Pathnames matching an RCS suffix denote RCS files; all others denote working files. Names are paired as explained in ci(1).
The option -q suppresses diagnostic output. Zero, one, or two revisions may be specified with -r. The option -ksubst affects keyword substitution when extracting revisions, as described in co(1); for example, -kk -r1.1 -r1.2 ignores differences in keyword values when comparing revisions 1.1 and 1.2. To avoid excess output from locker name substitution, -kkvl is assumed if (1) at most one revision option is given, (2) no -k option is given, (3) -kkv is the default keyword substitution, and (4) the working file's mode would be produced by co -l. See co(1) for details about -T, -V, -x and -z. Otherwise, all options of diff(1) that apply to regular files are accepted, with the same meaning as for diff.
If both rev1 and rev2 are omitted, rcsdiff compares the latest revision on the default branch (by default the trunk) with the contents of the corresponding working file. This is useful for determining what you changed since the last checkin.
If rev1 is given, but rev2 is omitted, rcsdiff compares revision rev1 of the RCS file with the contents of the corresponding working file.
If both rev1 and rev2 are given, rcsdiff compares revisions rev1 and rev2 of the RCS file.
Both rev1 and rev2 may be given numerically or symbolically.
compares the latest revision on the default branch of the RCS file to the contents of the working file f.c.