START-INFO-DIR-ENTRY * CVS: (cvs). Concurrent Versions System END-INFO-DIR-ENTRY
Copyright © 1992, 1993 Signum Support AB Copyright © 1993, 1994 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.
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This info manual describes how to use and administer CVS version 1.10.
CVS and the Real World. -----------------------
References. -----------
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 BUGS. 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.
Makefiles), they are essentially
independent.
CVS does not dictate how you build anything. It merely stores files for retrieval in a tree structure you devise.
CVS does not dictate how to use disk space in the
checked out working directories. If you write your
Makefiles or scripts in every directory so they
have to know the relative positions of everything else,
you wind up requiring the entire repository to be
checked out.
If you modularize your work, and construct a build
system that will share files (via links, mounts,
VPATH in Makefiles, etc.), you can
arrange your disk usage however you like.
But you have to remember that any such system is a lot of work to construct and maintain. CVS does not address the issues involved.
Of course, you should place the tools created to
support such a build system (scripts, Makefiles,
etc) under CVS.
Figuring out what files need to be rebuilt when
something changes is, again, something to be handled
outside the scope of CVS. One traditional
approach is to use make for building, and use
some automated tool for generating the dependencies which
make uses.
See Builds, for more information on doing builds
in conjunction with CVS.
CVS is an instrument for making sources dance to
your tune. But you are the piper and the composer. No
instrument plays itself or writes its own music.
CVS cannot determine when simultaneous changes
within a single file, or across a whole collection of
files, will logically conflict with one another. Its
concept of a conflict is purely textual, arising
when two changes to the same base file are near enough
to spook the merge (i.e. diff3) command.
CVS does not claim to help at all in figuring out non-textual or distributed conflicts in program logic.
For example: Say you change the arguments to function
X defined in file A. At the same time,
someone edits file B, adding new calls to
function X using the old arguments. You are
outside the realm of CVS's competence.
Acquire the habit of reading specs and talking to your
peers.
rcsinfo and verifymsg files
(see Administrative files).
Another aspect of change control is keeping track of
the fact that changes to several files were in fact
changed together as one logical change. If you check
in several files in a single cvs commit
operation, CVS then forgets that those files were
checked in together, and the fact that they have the
same log message is the only thing tying them
together. Keeping a GNU style ChangeLog
can help somewhat.
Another aspect of change control, in some systems, is
the ability to keep track of the status of each
change. Some changes have been written by a developer,
others have been reviewed by a second developer, and so
on. Generally, the way to do this with CVS is to
generate a diff (using cvs diff or diff)
and email it to someone who can then apply it using the
patch utility. This is very flexible, but
depends on mechanisms outside CVS to make sure
nothing falls through the cracks.
commitinfo file. I haven't
heard a lot about projects trying to do that or whether
there are subtle gotchas, however.
commitinfo,
loginfo, rcsinfo, or verifymsg
files, to require that certain steps be performed
before cvs will allow a checkin. Also consider whether
features such as branches and tags can be used to
perform tasks such as doing work in a development tree
and then merging certain changes over to a stable tree
only once they have been proven.
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 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 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 release):
$ cd .. $ cvs release -d tc M driver.c ? tc You have [1] altered files in this repository. Are you sure you want to release (and delete) module `tc': n ** `release' aborted by user choice.
The release command checks that all your modifications have been
committed. If history logging is enabled it also makes a note in the
history file. See history file.
When you use the -d flag with release, it
also removes your working copy.
In the example above, the release command wrote a couple of lines
of output. ? tc means that the file tc is unknown to CVS.
That is nothing to worry about: tc is the executable compiler,
and it should not be stored in the repository. See cvsignore,
for information about how to make that warning go away.
See release output, for a complete explanation of
all possible output from release.
M driver.c is more serious. It means that the
file driver.c has been modified since it was
checked out.
The release command always finishes by telling
you how many modified files you have in your working
copy of the sources, and then asks you for confirmation
before deleting any files or making any note in the
history file.
You decide to play it safe and answer n <RET>
when release asks for confirmation.
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 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 Concurrency) 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 Magic branch numbers. Also in CVS the valid tag names are a subset of what RCS accepts; for CVS's rules see Tags.
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 Concurrency).
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, Setting a watch; -r, Global options; or CVSREAD, Environment variables).
Note that using the client/server CVS
(see 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 Password authentication security.
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 (Password authentication security).
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 BUGS.
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 Watches Compatibility.
For an introduction to CVS locks focusing on user-visible behavior, see Concurrency. The following section is aimed at people who are writing tools which want to access a CVS repository without interfering with other tools acessing 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 BUGS). 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 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.
Root
Repository
cvs -d :local:/usr/local/cvsroot checkout yoyodyne/tc
Root will contain
:local:/usr/local/cvsroot
and Repository will contain either
/usr/local/cvsroot/yoyodyne/tc
or
yoyodyne/tc
Entries
If the first character is /, then the format is:
/name/revision/timestamp[+conflict]/options/tagdate
where [ 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/filler4
where 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.
Entries.Log
Entries, but it does provide a way to update
the information without having to rewrite the entire
Entries file, including the ability to preserve
the information even if the program writing
Entries and Entries.Log abruptly aborts.
Programs which are reading the Entries file
should also check for Entries.Log. If the latter
exists, they should read Entries and then apply
the changes mentioned in Entries.Log. After
applying the changes, the recommended practice is to
rewrite Entries and then delete Entries.Log.
The format of a line in Entries.Log is a single
character command followed by a space followed by a
line in the format specified for a line in
Entries. The single character command is
A to indicate that the entry is being added,
R to indicate that the entry is being removed,
or any other character to indicate that the entire line
in Entries.Log should be silently ignored (for
future expansion). If the second character of the line
in Entries.Log is not a space, then it was
written by an older version of CVS (not documented
here).
Entries.Backup
Entries.Backup, and
then to rename it (atomically, where possible) to Entries.
Entries.Static
update command with the
-d option, which will get the additional files
and remove Entries.Static.
Tag
T for a branch tag,
N for a non-branch tag, or D for a date,
or another character to mean the file should be
silently ignored, for future expansion. This character
is followed by the tag or date. Note that
per-directory sticky tags or dates are used for things
like applying to files which are newly added; they
might not be the same as the sticky tags or dates on
individual files. For general information on sticky
tags and dates, see Sticky tags.
