checksum - helper program for calculating checksums
$ b2sum [options...] <file...>
$ md5sum [options...] <file...>
$ sha1sum [options...] <file...>
$ sha256sum [options...] <file...>
$ sha512sum [options...] <file...>
This program calculates and print specified checksum of files. It cannot be run directly, only as b2sum, md5sum, sha1sum, sha256sum or sha512sum. A non-zero exit code is returned if the input cannot be read. If the '--check' option is used, a non-zero exit code is also returned if the checksums cannot be verified.
-c, --check: Verify checksums against file or stdin.