Zcmp and zdiff are used to invoke the cmp or the diff program on files compressed via gzip. All options spec-
ified 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.