zdiff (1) - Linux Manuals
zdiff: compare compressed files
zcmp, zdiff - compare compressed files
SYNOPSISzcmp [ cmp_options ] file1 [ file2 ]
zdiff [ diff_options ] file1 [ file2 ]
DESCRIPTIONZcmp 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 file1 is specified, it is compared to the uncompressed contents of file1.gz. If two files are specified, their contents (uncompressed if necessary) are fed to cmp or diff. The input files are not modified. The exit status from cmp or diff is preserved.
BUGSMessages from the cmp or diff programs may refer to file names such as "-" instead of to the file names specified.