Checkin.prog
Update.prog
-i and -u options in the modules file,
respectively.
Notify
edit or unedit) which have not yet been
sent to the server. Its format is not yet documented
here.
Notify.tmp
Notify as Entries.Backup
is to Entries. That is, to write Notify,
first write the new contents to Notify.tmp and
then (atomically where possible), rename it to
Notify.
Base
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.
Baserev
Base directory. The format is:
Bname/rev/expansion
where expansion should be ignored, to allow for
future expansion.
Baserev.tmp
Baserev as Entries.Backup
is to Entries. That is, to write Baserev,
first write the new contents to Baserev.tmp and
then (atomically where possible), rename it to
Baserev.
Template
rcsinfo file (see rcsinfo). It is only used
by the client; the non-client/server CVS consults
rcsinfo directly.
The directory $CVSROOT/CVSROOT contains some administrative
files. See Administrative files, for a complete description.
You can use CVS without any of these files, but
some commands work better when at least the
modules file is properly set up.
The most important of these files is the modules
file. It defines all modules in the repository. This
is a sample modules file.
CVSROOT CVSROOT modules CVSROOT modules cvs gnu/cvs rcs gnu/rcs diff gnu/diff tc yoyodyne/tc
The modules file is line oriented. In its
simplest form each line contains the name of the
module, whitespace, and the directory where the module
resides. The directory is a path relative to
$CVSROOT. The last four lines in the example
above are examples of such lines.
The line that defines the module called modules
uses features that are not explained here.
See modules, for a full explanation of all the
available features.
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 Specifying a repository).
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 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 accessable (directly or via a networked file system) from all machines which want to use CVS in server or local mode; the client machines need not have any access to it other than via the CVS protocol. It is not possible to use CVS to read from a repository which one only has read access to; CVS needs to be able to create lock files (see Concurrency).
To create a repository, run the cvs init
command. It will set up an empty repository in the
CVS root specified in the usual way
(see Repository). For example,
cvs -d /usr/local/cvsroot init
cvs init is careful to never overwrite any
existing files in the repository, so no harm is done if
you run cvs init on an already set-up
repository.
cvs init will enable history logging; if you
don't want that, remove the history file after running
cvs init. See history file.
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 Concurrency, 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 directories, of
course).
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 Working directory storage, 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 Connecting via rsh.
rsh program to connect
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 BUGS, 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 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 Password authentication security, 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 Password authentication security, for details), a separate CVS password
file may be used, so people don't compromise their
regular passwords when they access the repository.
This file is $CVSROOT/CVSROOT/passwd
(see Intro administrative files). Its format is
similar to /etc/passwd, except that it only has
two 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 config). 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 Read-only access); however, also see Password authentication security. 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 Connecting via rsh).
(Once you have a working copy checked out and are
running CVS commands from within it, there is no
longer any need to specify the repository explicitly,
because CVS records it in the working copy's
CVS subdirectory.)
Passwords are stored by default in the file
$HOME/.cvspass. Its format is human-readable,
but don't edit it unless you know what you are doing.
The passwords are not stored in cleartext, but are
trivially encoded to protect them from "innocent"
compromise (i.e., inadvertently being seen by a system
administrator who happens to look at that file).
The 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 Password authentication server) allows people to use a different password for repository access than for login access. On the other hand, once a user has 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 Password authentication server. 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 config).
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 Connecting via 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 Password authenticated). (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 Password authentication server).
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 Password authentication server), 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 Environment variables), the -T global
option (see 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:
kill -KILL on unix).
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 Moving 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 Tracking sources, for
more information about them.
You can now verify that it worked, and remove your original source directory.
$ cd .. $ mv dir dir.orig $ cvs checkout yoyodyne/dir # Explanation below $ 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 File permissions.
If some of the files you want to import are binary, you may want to use the wrappers features to specify which files are binary and which are not. See Wrappers.
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.
foo.c will have its
RCS file in RCS/foo.c,v (but it could be
other places; consult the RCS documentation for
details). Then create the appropriate directories in
CVS if they do not already exist. Then copy the
files into the appropriate directories in the CVS
repository (the name in the repository must be the name
of the source file with ,v added; the files go
directly in the appopriate directory of the repository,
not in an RCS subdirectory). This is one of the
few times when it is a good idea to access the CVS
repository directly, rather than using CVS
commands. Then you are ready to check out a new
working directory.
The RCS file should not be locked when you move it
into CVS; if it is, CVS will have trouble
letting you operate on it.
Failing that, probably your best bet is to write a
script that will check out the files one revision at a
time using the command line interface to the other
system, and then check the revisions into CVS.
The sccs2rcs script mentioned below may be a
useful example to follow.
contrib directory of
the CVS source distribution called sccs2rcs
which converts SCCS files to RCS files.
Note: you must run it on a machine which has both
SCCS and RCS installed, and like everything
else in contrib it is unsupported (your mileage may
vary).
contrib directory of
the CVS source distribution called pvcs_to_rcs
which converts PVCS archives to RCS files.
You must run it on a machine which has both
PVCS and RCS installed, and like everything
else in contrib it is unsupported (your mileage may
vary). See the comments in the script for details.
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:
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 Branching and merging); such revision numbers
are explained in detail in 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 Tags). 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 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 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 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 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 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
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 Tags) and find the bug (which turns out to have a trivial fix). However, the current revision of the sources are in a state of flux and are not expected to be stable for at least another month. There is no way to make a bugfix release based on the newest sources.
The thing to do in a situation like this is to create a branch on the revision trees for all the files that make up release 1.0 of tc. You can then make modifications to the branch without disturbing the main trunk. When the modifications are finished you can 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 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 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 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 Branches and revisions for details about how branch numbers are constructed.
Ordinarily, a file's revision history is a linear series of increments (see 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 Magic branch numbers). The branch 1.1.1 has a special meaning. See Tracking 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 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).
The -j stands for "join".
Consider this revision tree:
+-----+ +-----+ +-----+ +-----+
! 1.1 !----! 1.2 !----! 1.3 !----! 1.4 ! <- The main trunk
+-----+ +-----+ +-----+ +-----+
!
!
! +---------+ +---------+
Branch R1fix -> +---! 1.2.2.1 !----! 1.2.2.2 !
