This is cvs.info, produced by makeinfo version 4.0b from cvs.texinfo.

START-INFO-DIR-ENTRY
* CVS: (cvs).          Concurrent Versions System
END-INFO-DIR-ENTRY

   Copyright (C) 1992, 1993 Signum Support AB Copyright (C) 1993, 1994
Free Software Foundation, Inc.

   Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

   Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided also
that the entire resulting derived work is distributed under the terms
of a permission notice identical to this one.

   Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that this permission notice may be stated in a
translation approved by the Free Software Foundation.


File: cvs.info,  Node: Tags,  Next: Tagging the working directory,  Prev: Assigning revisions,  Up: Revisions

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

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

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

   You can use the `tag' command to give a symbolic name to a certain
revision of a file.  You can use the `-v' flag to the `status' command
to see all tags that a file has, and which revision numbers they
represent.  Tag names 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 (*note user-defined
logging::).

   The following example shows how you can add a tag to a file.  The
commands must be issued inside your working directory.  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)

   For a complete summary of the syntax of `cvs tag', including the
various options, see *Note Invoking CVS::.

   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.  *Note 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.  *Note
checkout options::.  When specifying `-r' to any of these commands, you
will need beware of sticky tags; see *Note Sticky tags::.

   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


File: cvs.info,  Node: Tagging the working directory,  Next: Tagging by date/tag,  Prev: Tags,  Up: Revisions

Specifying what to tag from the working directory
=================================================

   The example in the previous section demonstrates one of the most
common ways to choose which revisions to tag.  Namely, running the `cvs
tag' command without arguments causes CVS to select the revisions which
are checked out in the current working directory.  For example, if the
copy of `backend.c' in working directory was checked out from revision
1.4, then CVS will tag revision 1.4.  Note that the tag is applied
immediately to revision 1.4 in the repository; tagging is not like
modifying a file, or other operations in which one first modifies the
working directory and then runs `cvs commit' to transfer that
modification to the repository.

   One potentially surprising aspect of the fact that `cvs tag'
operates on the repository is that you are tagging the checked-in
revisions, which may differ from locally modified files in your working
directory.  If you want to avoid doing this by mistake, specify the
`-c' option to `cvs tag'.  If there are any locally modified files, CVS
will abort with an error before it tags any files:

     $ cvs tag -c rel-0-4
     cvs tag: backend.c is locally modified
     cvs [tag aborted]: correct the above errors first!


File: cvs.info,  Node: Tagging by date/tag,  Next: Modifying tags,  Prev: Tagging the working directory,  Up: Revisions

Specifying what to tag by date or revision
==========================================

   The `cvs rtag' command tags the repository as of a certain date or
time (or can be used to tag the latest revision).  `rtag' works
directly on the repository contents (it requires no prior checkout and
does not look for a working directory).

   The following options specify which date or revision to tag.  See
*Note Common options::, for a complete description of them.

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

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

`-r TAG'
     Only tag those files that contain existing tag TAG.

   The `cvs tag' command also allows one to specify files by revision
or date, using the same `-r', `-D', and `-f' options.  However, this
feature is probably not what you want.  The reason is that `cvs tag'
chooses which files to tag based on the files that exist in the working
directory, rather than the files which existed as of the given tag/date.
Therefore, you are generally better off using `cvs rtag'.  The
exceptions might be cases like:

     cvs tag -r 1.4 backend.c


File: cvs.info,  Node: Modifying tags,  Next: Tagging add/remove,  Prev: Tagging by date/tag,  Up: Revisions

Deleting, moving, and renaming tags
===================================

   Normally one does not modify tags.  They exist in order to record
the history of the repository and so deleting them or changing their
meaning would, generally, not be what you want.

   However, there might be cases in which one uses a tag temporarily or
accidentally puts one in the wrong place.  Therefore, one might delete,
move, or rename a tag.

