6.4 md5sum: Print or check MD5 digests

md5sum computes a 128-bit checksum (or fingerprint or message-digest) for each specified file.

The MD5 digest is more reliable than a simple CRC (provided by the cksum command) for detecting accidental file corruption, as the chances of accidentally having two files with identical MD5 are vanishingly small. However, it should not be considered secure against malicious tampering: although finding a file with a given MD5 fingerprint is considered infeasible at the moment, it is known how to modify certain files, including digital certificates, so that they appear valid when signed with an MD5 digest. For more secure hashes, consider using SHA-2 or b2sum. See sha2 utilities: Print or check SHA-2 digests. See b2sum: Print or check BLAKE2 digests.

If a file is specified as ‘-’ or if no files are given md5sum computes the checksum for the standard input. md5sum can also determine whether a file and checksum are consistent. Synopsis:

md5sum [option]… [file]…

md5sum uses the ‘Untagged output format’ for each specified file, as described at cksum output modes.

The program accepts cksum common options. Also see Common options.

An exit status of zero indicates success, and a nonzero value indicates failure.