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(cvs.info)Tags

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Tags-Symbolic revisions
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   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