_Warning: the commands in this section are dangerous; they permanently
discard historical information and it can be difficult or impossible to
recover from errors.  If you are a CVS administrator, you may consider
restricting these commands with taginfo (*note user-defined logging::)._

   To delete a tag, specify the `-d' option to either `cvs tag' or `cvs
rtag'.  For example:

     cvs rtag -d rel-0-4 tc

deletes the non-branch tag `rel-0-4' from the module `tc'.  In the
event that branch tags are encountered within the repository with the
given name, a warning message will be issued and the branch tag will
not be deleted.  If you are absolutely certain you know what you are
doing, the `-B' option may be specified to allow deletion of branch
tags.  In that case, any non-branch tags encountered will trigger
warnings and will not be deleted.

_Warning: Moving branch tags is very dangerous!  If you think you need
the `-B' option, think again and ask your CVS administrator about it (if
that isn't you).  There is almost certainly another way to accomplish
what you want to accomplish._

   When we say "move" a tag, we mean to make the same name point to
different revisions.  For example, the `stable' tag may currently point
to revision 1.4 of `backend.c' and perhaps we want to make it point to
revision 1.6.  To move a non-branch tag, specify the `-F' option to
either `cvs tag' or `cvs rtag'.  For example, the task just mentioned
might be accomplished as:

     cvs tag -r 1.6 -F stable backend.c

If any branch tags are encountered in the repository with the given
name, a warning is issued and the branch tag is not disturbed.  If you
are absolutely certain you wish to move the branch tag, the `-B' option
may be specified.  In that case, non-branch tags encountered with the
given name are ignored with a warning message.

_Warning: Moving branch tags is very dangerous!  If you think you need
the `-B' option, think again and ask your CVS administrator about it (if
that isn't you).  There is almost certainly another way to accomplish
what you want to accomplish._

   When we say "rename" a tag, we mean to make a different name point
to the same revisions as the old tag.  For example, one may have
misspelled the tag name and want to correct it (hopefully before others
are relying on the old spelling).  To rename a tag, first create a new
tag using the `-r' option to `cvs rtag', and then delete the old name.
(Caution: this method will not work with branch tags.)  This leaves the
new tag on exactly the same files as the old tag.  For example:

     cvs rtag -r old-name-0-4 rel-0-4 tc
     cvs rtag -d old-name-0-4 tc


File: cvs.info,  Node: Tagging add/remove,  Next: Sticky tags,  Prev: Modifying tags,  Up: Revisions

Tagging and adding and removing files
=====================================

   The subject of exactly how tagging interacts with adding and
removing files is somewhat obscure; for the most part CVS will keep
track of whether files exist or not without too much fussing.  By
default, tags are applied to only files which have a revision
corresponding to what is being tagged.  Files which did not exist yet,
or which were already removed, simply omit the tag, and CVS knows to
treat the absence of a tag as meaning that the file didn't exist as of
that tag.

   However, this can lose a small amount of information.  For example,
suppose a file was added and then removed.  Then, if the tag is missing
for that file, there is no way to know whether the tag refers to the
time before the file was added, or the time after it was removed.  If
you specify the `-r' option to `cvs rtag', then CVS tags the files
which have been removed, and thereby avoids this problem.  For example,
one might specify `-r HEAD' to tag the head.

   On the subject of adding and removing files, the `cvs rtag' command
has a `-a' option which means to clear the tag from removed files that
would not otherwise be tagged.  For example, one might specify this
option in conjunction with `-F' when moving a tag.  If one moved a tag
without `-a', then the tag in the removed files might still refer to
the old revision, rather than reflecting the fact that the file had
been removed.  I don't think this is necessary if `-r' is specified, as
noted above.


File: cvs.info,  Node: Sticky tags,  Prev: Tagging add/remove,  Up: Revisions

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

   Sometimes a working copy's revision has extra data associated with
it, for example it might be on a branch (*note 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 *Note 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.

   People often want to retrieve an old version of a file without
setting a sticky tag.  This can be done with the `-p' option to
`checkout' or `update', which sends the contents of the file to
standard output.  For example:
     $ cvs update -p -r 1.1 file1 >file1
     ===================================================================
     Checking out file1
     RCS:  /tmp/cvs-sanity/cvsroot/first-dir/Attic/file1,v
     VERS: 1.1
     ***************
     $

   However, this isn't the easiest way, if you are asking how to undo a
previous checkin (in this example, put `file1' back to the way it was
as of revision 1.1).  In that case you are better off using the `-j'
option to `update'; for further discussion see *Note Merging two
revisions::.