+---------+ +---------+
The branch 1.2.2 has been given the tag (symbolic name) R1fix. The
following example assumes that the module mod contains only one
file, m.c.
$ cvs checkout mod # Retrieve the latest revision, 1.4
$ cvs update -j R1fix m.c # Merge all changes made on the branch,
# i.e. the changes between revision 1.2
# and 1.2.2.2, into your working copy
# of the file.
$ cvs commit -m "Included R1fix" # Create revision 1.5.
A conflict can result from a merge operation. If that happens, you should resolve it before committing the new revision. See Conflicts example.
The checkout command also supports the -j branch flag. The
same effect as above could be achieved with this:
$ cvs checkout -j R1fix mod $ cvs commit -m "Included R1fix"
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 is equivalent to
cvs update testing/testpgm.t testing/test2.t
cvs update testing man updates all files in the
subdirectories
cvs update . or just cvs update updates
all files in the tc module
If no arguments are given to update it will
update all files in the current working directory and
all its subdirectories. In other words, . is a
default argument to update. This is also true
for most of the CVS subcommands, not only the
update command.
The recursive behavior of the CVS subcommands can be
turned off with the -l option.
Conversely, the -R option can be used to force recursion if
-l is specified in ~/.cvsrc (see ~/.cvsrc).
$ 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.
cvs add filename to tell CVS that you
want to version control the file. If the file contains
binary data, specify -kb (see Binary files).
cvs commit filename to actually check
in the file into the repository. Other developers
cannot see the file until you perform this step.
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
cvs add [-k kflag] [-m message] files ...
|
Command |
|
Schedule files to be added to the repository.
The files or directories specified with The added files are not placed in the source repository
until you use The The |
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 Branching and merging). You can later merge the additions to another branch if you want (see Merging adds and removals).
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.
cvs remove filename to tell CVS that
you really want to delete the file.
cvs commit filename to actually
perform the removal of the file from the repository.
When you commit the removal of the file, CVS
records the fact that the file no longer exists. It is
possible for a file to exist on only some branches and
not on others, or to re-add another file with the same
name later. CVS will correctly create or not create
the file, based on the -r and -D options
specified to checkout or update.
| cvs remove [options] files ... | Command |
|
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 Invoking CVS. |
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 Branching and merging). You can later merge the removals to another branch if you want (see Merging adds and removals).
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 Moving 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 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:
-rtag and not -Ddate
to retrieve the revisions.
Disadvantages:
The normal way to rename or move a directory is to
rename or move each file within it as described in
Outside. Then check out with the -P
option, as described in 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 log).
You can use the history file (see history file) to
log various CVS actions. To retrieve the
information from the history file, use the cvs
history command (see history).
You can customize CVS to log various kinds of
actions, in whatever manner you choose. These
mechanisms operate by executing a script at various
times. The script might append a message to a file
listing the information and the programmer who created
it, or send mail to a group of developers, or, perhaps,
post a message to a particular newsgroup. To log
commits, use the loginfo file (see loginfo).
To log commits, checkouts, exports, and tags,
respectively, you can also use the -i,
-o, -e, and -t options in the
modules file. For a more flexible way of giving
notifications to various users, which requires less in
the way of keeping centralized scripts up to date, use
the cvs watch add command (see Getting Notified); this command is useful even if you are not
using cvs watch on.
The taginfo file defines programs to execute
when someone executes a tag or rtag
command. The taginfo file has the standard form
for administrative files (see Administrative files), where each line is a regular expression
followed by a command to execute. The arguments passed
to the command are, in order, the tagname,
operation (add for tag,
mov for tag -F, and del for
tag -d), repository, and any remaining are
pairs of filename revision. A non-zero
exit of the filter program will cause the tag to be
aborted.
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
cvs annotate [-flR] [-r rev|-D date] files ...
|
Command |
|
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 |
The options to cvs annotate are listed in
Invoking CVS, and can be used to select the files
and revisions to annotate. The options are described
in more detail in Common 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 Multiple developers). The second is when one
merges explicitly with the update -j command
(see 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 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 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 Wrappers.
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 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 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
Invoking CVS. For information on its Sticky tag
and Sticky date output, see Sticky tags.
For information on its Sticky options output,
see the -k option in 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 Invoking CVS.
When you want to update or merge a file, use the update
command. For files that are not up to date this is roughly equivalent
to a checkout command: the newest revision of the file is
extracted from the repository and put in your working copy of the
module.
Your modifications to a file are never lost when you
use update. If no newer revision exists,
running update has no effect. If you have
edited the file, and a newer revision is available,
CVS will merge all changes into your working copy.
For instance, imagine that you checked out revision 1.4 and started
editing it. In the meantime someone else committed revision 1.5, and
shortly after that revision 1.6. If you run update on the file
now, CVS will incorporate all changes between revision 1.4 and 1.6 into
your file.
If any of the changes between 1.4 and 1.6 were made too
close to any of the changes you have made, an
overlap occurs. In such cases a warning is
printed, and the resulting file includes both
versions of the lines that overlap, delimited by
special markers.
See update, for a complete description of the
update command.
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 modules.
See loginfo. You can use these features of CVS
to, for instance, instruct CVS to mail a
message to all developers, or post a message to a local
newsgroup.
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 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.
cvs watch on [-lR] files ...
|
Command |
|
Specify that developers should run 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 If files is omitted, it defaults to the current directory. |
cvs watch off [-lR] files ...
|
Command |
|
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 |
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.
cvs watch add [-a action] [-lR] files ...
|
Command |
|
Add the current user to the list of people to receive notification of work done on files. The
The The files and options are processed as for the
|
cvs watch remove [-a action] [-lR] files ...
|
Command |
|
Remove a notification request established using |
When the conditions exist for notification, CVS
calls the notify administrative file. Edit
notify as one edits the other administrative
files (see Intro administrative files). This
file follows the usual conventions for administrative
files (see syntax), where each line is a regular
expression followed by a command to execute. The
command should contain a single ocurrence of %s
which will be replaced by the user to notify; the rest
of the information regarding the notification will be
supplied to the command on standard input. The
standard thing to put in the notify file is the
single line:
ALL mail %s -s \"CVS notification\"
This causes users to be notified by electronic mail.
Note that if you set this up in the straightforward
way, users receive notifications on the server machine.
