Usage: shasum [OPTION] [FILE]... or: shasum [OPTION] --check [FILE] Print or check SHA checksums. With no FILE, or when FILE is -, read standard input. -a, --algorithm 1 (default), 224, 256, 384, 512 -b, --binary read files in binary mode (default on DOS/Windows) -c, --check check SHA sums against given list -p, --portable read files in portable mode produces same digest on Windows/Unix/Mac -t, --text read files in text mode (default) The following two options are useful only when verifying checksums: -s, --status don't output anything, status code shows success -w, --warn warn about improperly formatted SHA checksum lines -h, --help display this help and exit -v, --version output version information and exit The sums are computed as described in FIPS PUB 180-2. When checking, the input should be a former output of this program. The default mode is to print a line with checksum, a character indicating type (`*' for binary, `?' for portable, ` ' for text), and name for each FILE.
The following command shows how easy it is to compute digests for typical inputs such as the NIST test vector ``abc'':
perl -e "print qw(abc)" | shasum
Or, if you want to use SHA-256 instead of the default SHA-1, simply say:
perl -e "print qw(abc)" | shasum -a 256
Since shasum uses the same interface employed by the familiar sha1sum program (and its somewhat outmoded anscestor md5sum), you can install this script as a convenient drop-in replacement.