How Can I Use CVS?
CVS is your friend. CVS is a great tool for maintaining source
code. Using CVS, you can keep track of changes you've made and revert back to
a previous version of the code, if needed.
CVSWeb is a good friend of CVS.
Importing Source into the Repository
- Make sure that the files you are including are only source files.
Importing binary files is special (see CVS FAQ for more
- Change directory to the source that you want to import.
- Choose a MODULE (directory under the root repository), VENDOR_TAG (to
identify this code -- no spaces or dashes), and RELEASE_TAG (to identify the
version of this code -- no spaces or dashes).
- % cvs import -m "MESSAGE" MODULE VENDOR_TAG RELEASE_TAG
example: [~clark/ns/ns-2.1b7a]% cvs import -m "ns-2.1b7a" ns-2 NS
Checking Out Code from the Repository
- Change directory to where you want the directory created.
- % cvs checkout [-r REV] [-d DIR] MODULE
example: [~clark/src]% cvs checkout -r HEAD -d ns-2.1b7a ns-2
This example would checkout the head of the ns-2 module (latest revisions) to the directory ~clark/src/ns-2.1b7a/. This is called the
working directory. If "-d ns-2.1b7a" hadn't been included, the source
would have been checked-out to ~clark/src/ns-2/.
You can also checkout a version based on the date and time. Use the -D option followed by the date.
Example: -D "2001-09-04 21:00" One oddity is that
the date you specify is 4 hours earlier than the date of the commit that is
checked out (at least for me).
More Examples: -D "yesterday", -D "tomorrow", -D "12 days ago"
Committing Changes to the Repository
- Change directory to your working directory.
- % cvs commit
example: [~clark/src/ns-2.1b7a]% cvs commit
- If others had been working on the same code, you might have to resolve
conflicts. But, that's not really our model of working (yet), so we don't have
to worry about it (yet).
Tagging a Group of Changes
Tagging lets you group files to create a snapsnot of a certain point in time.
You can then checkout files based on this tag (by using the tag name in place
of the revision).
- Commit the changes.
- % cvs tag TAG_NAME
example: [~clark/src/ns-2.1b7a]% cvs tag RSPTIME_1_0
Merging in a New Vendor Release
First, read up on the process. Useful links:
The basic idea is to import the new vendor source into the vendor
branch and do a three-way merge (diff of original source and new vendor source
get merged into your changed code).
Here's what I did to merge in ns-2-snapshot-20010903 into my modified source (ns-packmime), which was based on ns-2.1b8:
- Commit latest version of modifications:
[~/ns-allinone/ns-packmime]% cvs commit
- Tag latest version of modifications:
[~/ns-allinone/ns-packmime]% cvs tag NS_2_1B8_PACKMIME
- Release latest version of modifications:
[~/ns-allinone]% cvs release -d ns-packmime
- Unpack ns-2 snapshot:
[~/ns-allinone]% tar xzvf ns-snapshot.tar.gz
- Import the snapshot into the vendor branch (module name = ns, vendor tag = NS, release tag = NS_2_SNAPSHOT_20010903):
[~/ns-allinone/ns-2-snapshot]% cvs import -m "ns-2-snapshot-20010903" ns NS NS_2_SNAPSHOT_20010903 >& import.log
- Check out the latest revision of ns and merge the changes made since the
vendor releases into the working copy:
[~/ns-allinone]% cvs checkout -jNS_2_1B8 -jNS_2_SNAPSHOT_20010903 ns >& checkout.log
- Look for conflicts and manually fix:
[~/ns-allinone/ns]% grep -r "<<<" *
- Build and test. Commit changes.
[~/ns-allinone/ns]% cvs commit
CVS makes it really easy to create a patch from one revision to another. I wanted a patch from ns-2.1b8 to my current changes, I wrote create-patch.csh. To apply these patches, I used patch.pl.
Here's what I did before (the new scripts are WAY easier!):
[~clark/src/ns-2.1b8]% cvs commit
[~clark/src/ns-2.1b8]% cd ..
[~clark/src]% cvs patch -kk -R -r NS_2_1B8 -D now ns-2 > packmime.patch
- "-kk" ignores the Header: comments at the beginning of each file
- "-R" recurses through the entire tree
- "-r NS_2_1B8" looks at the import tagged NS_2_1B8
- "-D now" compares the import against the latest commit
One problem I had was that the patch didn't work in directories below
ns-2.1b8. So, I cut apart packmime.patch and created a patch file for each
directory that needed patching. (This is also why I created the script
to make the patch.)
- cvs diff - compares the working directory against the current repository
- cvs update FILES - merges changes to the repository into your working
directory, is most useful to us as a method of retrieving previous versions of
example: [~clark/src/ns-2.1b7a]% cvs update -p -r 1.1 Makefile >
- "-p" sends the file to STDOUT
- "-r REV" indicates which version of the file to retrieve
- cvs add FILES - add the files to the repository on the next commit
- Copy the contents of ~clark/public_html/cvsweb (AFS-land) into your
(or grab the latest source)
- Read INSTALL
- Edit cvsweb.conf so that it points to your CVSROOT and displays a
web page title you'd prefer
- Copy ~clark/public_html/cgi-bin/cvsweb.cgi (AFS-land) to your
- Give all users read/write/execute permissions to your CVSROOT and
- The location of your cvsweb interface should be
http://wwwx.cs.unc.edu/~yourusername/cgi-bin/cvsweb.cgi (Note: You
must use wwwx)
Author: Michele Weigle