One could of course write a notify script which
directed notifications elsewhere, but to make this
easy, CVS allows you to associate a notification
address for each user. To do so create a file
users in CVSROOT with a line for each
user in the format user:value. Then
instead of passing the name of the user to be notified
to notify, CVS will pass the value
(normally an email address on some other machine).
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 Getting the source), an operation which those systems call a
get or a fetch.
| cvs edit [options] files ... | Command |
|
Prepare to edit the working files files. CVS makes the
files read-write, and notifies users who have requested
The The files and options are processed as for the Caution: If the |
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.
cvs unedit [-lR] files ...
|
Command |
|
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
The files and options are processed as for the
If watches are not in use, the |
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.
cvs watchers [-lR] files ...
|
Command |
|
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 editors [-lR] files ...
|
Command |
|
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
|
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 Watches can be considered to be an intermediate model between reserved checkouts and unreserved checkouts. When you go to edit a file, it is possible to find out who else is editing it. And rather than having the system simply forbid both people editing the file, it can tell you what the situation is and let you figure out whether it is a problem in that particular case or not. Therefore, for some groups it can be considered the best of both the reserved checkout and unreserved checkout worlds.
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 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 Log keyword.
$RCSfile$
$Revision$
$Source$
$State$
cvs admin -s--see 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 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 Binary files.
The modes available are:
-kkv
$Revision: 5.7 $ for the Revision
keyword.
-kkvl
-kkv, except that a locker's name is always
inserted if the given revision is currently locked.
This option is normally not useful when CVS is used.
-kk
Revision
keyword, generate the string $Revision$
instead of $Revision: 5.7 $. This option
is useful to ignore differences due to keyword
substitution when comparing different revisions of a
file.
-ko
Revision keyword, generate the string
$Revision: 1.1 $ instead of
$Revision: 5.7 $ if that is how the
string appeared when the file was checked in.
-kb
-ko, but also inhibit conversion of line
endings between the canonical form in which they are
stored in the repository (linefeed only), and the form
appropriate to the operating system in use on the
client. For systems, like unix, which use linefeed
only to terminate lines, this is the same as
-ko. For more information on binary files, see
Binary files.
-kv
Revision keyword, generate the string
5.7 instead of $Revision: 5.7 $.
This can help generate files in programming languages
where it is hard to strip keyword delimiters like
$Revision: $ from a string. However,
further keyword substitution cannot be performed once
the keyword names are removed, so this option should be
used with care.
One often would like to use -kv with cvs
export--see export. But be aware that doesn't
handle an export containing binary files correctly.
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 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 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 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 admin options.
Use the -k wrapper option to tell import which
files are binary. See Wrappers.
The sources which you are importing may contain keywords (see 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 Tags).
Using CVS in the most straightforward manner possible, each developer will have a copy of the entire source tree which is used in a particular build. If the source tree is small, or if developers are geographically dispersed, this is the preferred solution. In fact one approach for larger projects is to break a project down into smaller separately-compiled subsystems, and arrange a way of releasing them internally so that each developer need check out only those subsystems which are they are actively working on.
Another approach is to set up a structure which allows
developers to have their own copies of some files, and
for other files to access source files from a central
location. Many people have come up with some such a
system using features such as the symbolic link feature
found in many operating systems, or the VPATH
feature found in many versions of make. One build
tool which is designed to help with this kind of thing
is Odin (see
ftp://ftp.cs.colorado.edu/pub/distribs/odin).
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 config) 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 Invoking CVS).
The overall format of all CVS commands is:
cvs [ cvs_options ] cvs_command [ command_options ] [ command_args ]
cvs
cvs_options
cvs_command
cvs_command: cvs -H elicits a
list of available commands, and cvs -v displays version
information on CVS itself.
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 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 Repository.
-e editor
$CVSEDITOR and $EDITOR
environment variables. For more information, see
Committing your changes.
-f
~/.cvsrc file. This
option is most often used because of the
non-orthogonality of the CVS option set. For
example, the cvs log option -N (turn off
display of tag names) does not have a corresponding
option to turn the display on. So if you have
-N in the ~/.cvsrc entry for log,
you may need to use -f to show the tag names.
-H
--help
cvs_command
(but do not actually execute the command). If you don't specify
a command name, cvs -H displays overall help for
CVS, including a list of other help options.
-l
cvs_command in the command history (but execute it
anyway). See history, for information on command history.
-n
cvs_command, but only to issue reports; do not remove,
update, or merge any existing files, or create any new files.
Note that CVS will not necessarily produce exactly
the same output as without -n. In some cases
the output will be the same, but in other cases
CVS will skip some of the processing that would
have been required to produce the exact same output.
-Q
-q
-r
$CVSREAD environment variable is set
(see Environment variables). The default is to
make working files writable, unless watches are on
(see Watches).
-s variable=value
-t
-n to explore the
potential impact of an unfamiliar command.
-v
--version
-w
$CVSREAD environment variable.
Files are created read-write by default, unless $CVSREAD is
set or -r is given.
-x
--enable-encryption,
when you build CVS.
-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
The specification is sticky when you use it to make a
private copy of a source file; that is, when you get a working
file using -D, CVS records the date you specified, so that
further updates in the same directory will use the same date
(for more information on sticky tags/dates, see Sticky tags).
-D is available with the checkout,
diff, export, history,
rdiff, rtag, and update commands.
(The history command uses this option in a
slightly different way; see history options).
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 20:05
For more details about ISO8601 dates, see:
http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html
In 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 Sep
The 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.txi
-f
-f option
if you want files retrieved even when there is no match for the
tag or date. (The most recent revision of the file
will be used).
-f is available with these commands:
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 commit options, and
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
Warning: this is not the same
as the overall cvs -l option, which you can specify to the
left of a cvs command!
Available with the following commands: annotate, checkout,
commit, diff, edit, editors, export,
log, rdiff, remove, rtag,
status, tag, unedit, update, watch,
and watchers.
-m message
Available with the following commands: add,
commit and import.
-n
Warning: this is not the same as the overall cvs -n
option, which you can specify to the left of a cvs command!
Available with the checkout, commit, export,
and rtag commands.
-P
-p
checkout and update commands.
-R
Available with the following commands: 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 Sticky tags). The
tag can be either a symbolic or numeric tag.
