mkdir RCS
ci -u file.pl # check in file (inital touched version)
co -l file.pl # check out file to make revisions
....
rlog file.pl # history of a file
rcsdiff -r1.2 file.pl # diff versions of files
co -r1.2 file.pl # get an earlier version of a file
####
my $v = q{$Id$};
print "$v\n";
or simply
# $Id$
##
##
rlog file.pl # display a log history of the file changes from version to version...