [server aborted]: received broken pipe signal
Too many arguments!
cvs commit: Up-to-date check failed for `file'
cvs
update. So before proceeding with your cvs
commit you need to cvs update. CVS will merge
the changes that you made and the changes that the
other person made. If it does not detect any conflicts
it will report `M cacErrCodes.h' and you are ready
to cvs commit. If it detects conflicts it will
print a message saying so, will report `C cacErrCodes.h',
and you need to manually resolve the
conflict. For more details on this process see
section Conflicts example.
Usage: diff3 [-exEX3 [-i | -m] [-L label1 -L label3]] file1 file2 file3
Only one of [exEX3] allowedThis indicates a problem with the installation of
diff3 and rcsmerge. Specifically
rcsmerge was compiled to look for GNU diff3, but
it is finding unix diff3 instead. The exact text of
the message will vary depending on the system. The
simplest solution is to upgrade to a current version of
CVS, which does not rely on external
rcsmerge or diff3 programs.
warning: unrecognized response `text' from cvs server
cvs commit: warning: editor session failed
#!/bin/sh vi $* exit 0
This section concerns what to do if you are having trouble making a connection to a CVS server. If you are running the CVS command line client running on Windows, first upgrade the client to CVS 1.9.12 or later. The error reporting in earlier versions provided much less information about what the problem was. If the client is non-Windows, CVS 1.9 should be fine.
If the error messages are not sufficient to track down the problem, the next steps depend largely on which access method you are using.
:ext:
:server:
:pserver:
cvs [pserver aborted]: bad auth protocol start: fooIf this fails to work, then make sure inetd is working right. Change the invocation in inetd.conf to run the echo program instead of cvs. For example:
2401 stream tcp nowait root /bin/echo echo helloAfter making that change and instructing inetd to re-read its configuration file, "telnet servername 2401" should show you the text hello and then the server should close the connection. If this doesn't work, you need to fix it before you can worry about CVS problems. On AIX systems, the system will often have its own program trying to use port 2401. This is AIX's problem in the sense that port 2401 is registered for use with CVS. I hear that there is an AIX patch available to address this problem.
Here is a list of problems which do not fit into the above categories. They are in no particular order.
cvs update finds a conflict and tries to
merge, as described in section Conflicts example, but
doesn't tell you there were conflicts, then you may
have an old version of RCS. The easiest solution
probably is to upgrade to a current version of
CVS, which does not rely on external RCS
programs.
Roland Pesch, then of Cygnus Support <roland@wrs.com> wrote the manual pages which were distributed with CVS 1.3. Much of their text was copied into this manual. 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 is 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>.
The list of contributors here is not comprehensive; for a more complete list of who has contributed to this manual see the file `doc/ChangeLog' in the CVS source distribution.
Neither CVS nor this manual is perfect, and they probably never will be. If you are having trouble using CVS, or think you have found a bug, there are a number of things you can do about it. Note that if the manual is unclear, that can be considered a bug in the manual, so these problems are often worth doing something about as well as problems with CVS itself.
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 http://www.signum.se/ Cyclic Software United States of America http://www.cyclic.com/ info@cyclic.com
http://www.cyclic.com http://www.loria.fr/~molli/cvs-index.htmlIf you are so inspired, increasing the information available on the net is likely to be appreciated. For example, before the standard CVS distribution worked on Windows 95, there was a web page with some explanation and patches for running CVS on Windows 95, and various people helped out by mentioning this page on mailing lists or newsgroups when the subject came up.
bug-cvs.
Note that someone may or may not want to do anything
with your bug report--if you need a solution consider
one of the options mentioned above. People probably do
want to hear about bugs which are particularly severe
in consequences and/or easy to fix, however. You can
also increase your odds by being as clear as possible
about the exact nature of the bug and any other
relevant information. The way to report bugs is to
send email to bug-cvs@gnu.org. Note
that submissions to bug-cvs may be distributed
under the terms of the GNU Public License, so if
you don't like this, don't submit them. There is
usually no justification for sending mail directly to
one of the CVS maintainers rather than to
bug-cvs; those maintainers who want to hear
about such bug reports read bug-cvs. Also note
that sending a bug report to other mailing lists or
newsgroups is not a substitute for sending it to
bug-cvs. It is fine to discuss CVS bugs on
whatever forum you prefer, but there are not
necessarily any maintainers reading bug reports sent
anywhere except bug-cvs.
People often ask if there is a list of known bugs or whether a particular bug is a known one. The file BUGS in the CVS source distribution is one list of known bugs, but it doesn't necessarily try to be comprehensive. Perhaps there will never be a comprehensive, detailed list of known bugs.
This document was generated on 7 August 1998 using the texi2html translator version 1.51.