Zcmp and zdiff are used to invoke the cmp or the diff program on files compressed via gzip. 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.