ZDIFF linux command manual
zcmp, zdiff - compare compressed files
zcmp [ cmp_options ] file1 [ file2 ]
zdiff [ diff_options ] file1 [ file2 ]
Zcmp and zdiff are used to invoke the cmp or the diff program on com-
pressed files. All options specified are passed directly to cmp or
diff. If only 1 file is specified, then the files compared are file1
and an uncompressed file1.gz. If two files are specified, then they
are uncompressed if necessary and fed to cmp or diff. The exit status
from cmp or diff is preserved.
cmp(1), diff(1), zmore(1), zgrep(1), znew(1), zforce(1), gzip(1),
Messages from the cmp or diff programs refer to temporary filenames
instead of those specified.