File: cvs.info,  Node: Branching and merging,  Next: Recursive behavior,  Prev: Revisions,  Up: Top

Branching and merging
*********************

   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.

* Menu:

* Branches motivation::         What branches are good for
* Creating a branch::           Creating a branch
* Accessing branches::          Checking out and updating branches
* Branches and revisions::      Branches are reflected in revision numbers
* Magic branch numbers::        Magic branch numbers
* Merging a branch::            Merging an entire branch
* Merging more than once::      Merging from a branch several times
* Merging two revisions::       Merging differences between two revisions
* Merging adds and removals::   What if files are added or removed?
* Merging and keywords::        Avoiding conflicts due to keyword substitution


File: cvs.info,  Node: Branches motivation,  Next: Creating a branch,  Up: Branching and merging

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

   Suppose that release 1.0 of tc has been made.  You are continuing to
develop tc, planning to create release 1.1 in a couple of months.
After a while your customers start to complain about a fatal bug.  You
check out release 1.0 (*note 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.


File: cvs.info,  Node: Creating a branch,  Next: Accessing branches,  Prev: Branches motivation,  Up: Branching and merging

Creating a 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 *Note 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'.


File: cvs.info,  Node: Accessing branches,  Next: Branches and revisions,  Prev: Creating a branch,  Up: Branching and merging

Accessing branches
==================

   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 (*note 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'
(*note 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 *Note Branches and revisions:: for details about how branch
numbers are constructed.


File: cvs.info,  Node: Branches and revisions,  Next: Magic branch numbers,  Prev: Accessing branches,  Up: Branching and merging

Branches and revisions
======================

   Ordinarily, a file's revision history is a linear series of
increments (*note 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 (*note Magic branch
numbers::).  The branch 1.1.1 has a special meaning.  *Note Tracking
sources::.


File: cvs.info,  Node: Magic branch numbers,  Next: Merging a branch,  Prev: Branches and revisions,  Up: Branching and merging

Magic branch numbers
====================

   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.  *Note 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:

   * The magic branch number appears in the output from `cvs log'.

   * You cannot specify a symbolic branch name to `cvs admin'.


   You can use the `admin' command to reassign a symbolic name to a
branch the way RCS expects it to be.  If `R4patches' is assigned to the
branch 1.4.2 (magic branch number 1.4.0.2) in file `numbers.c' you can
do this:

     $ cvs admin -NR4patches:1.4.2 numbers.c

   It only works if at least one revision is already committed on the
branch.  Be very careful so that you do not assign the tag to the wrong
number.  (There is no way to see how the tag was assigned yesterday).


File: cvs.info,  Node: Merging a branch,  Next: Merging more than once,  Prev: Magic branch numbers,  Up: Branching and merging

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

   You can merge changes made on a branch into your working copy by
giving the `-j BRANCHNAME' flag to the `update' subcommand.  With one
`-j BRANCHNAME' 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.  *Note Conflicts
example::.

   If your source files contain keywords (*note Keyword substitution::),
you might be getting more conflicts than strictly necessary.  See *Note
Merging and keywords::, for information on how to avoid this.

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

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

   It should be noted that `update -j TAGNAME' will also work but may
not produce the desired result.  *Note Merging adds and removals::, for
more.


File: cvs.info,  Node: Merging more than once,  Next: Merging two revisions,  Prev: Merging a branch,  Up: Branching and merging

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

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

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

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

   Now suppose that development continues on the `R1fix' branch:

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

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

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

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

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

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

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

     cvs update -j merged_from_R1fix_to_trunk -j R1fix m.c


File: cvs.info,  Node: Merging two revisions,  Next: Merging adds and removals,  Prev: Merging more than once,  Up: Branching and merging

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

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

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

will undo 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.  You almost always use symbolic tags rather
than revision numbers when operating on multiple files.

