How to CVS

I know… I know… CVS? Really? Yes, really. Some venerable projects still swear by it, and if you find yourself here, congratulations — you are about to pilot a vintage time machine of version control. Think of it as a classic car: a bit old-school, occasionally cranky, but if you know what you’re doing, it still gets you where you need to go.

Some documentation

Configuration

Setting up the environment

Before CVS can take off, you need to tell your shell where the repository lives:

$ CVSROOT=/path/to/cvsroot
$ export CVSROOT

Replace /path/to/cvsroot with the actual path or remote location.: Pro tip: put this in your .bashrc to save future headaches.

Set your preferred editor:

$ CVSEDITOR=vi

General syntax

CVS commands follow a simple-but-old-school pattern:

$ cvs cvs-options subcommand subcommand-options

Where subcommand is the thing you are asking cvs to do.

To see a full list of subcommands:

$ cvs --help

To get detailed syntax for a specific subcommand:

$ cvs -H subcommand

Note

Think of CVS syntax like a riddle written in the 1980s — it works if you know the secret handshake.

Dowloading files

Checkout an existing directory:

$ cvs co dir

Checkout without recursion:

$ cvs co -l dir

Update your working directory:

$ cvs up -d

List contents of the current directory:

$ cvs ls

Note

CVS doesn’t automatically tell you everything — it expects you to know what you’re doing. Like an old-school mentor.

Uploading changes

After modifying your files:

Commit changes:

$ cvs ci -m 'commit message'

Note

Remember: CVS commits are sacred. It trusts you to preserve history… or at least not destroy it entirely.

Checking differences

See what has changed in your working copy:

$ cvs status

Note

Pro tip: cvs diff is your friend. Treat it like a telescope for observing the tiny ripples you’ve made in the timeline.

Adding files and directories

Add a new directoy:

$ mkdir newdir
$ cvs add newdir

Add a new file:

# create file
$ cvs add newfile
$ cvs ci -m 'message'

Merging revisions

If your file is out of date with the repository version, CVS will require you to merge changes manually. Think of it as carefully combining two timelines without causing a paradox.

Note

CVS doesn’t do hand-holding. If two changes collide, you decide which timeline survives.

Resolving conflicts

CVS inserts conflict markers when it detects overlapping edits:

<<<<<file
some output
==================
some other output
>>>>>

Edit the file, remove the conflict markers, and then commit.

Note

Patience is a virtue. CVS expects you to be the arbiter of history.

Deleting files

$ rm filename           # remove local copy first
$ cvs delete filename   # mark file for removal from repository
$ cvs commit            # commfinalize deletionit

Note

CVS likes a ceremonial approach — remove locally first, then let it know remotely, then commit.

Other useful commands

Show differences between your local copy and the repository version:

$ cvs diff filename
$ cvs diff -r 1.2 filename           # Compare with version 1.2
$ cvs diff -r 1.2 -r 1.3 filename    # Compare version 1.2 with 1.3

Show commit log for a file:

$ cvs log filename

Annotate a file (see who changed each line):

$ cvs annotate filename

Note

Useful for figuring out “who touched this timeline and why.”