See Tags.
Specifying the -q global option along with the
-r command option is often useful, to suppress
the warning messages when the RCS 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
.cvswrappers file.
Available with the following commands: 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 Reverting local changes).
There can be no space between -b and its argument.
-cstring
-e[logins]
-I
-i
cvs add command
(see Adding files).
-ksubst
-k option to
cvs update, cvs export, or cvs
checkout overrides this default.
-l[rev]
-l and its argument.
This can be used in conjunction with the
rcslock.pl script in the contrib
directory of the CVS source distribution to
provide reserved checkouts (where only one user can be
editing a given file at a time). See the comments in
that file for details (and see the README file
in that directory for disclaimers about the unsupported
nature of contrib). According to comments in that
file, locking must set to strict (which is the default).
-L
-l option above.
-mrev:msg
-Nname[:[rev]]
-n, except override any previous
assignment of name. For use with magic branches,
see Magic branch numbers.
-nname[:[rev]]
cvs tag or cvs rtag instead. Delete the
symbolic name if both : and rev are
omitted; otherwise, print an error message if
name is already associated with another number.
If rev is symbolic, it is expanded before
association. A rev consisting of a branch number
followed by a . stands for the current latest
revision in the branch. A : with an empty
rev stands for the current latest revision on the
default branch, normally the trunk. For example,
cvs admin -nname: associates name with the
current latest revision of all the RCS files;
this contrasts with cvs admin -nname:$ which
associates name with the revision numbers
extracted from keyword strings in the corresponding
working files.
-orange
Note that this command can be quite dangerous unless you know exactly what you are doing (for example see the warnings below about how the rev1:rev2 syntax is confusing).
If you are short on disc this option might help you. But think twice before using it--there is no way short of restoring the latest backup to undo this command! If you delete different revisions than you planned, either due to carelessness or (heaven forbid) a CVS bug, there is no opportunity to correct the error before the revisions are deleted. It probably would be a good idea to experiment on a copy of the repository first.
Specify range in one of the following ways:
rev1::rev2
-o 1.3::1.5 one can retrieve
revision 1.3, revision 1.5, or the differences to get
from 1.3 to 1.5, but not the revision 1.4, or the
differences between 1.3 and 1.4. Other examples:
-o 1.3::1.4 and -o 1.3::1.3 have no
effect, because there are no intermediate revisions to
remove.
::rev
-o ::1.3.2.6 deletes revision 1.3.2.1,
revision 1.3.2.5, and everything in between, but leaves
1.3 and 1.3.2.6 intact.
rev::
rev
-o
1.3 is equivalent to -o 1.2::1.4.
rev1:rev2
cvs admin -oR_1_01:R_1_02 . is rarely useful.
It means to delete revisions up to, and including, the
tag R_1_02. But beware! If there are files that have not
changed between R_1_02 and R_1_03 the file will have
the same numerical revision number assigned to
the tags R_1_02 and R_1_03. So not only will it be
impossible to retrieve R_1_02; R_1_03 will also have to
be restored from the tapes! In most cases you want to
specify rev1::rev2 instead.
:rev
rev:
None of the revisions to be deleted may have branches or locks.
If any of the revisions to be deleted have symbolic
names, and one specifies one of the :: syntaxes,
then CVS will give an error and not delete any
revisions. If you really want to delete both the
symbolic names and the revisions, first delete the
symbolic names with 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 Magic branch numbers, for an explanation.
Make sure that no-one has checked out a copy of the
revision you outdate. Strange things will happen if he
starts to edit it and tries to check it back in. For
this reason, this option is not a good way to take back
a bogus commit; commit a new revision undoing the bogus
change instead (see Merging two revisions).
-q
-sstate[:rev]
Exp (for experimental), Stab (for
stable), and Rel (for released). By default,
the state of a new revision is set to Exp when
it is created. The state is visible in the output from
cvs log (see log), and in the
$Log$ and $State$ keywords
(see Keyword substitution). Note that CVS
uses the dead state for its own purposes; to
take a file to or from the dead state use
commands like cvs remove and cvs add, not
cvs admin -s.
-t[file]
-. The descriptive text can be seen in the
output from cvs log (see log).
There can be no space between -t and its argument.
If file is omitted,
obtain the text from standard input, terminated by
end-of-file or by a line containing . by itself.
Prompt for the text if interaction is possible; see
-I. Reading from standard input does not work
for client/server CVS and may change in a future
release of CVS.
-t-string
-tfile. Write descriptive text
from the string into the RCS file, deleting
the existing text.
There can be no space between -t and its argument.
-U
-l option
above.
-u[rev]
-l above, for a discussion of
using this option with CVS. Unlock the revision
with number rev. If a branch is given, unlock
the latest revision on that branch. If rev is
omitted, remove the latest lock held by the caller.
Normally, only the locker of a revision may unlock it.
Somebody else unlocking a revision breaks the lock.
This causes a mail message to be sent to the original
locker. The message contains a commentary solicited
from the breaker. The commentary is terminated by
end-of-file or by a line containing . by itself.
There can be no space between -u and its argument.
-Vn
-xsuffixes
,v, so
this option has never done anything useful.
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 modules.
Depending on the modules you specify, checkout may
recursively create directories and populate them with
the appropriate source files. You can then edit these
source files at any time (regardless of whether other
software developers are editing their own copies of the
sources); update them to include new changes applied by
others to the source repository; or commit your work as
a permanent change to the source repository.
Note that checkout is used to create
directories. The top-level directory created is always
added to the directory where checkout is
invoked, and usually has the same name as the specified
module. In the case of a module alias, the created
sub-directory may have a different name, but you can be
sure that it will be a sub-directory, and that
checkout will show the relative path leading to
each file as it is extracted into your private work
area (unless you specify the -Q global option).
The files created by checkout are created
read-write, unless the -r option to CVS
(see Global options) is specified, the
CVSREAD environment variable is specified
(see Environment variables), or a watch is in
effect for that file (see Watches).
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 update output.
These standard options are supported by checkout
(see Common options, for a complete description of
them):
-D date
-P. See
Sticky tags, for more information on sticky tags/dates.
-f
-D date or -r
tag flags. If no matching revision is found,
retrieve the most recent revision (instead of ignoring
the file).
-k kflag
status command can be viewed
to see the sticky options. See Invoking CVS, for
more information on the status command.