   Specifying two `-j' options can also undo file removals or
additions.  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 -j 1.2 -j 1.1 file1
     U file1
     $ 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
     $


File: cvs.info,  Node: Merging adds and removals,  Next: Merging and keywords,  Prev: Merging two revisions,  Up: Branching and merging

Merging can add or remove 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.

   Note that using a single static tag (`-j TAGNAME') rather than a
dynamic tag (`-j BRANCHNAME') to merge changes from a branch will
usually not remove files which were removed on the branch since CVS
does not automatically add static tags to dead revisions.  The
exception to this rule occurs when a static tag has been attached to a
dead revision manually.  Use the branch tag to merge all changes from
the branch or use two static tags as merge endpoints to be sure that
all intended changes are propogated in the merge.


File: cvs.info,  Node: Merging and keywords,  Prev: Merging adds and removals,  Up: Branching and merging

Merging and keywords
====================

   If you merge files containing keywords (*note Keyword
substitution::), you will normally get numerous conflicts during the
merge, because the keywords are expanded differently in the revisions
which you are merging.

   Therefore, you will often want to specify the `-kk' (*note
Substitution modes::) switch to the merge command line.  By
substituting just the name of the keyword, not the expanded value of
that keyword, this option ensures that the revisions which you are
merging will be the same as each other, and avoid spurious conflicts.

   For example, suppose you have a file like this:

            +---------+
           _! 1.1.2.1 !   <-  br1
          / +---------+
         /
        /
     +-----+    +-----+
     ! 1.1 !----! 1.2 !
     +-----+    +-----+

and your working directory is currently on the trunk (revision 1.2).
Then you might get the following results from a merge:

     $ cat file1
     key $Revision: 1.2 $
     . . .
     $ cvs update -j br1
     U file1
     RCS file: /cvsroot/first-dir/file1,v
     retrieving revision 1.1
     retrieving revision 1.1.2.1
     Merging differences between 1.1 and 1.1.2.1 into file1
     rcsmerge: warning: conflicts during merge
     $ cat file1
     <<<<<<< file1
     key $Revision: 1.2 $
     =======
     key $Revision: 1.1.2.1 $
     >>>>>>> 1.1.2.1
     . . .

   What happened was that the merge tried to merge the differences
between 1.1 and 1.1.2.1 into your working directory.  So, since the
keyword changed from `Revision: 1.1' to `Revision: 1.1.2.1', CVS tried
to merge that change into your working directory, which conflicted with
the fact that your working directory had contained `Revision: 1.2'.

   Here is what happens if you had used `-kk':

     $ cat file1
     key $Revision: 1.2 $
     . . .
     $ cvs update -kk -j br1
     U file1
     RCS file: /cvsroot/first-dir/file1,v
     retrieving revision 1.1
     retrieving revision 1.1.2.1
     Merging differences between 1.1 and 1.1.2.1 into file1
     $ cat file1
     key $Revision$
     . . .

   What is going on here is that revision 1.1 and 1.1.2.1 both expand
as plain `Revision', and therefore merging the changes between them
into the working directory need not change anything.  Therefore, there
is no conflict.

   There is, however, one major caveat with using `-kk' on merges.
Namely, it overrides whatever keyword expansion mode CVS would normally
have used.  In particular, this is a problem if the mode had been `-kb'
for a binary file.  Therefore, if your repository contains binary
files, you will need to deal with the conflicts rather than using `-kk'.


File: cvs.info,  Node: Recursive behavior,  Next: Adding and removing,  Prev: Branching and merging,  Up: Top

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

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

           `$HOME'
             |
             +--tc
             |   |
                 +--CVS
                 |      (internal CVS files)
                 +--Makefile
                 +--backend.c
                 +--driver.c
                 +--frontend.c
                 +--parser.c
                 +--man
                 |    |
                 |    +--CVS
                 |    |  (internal CVS files)
                 |    +--tc.1
                 |
                 +--testing
                      |
                      +--CVS
                      |  (internal CVS files)
                      +--testpgm.t
                      +--test2.t

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

   * `cvs update testing' is equivalent to

          cvs update testing/testpgm.t testing/test2.t

   * `cvs update testing man' updates all files in the subdirectories

   * `cvs update .' or just `cvs update' updates all files in the `tc'
     directory

   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' (*note ~/.cvsrc::).

