There are some command_options that are used so often that you might have set up an alias or some other means to make sure you always specify that option. One example (the one that drove the implementation of the `.cvsrc' support, actually) is that many people find the default output of the `diff' command to be very hard to read, and that either context diffs or unidiffs are much easier to understand.
The `~/.cvsrc' file is a way that you can add default options to cvs_commands within cvs, instead of relying on aliases or other shell scripts.
The format of the `~/.cvsrc' file is simple. The file is searched for a line that begins with the same name as the cvs_command being executed. If a match is found, then the remainder of the line is split up (at whitespace characters) into separate options and added to the command arguments before any options from the command line.
the command `cvs checkout foo' would have the `-P' option added to the arguments, as well as `cvs co foo'.
With the example file above, the output from `cvs diff foobar' will be in unidiff format. `cvs diff -c foobar' will provide context diffs, as usual. Getting "old" format diffs would be slightly more complicated, because diff doesn't have an option to specify use of the "old" format, so you would need `cvs -f diff foobar'.
causes CVS to use compression level 6.