-l
-n
-o option in the modules file;
see modules).
-P
-p
-R
-r tag
-P.
See Sticky tags, for more information on sticky tags/dates.
In addition to those, you can use these special command
options with checkout:
-A
-k options.
See Sticky tags, for more information on sticky tags/dates.
-c
-d dir
mkdir
dir; cd dir followed by the checkout
command without the -d flag.
There is an important exception, however. It is very convenient when checking out a single item to have the output appear in a directory that doesn't contain empty intermediate directories. In this case only, CVS tries to "shorten" pathnames to avoid those empty directories.
For example, given a module foo that contains
the file bar.c, the command cvs co -d dir
foo will create directory dir and place
bar.c inside. Similarly, given a module
bar which has subdirectory baz wherein
there is a file quux.c, the command cvs -d
dir co bar/baz will create directory dir and
place quux.c inside.
Using the -N flag will defeat this behavior.
Given the same module definitions above, cvs co
-N -d dir foo will create directories dir/foo
and place bar.c inside, while cvs co -N -d
dir bar/baz will create directories dir/bar/baz
and place quux.c inside.
-j tag
-j options, merge changes from the
revision specified with the first -j option to
the revision specified with the second j option,
into the working directory.
With one -j option, merge changes from the
ancestor revision to the revision specified with the
-j option, into the working directory. The
ancestor revision is the common ancestor of the
revision which the working directory is based on, and
the revision specified in the -j option.
In addition, each -j option can contain an optional
date specification which, when used with branches, can
limit the chosen revision to one within a specific
date. An optional date is specified by adding a colon
(:) to the tag:
-jSymbolic_Tag:Date_Specifier.
-N
-d dir. With
this option, CVS will not "shorten" module paths
in your working directory when you check out a single
module. See the -d flag for examples and a
discussion.
-s
-c, but include the status of all modules,
and sort it by the status string. See modules, for
info about the -s option that is used inside the
modules file to set the module status.
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 update).
commit does not call the update command
for you, but rather leaves that for you to do when the
time is right.
When all is well, an editor is invoked to allow you to
enter a log message that will be written to one or more
logging programs (see modules, and see loginfo)
and placed in the RCS file inside the
repository. This log message can be retrieved with the
log command; see log. You can specify the
log message on the command line with the -m
message option, and thus avoid the editor invocation,
or use the -F file option to specify
that the argument file contains the log message.
These standard options are supported by commit
(see Common options, for a complete description of
them):
-l
-n
-R
-r revision
commit also supports these options:
-F file
-f
-f option as defined in Common options.
Force CVS to commit a new revision even if you haven't made any changes to the file. If the current revision of file is 1.7, then the following two commands are equivalent:
$ cvs commit -f file $ cvs commit -r 1.8 file
The -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 tag
or see rtag). Then, either checkout or
update can be used to base your sources on the
newly created branch. From that point on, all
commit changes made within these working sources
will be automatically added to a branch revision,
thereby not disturbing main-line development in any
way. For example, if you had to create a patch to the
1.2 version of the product, even though the 2.0 version
is already under development, you might do:
$ cvs rtag -b -r FCS1_2 FCS1_2_Patch product_module $ cvs checkout -r FCS1_2_Patch product_module $ cd product_module [[ hack away ]] $ cvs commit
This works automatically since the -r option is
sticky.
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 Exit status.
These standard options are supported by diff
(see Common options, for a complete description of
them):
-D date
-r for how this affects the comparison.
-k kflag
-l
-R
-r tag
-r options can be present. With no -r
option, the working file will be compared with the
revision it was based on. With one -r, that
revision will be compared to your current working file.
With two -r options those two revisions will be
compared (and your working file will not affect the
outcome in any way).
One or both -r options can be replaced by a
-D date option, described above.
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 Common 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
-d dir.
See checkout options, for complete details on how
CVS handles this flag.
$CVSROOT/CVSROOT/history
CVS can keep a history file that tracks each use of the
checkout, commit, rtag,
update, and release commands. You can
use history to display this information in
various formats.
Logging must be enabled by creating the file
$CVSROOT/CVSROOT/history.
Warning: history uses -f, -l,
-n, and -p in ways that conflict with the
normal use inside CVS (see Common options).
Several options (shown above as -report) control what
kind of report is generated:
-c
-e
-x with all record types. Of course,
-e will also include record types which are
added in a future version of CVS; if you are
writing a script which can only handle certain record
types, you'll want to specify -x.
-m module
-m more than once on the command line.)
-o
-T
-x type
Certain commands have a single record type:
F
O
E
T
One of four record types may result from an update:
C
G
U
W
One of three record types results from commit:
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
-D date, which
selects the newest revision older than date.
-p repository
-p options on the same command
line).
-r rev
-t tag
-r flag
above in that it reads only the history file, not the
RCS files, and is much faster.
-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 Tracking sources, for
a discussion on this subject.
The repository argument gives a directory name (or a path to a directory) under the CVS root directory for repositories; if the directory did not exist, import creates it.
When you use import for updates to source that has been
modified in your source repository (since a prior
import), it will notify you of any files that conflict
in the two branches of development; use checkout
-j to reconcile the differences, as import instructs
you to do.
If CVS decides a file should be ignored
(see cvsignore), it does not import it and prints
I followed by the filename (see 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 Wrappers.
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 Getting the source).
This standard option is supported by import
(see Common options, for a complete description):
-m message
There are the following additional special options.
-b branch
-k subst
-k settings.
-I name
name can be a file name pattern of the same type
that you can specify in the .cvsignore file.
See cvsignore.
-W spec
spec can be a file name pattern of the same type
that you can specify in the .cvswrappers
file. See Wrappers.
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 modules.)
See Tracking sources, and From 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 Common options).
By default, log prints all information that is
available. All other options restrict the output.
-b
-d dates
-D option to
many other CVS commands (see Common options).
Dates can be combined into ranges as follows:
d1<d2
d2>d1
<d
d>
d<
>d
d
The > or < characters may be followed by
= to indicate an inclusive range rather than an
exclusive one.
Note that the separator is a semicolon (;).
-h
-l
-N
-R
-rrevisions
rev1:rev2
:rev
rev:
branch
branch1:branch2
branch.
A bare -r with no revisions means the latest
revision on the default branch, normally the trunk.