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


File: cvs.info,  Node: Adding and removing,  Next: History browsing,  Prev: Recursive behavior,  Up: Top

Adding, removing, and renaming files and directories
****************************************************

   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.

* Menu:

* Adding files::                Adding files
* Removing files::              Removing files
* Removing directories::        Removing directories
* Moving files::                Moving and renaming files
* Moving directories::          Moving and renaming directories


File: cvs.info,  Node: Adding files,  Next: Removing files,  Up: Adding and removing

Adding files to a directory
===========================

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

   * You must have a working copy of the directory.  *Note Getting the
     source::.

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

   * Use `cvs add FILENAME' to tell CVS that you want to version
     control the file.  If the file contains binary data, specify `-kb'
     (*note Binary files::).

   * Use `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

 - Command: cvs add [`-k' kflag] [`-m' message] files ...
     Schedule FILES to be added to the repository.  The files or
     directories specified with `add' must already exist in the current
     directory.  To add a whole new directory hierarchy to the source
     repository (for example, files received from a third-party
     vendor), use the `import' command instead.  *Note import::.

     The added files are not placed in the source repository until you
     use `commit' to make the change permanent.  Doing an `add' on a
     file that was removed with the `remove' command will undo the
     effect of the `remove', unless a `commit' command intervened.
     *Note Removing files::, for an example.

     The `-k' option specifies the default way that this file will be
     checked out; for more information see *Note Substitution modes::.

     The `-m' option specifies a description for the file.  This
     description appears in the history log (if it is enabled, *note
     history file::).  It will also be saved in the version history
     inside the repository when the file is committed.  The `log'
     command displays this description.  The description can be changed
     using `admin -t'.  *Note admin::.  If you omit the `-m
     DESCRIPTION' flag, an empty string will be used.  You will not be
     prompted for a description.

   For example, the following commands add the file `backend.c' to the
repository:

     $ cvs add backend.c
     $ cvs commit -m "Early version. Not yet compilable." backend.c

   When you add a file it is added only on the branch which you are
working on (*note Branching and merging::).  You can later merge the
additions to another branch if you want (*note Merging adds and
removals::).


File: cvs.info,  Node: Removing files,  Next: Removing directories,  Prev: Adding files,  Up: Adding and removing

Removing files
==============

   Directories 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:

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

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

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

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

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

 - Command: cvs remove [options] files ...
     Schedule file(s) to be removed from the repository (files which
     have not already been removed from the working directory are not
     processed).  This command does not actually remove the file from
     the repository until you commit the removal.  For a full list of
     options, see *Note 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 (*note Branching and merging::).  You can later merge
the removals to another branch if you want (*note Merging adds and
removals::).


File: cvs.info,  Node: Removing directories,  Next: Moving files,  Prev: Removing files,  Up: Adding and removing

Removing directories
====================

   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' or `cvs checkout',
which will cause CVS to remove empty directories from working
directories.  (Note that `cvs export' always removes empty 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'.
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.


File: cvs.info,  Node: Moving files,  Next: Moving directories,  Prev: Removing directories,  Up: Adding and removing

Moving and renaming files
=========================

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

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

* Menu:

* Outside::                     The normal way to Rename
* Inside::                      A tricky, alternative way
* Rename by copying::           Another tricky, alternative way


File: cvs.info,  Node: Outside,  Next: Inside,  Up: Moving files

The Normal way to Rename
------------------------

   The normal way to move a file is to copy OLD to NEW, and then issue
the normal CVS commands to remove OLD from the repository, and add NEW
to it.

     $ 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 *Note Assigning revisions::.


File: cvs.info,  Node: Inside,  Next: Rename by copying,  Prev: Outside,  Up: Moving files

Moving the history file
-----------------------

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

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

Advantages:

   * The log of changes is maintained intact.

   * The revision numbers are not affected.

Disadvantages:

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

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

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

