rdiff [ flags] [ V vn] [ r t| D d [ r t2| D d2]] modules...

Changes: nothing.

Synonym: patch

Builds a Larry Wall format patch(1) file between two releases, that can be fed directly into the patch program to bring an old release up to date with the new release. (This is one of the few cvs commands that operates directly from the repository, and doesn't require a prior checkout.) The diff output is sent to the standard output device. You can specify (using the standard -r and -D options) any combination of one or two revisions or dates. If only one revision or date is specified, the patch file reflects differences between that revision or date and the current "head" revisions in the RCS file.

Note that if the software release affected is contained in more than one directory, then it may be necessary to specify the -p option to the patch command when patching the old sources, so that patch is able to find the files that are located in other directories.

If you use the option -V vn, RCS keywords are expanded according to the rules current in RCS version vn (the expansion format changed with RCS version 5).

The standard option flags -f, -l, -Q, and -q are available with this command. There are also several special options flags:

If you use the -s option, no patch output is produced. Instead, a summary of the files changed or added between the two releases is sent to the standard output device. This is useful for finding out, for example, which files have changed between two dates or revisions.

If you use the -t option, a diff of the top two revisions is sent to the standard output device. This is most useful for seeing what the last change to a file was.

If you use the -u option, the patch output uses the newer "unidiff" format for context diffs.

You can use -c to explicitly specify the 'diff -c' form of context diffs (which is the default), if you like.