There can be no space between the -r option and
its argument.
-s states
-t
-h, plus the descriptive text.
-wlogins
-w option and its argument.
log prints the intersection of the revisions
selected with the options -d, -s, and
-w, intersected with the union of the revisions
selected by -b and -r.
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 Common 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 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
Warning: The 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 Adding files) 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 Adding files) will be
silently ignored (and deleted, if -d is
specified), even if they contain files.
U file
P file
U and P mean the same thing).
A file
R file
M file
? file
-I option, and
see cvsignore). If you remove your working
sources, this file will be lost.
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 tag), to base the
selection of revisions on the contents of your
working directory.
If you attempt to use a tag name that already exists,
CVS will complain and not overwrite that tag. Use
the -F option to force the new tag value.
These standard options are supported by rtag
(see Common options, for a complete description of
them):
-D date
-f
-D date or -r tag
flags. If no matching revision is found, use the most
recent revision (instead of ignoring the file).
-F
-l
-n
-t flag inside the modules file.
(see modules).
-R
-r tag
In addition to the above common options, these options are available:
-a
-a option to have rtag look in the
Attic (see 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
In general, tags (often the symbolic names of software
distributions) should not be removed, but the -d
option is available as a means to remove completely
obsolete symbolic names if necessary (as might be the
case for an Alpha release, or if you mistagged a
module).
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 Common options, for a complete description of
them):
-F
-l
-R
Two special options are available:
-b
-c
-d
If you use cvs tag -d symbolic_tag, the symbolic
tag you specify is deleted instead of being added.
Warning: Be very certain of your ground before you
delete a tag; doing this permanently discards some
historical information, which may later turn out to
be valuable.
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 Common options, for a complete description of
them):
-D date
-P.
See Sticky tags, for more information on sticky tags/dates.
-f
-D date or -r
tag flags. If no matching revision is found,
retrieve the most recent revision (instead of ignoring
the file).
-k kflag
status command can be viewed
to see the sticky options. See Invoking CVS, for
more information on the status command.
-l
-P
-p
-R
-r rev
-P.
See Sticky tags, for more information on sticky tags/dates.
These special options are also available with
update.
-A
-k options.
See Sticky tags, for more information on sticky tags/dates.
-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
-I more than once on the command line to specify
several files to ignore. Use -I ! to avoid
ignoring any files at all. See cvsignore, for other
ways to make CVS ignore some files.
-Wspec
spec can be a file name pattern of the same type
that you can specify in the .cvswrappers
file. See Wrappers.
-jrevision
-j options, merge changes from the
revision specified with the first -j option to
the revision specified with the second j option,
into the working directory.
With one -j option, merge changes from the
ancestor revision to the revision specified with the
-j option, into the working directory. The
ancestor revision is the common ancestor of the
revision which the working directory is based on, and
the revision specified in the -j option.
In addition, each -j option can contain an optional
date specification which, when used with branches, can
limit the chosen revision to one within a specific
date. An optional date is specified by adding a colon
(:) to the tag:
-jSymbolic_Tag:Date_Specifier.
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
U, but the CVS server sends a patch
instead of an entire file. These two things accomplish
the same thing.
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
M can indicate one of two states for a file
you're working on: either there were no modifications
to the same file in the repository, so that your file
remains as you last saw it; or there were modifications
in the repository as well as in your copy, but they
were merged successfully, without conflict, in your
working directory.
CVS will print some messages if it merges your work,
and a backup copy of your working file (as it looked
before you ran update) will be made. The exact
name of that file is printed while update runs.
C file
.#file.revision where revision
is the revision that your modified file started
from. Resolve the conflict as described in
Conflicts example.
(Note that some systems automatically purge
files that begin with .# if they have not been
accessed for a few days. If you intend to keep a copy
of your original file, it is a very good idea to rename
it.) Under VMS, the file name starts with
__ rather than .#.
? file
-I option, and
see cvsignore).
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 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
~/.cvsrc file. See Global options.
-H
--help
-l
-n
-Q
-q
-r
-s variable=value
-T tempdir
-t
-v
--version
-w
-x
-z gzip-level
Keyword expansion modes (see 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 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...]
-c for context diffs.
-D date1
-D date2
-l
-N
-R
-r rev1
-r rev2
edit [options] [files...]
-a actions
edit, unedit,
commit, all, or none. See
Editing files.
-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 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
Editing files.
-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...]
add/remove: add or remove notification on actions. See Getting Notified.
-a actions
edit, unedit,
commit, all, or none. See
Editing files.
-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 Intro 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...
-a flags the definition as a
simple alias: CVS will treat any use of mname (as
a command argument) as if the list of names
aliases had been specified instead.
aliases may contain either other module names or
paths. When you use paths in aliases, checkout
creates all intermediate directories in the working
directory, just as if the path had been specified
explicitly in the CVS arguments.
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... ]
mname dir. This defines
all the files in directory dir as module mname.
dir is a relative path (from $CVSROOT) to a
directory of source in the source repository. In this
case, on checkout, a single directory called
mname is created as a working directory; no
intermediate directory levels are used by default, even
if dir was a path involving several directory
levels.
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
commitinfo,
loginfo, and verifymsg files provide other
ways to call a program on commit.
-o prog
-s status
cvs checkout -s the modules are
sorted according to primarily module status, and
secondarily according to the module name. This option
has no other meaning. You can use this option for
several things besides status: for instance, list the
person that is responsible for this module.
-t prog
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 user-defined logging).
-u prog
cvs
update is executed from the top-level directory of the
checked-out module. prog runs with a single
argument, the full path to the source repository for
this module.
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 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 users 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 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 modules). The files described in
this section provide other, more flexible, ways to run
programs whenever something is committed.
There are three kind of programs that can be run on commit. They are specified in files in the repository, as described below. The following table summarizes the file names and the purpose of the corresponding programs.
commitinfo
verifymsg
rcsinfo file, which can hold a log message
template (see rcsinfo).
editinfo
rcsinfo file, which can hold a log message
template (see rcsinfo). (obsolete)
loginfo
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 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 Environment variables) or the -e global
option (see Global options). See verifymsg,
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 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 commit 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 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) &) >> $CVSROOT/CVSROOT/updatelog 2>&1
This will cause checkins to repository directories
starting with cyclic-pages to update the checked
out tree in /u/www/local-docs.
