info > sha1sum(1)

File: coreutils.info,  Node: sha1sum invocation,  Next: sha2 utilities,  Prev: b2sum invocation,  Up: Summarizing files

6.6 'sha1sum': Print or check SHA-1 digests

'sha1sum' computes a 160-bit checksum for each specified FILE.

   Note: The SHA-1 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 SHA-1 are
vanishingly small.  However, it should not be considered secure against
malicious tampering: although finding a file with a given SHA-1
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 SHA-1 digest.  For more secure hashes,
consider using SHA-2, or the newer 'b2sum' command.  *Note sha2
utilities::.  *Note b2sum invocation::.

   If a FILE is specified as '-' or if no files are given 'sha1sum'
computes the checksum for the standard input.  'sha1sum' can also
determine whether a file and checksum are consistent.  Synopsis:

     sha1sum [OPTION]... [FILE]...

   'sha1sum' uses the 'Untagged output format' for each specified file,
as described at *note cksum output modes::.

   The program accepts *note cksum common options::.  Also see *note
Common options::.