Author: Written by Marc G. Fournier (<scrappy@hub.org>) on 1998-11-05
The command cvs checkout has a flag, -r, that lets you check out a certain revision of a module. This flag makes it easy to, for example, retrieve the sources that make up release 6_4 of the module `tc' at any time in the future:
$ cvs checkout -r REL6_4 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.
Tip: You can also check out a module as it was at any given date using the -D option.
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
then the tag TAG will reference file1-1.2, file2-1.3, etc.
Note: For creating a release branch, other then a -b option added to the command, it's the same thing.
So, to create the 6.4 release I did the following:
$ cd pgsql $ cvs tag -b REL6_4
which will create the tag and the branch for the RELEASE tree.
For those with CVS access, it's simple to create directories for different versions. First, create two subdirectories, RELEASE and CURRENT, so that you don't mix up the two. Then do:
cd RELEASE cvs checkout -P -r REL6_4 pgsql cd ../CURRENT cvs checkout -P pgsql
which results in two directory trees, RELEASE/pgsql and CURRENT/pgsql. From that point on, CVS will keep track of which repository branch is in which directory tree, and will allow independent updates of either tree.
If you are only working on the CURRENT source tree, you just do everything as before we started tagging release branches.
After you've done the initial checkout on a branch
$ cvs checkout -r REL6_4
anything you do within that directory structure is restricted to that branch. If you apply a patch to that directory structure and do a
cvs commit
while inside of it, the patch is applied to the branch and only the branch.