The rcsinfo file can be used to specify a form to
edit when filling out the commit log. The
rcsinfo file has a syntax similar to the
verifymsg, commitinfo and loginfo
files. See syntax. Unlike the other files the second
part is not a command-line template. Instead,
the part after the regular expression should be a full pathname to
a file containing the log message template.
If the repository name does not match any of the
regular expressions in this file, the DEFAULT
line is used, if it is specified.
All occurances of the name ALL appearing as a
regular expression are used in addition to the first
matching regular expression or DEFAULT.
The log message template will be used as a default log
message. If you specify a log message with cvs
commit -m message or cvs commit -f
file that log message will override the
template.
See verifymsg, for an example rcsinfo
file.
When CVS is accessing a remote repository,
the contents of rcsinfo at the time a directory
is first checked out will specify a template which does
not then change. If you edit rcsinfo or its
templates, you may need to check out a new working
directory.
There are certain file names that frequently occur
inside your working copy, but that you don't want to
put under CVS control. Examples are all the object
files that you get while you compile your sources.
Normally, when you run cvs update, it prints a
line for each file it encounters that it doesn't know
about (see update output).
CVS has a list of files (or sh(1) file name patterns)
that it should ignore while running update,
import and release.
This list is constructed in the following way.
RCS SCCS CVS CVS.adm
RCSLOG cvslog.*
tags TAGS
.make.state .nse_depinfo
*~ #* .#* ,* _$* *$
*.old *.bak *.BAK *.orig *.rej .del-*
*.a *.olb *.o *.obj *.so *.exe
*.Z *.elc *.ln
core
$CVSROOT/CVSROOT/cvsignore is appended to
the list, if that file exists.
.cvsignore in your home
directory is appended to the list, if it exists.
$CVSIGNORE is appended to the list.
-I options given to CVS is appended.
.cvsignore will be appended to the list.
The patterns found in .cvsignore are only valid
for the directory that contains them, not for
any sub-directories.
In any of the 5 places listed above, a single
exclamation mark (!) clears the ignore list.
This can be used if you want to store any file which
normally is ignored by CVS.
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 history). This file must be created to turn
on logging. This is done automatically if the
cvs init command is used to set up the
repository (see Creating a repository).
The file format of the history file is
documented only in comments in the CVS source
code, but generally programs should use the cvs
history command to access it anyway, in case the
format changes with future releases of CVS.
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 Password authenticated)
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 ~/.cvsrc).
For example, if you want the administrative file to
refer to a test directory you might create a user
variable TESTDIR. Then if CVS is invoked
as
cvs -s TESTDIR=/work/local/tests
and the
administrative file contains sh
${=TESTDIR}/runtests, then that string is expanded
to sh /work/local/tests/runtests.
All other strings containing $ are reserved;
there is no way to quote a $ character so that
$ represents itself.
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
yes, then pserver should check
for users in the system's user database if not found in
CVSROOT/passwd. If it is no, then all
pserver users must exist in CVSROOT/passwd.
The default is yes. For more on pserver, see
Password authenticated.
PreservePermissions=value
no.
See Special Files for the full implications of using
this keyword.
TopLevelAdmin=value
checkout command to create a
CVS directory at the top level of the new
working directory, in addition to CVS
directories created within checked-out directories.
The default value is no.
This option is useful if you find yourself performing
many commands at the top level of your working
directory, rather than in one of the checked out
subdirectories. The CVS directory created there
will mean you don't have to specify CVSROOT for
each command. It also provides a place for the
CVS/Template file (see Working directory storage).
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 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
.cvsrc
file, and other such files, are searched. On Unix, CVS
just checks for HOME. On Windows NT, the system will
set HOMEDRIVE, for example to d: and HOMEPATH,
for example to \joe. On Windows 95, you'll
probably need to set HOMEDRIVE and HOMEPATH yourself.
$CVS_RSH
:ext: access method is specified.
see Connecting via rsh.
$CVS_SERVER
cvs. see Connecting via rsh
$CVS_PASSFILE
cvs
login server. Default value is $HOME/.cvspass.
see Password authentication client
$CVS_CLIENT_PORT
$CVS_RCMD_PORT
$CVS_CLIENT_LOG
$CVS_CLIENT_LOG.in$CVS_CLIENT_LOG.out$CVS_SERVER_SLEEP
$CVS_IGNORE_REMOTE_ROOT
$COMSPEC
$TMPDIR
$TMP
$TEMP
TMPDIR. See 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 Watches Compatibility, 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
cvs add file. If desired, look
at the other party's modification to decide whether you
still want to remove it. If you don't want to remove
it, stop here. If you do want to remove it, proceed
with cvs remove file and commit your
removal.
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 BUGS. 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 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 BUGS).
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
-t global option. It
was fixed by Andy Piper's 14 Nov 1997 change to
src/filesubr.c, if anyone is curious.
If you see the message,
you probably can just retry the operation which failed,
or if you have discovered information concerning its
cause, please let us know as described in BUGS.
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 Remote repositories.
cvs commit: Executing 'mkmodules'
cvs commit: Rebuilding administrative file database
If 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 modules.
missing author
*PANIC* administration files missing
rcs error: Unknown option: -x,v/
cvs [server aborted]: received broken pipe signal
Too many arguments!
log.pl
script which is in the contrib directory in the
CVS source distribution. In some versions of
CVS, log.pl has been part of the default
CVS installation. The log.pl script gets
called from the loginfo administrative file.
Check that the arguments passed in loginfo match
what your version of log.pl expects. In
particular, the log.pl from CVS 1.3 and
older expects the logfile as an argument whereas the
log.pl from CVS 1.5 and newer expects the
logfile to be specified with a -f option. Of
course, if you don't need log.pl you can just
comment it out of loginfo.
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
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
ok) followed by an extra carriage return
character (on many systems this will cause the second
part of the message to overwrite the first part), then
it probably means that you are using the :ext:
access method with a version of rsh, such as most
non-unix rsh versions, which does not by default
provide a transparent data stream. In such cases you
probably want to try :server: instead of
:ext:. If text is something else, this
may signify a problem with your CVS server.
Double-check your installation against the instructions
for setting up the 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: foo
If 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 hello
After 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 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.html
If 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.