Man page for crc32(1)

Man page for crc32(1)


sha1, sha256, crc32 - compute hashes or checksums of streams and files


sha1 [options] [file...]
sha256 [options] [file...]
crc32 [options] [file...]


sha1, sha256, and crc32 are utilities for computing the SHA-1 cryptographic hash function, the SHA-256 cryptographic hash function, and the CRC-32 checksum, respectively. They operate on character streams of any length. sha1 computes a 20-byte hash, sha256 computes a 32-byte hash, and crc32 computes a 4-byte checksum.

The output is a sequence of lines, one for each file, of the form
347b40d5e85365fa11e2c1cf6cb8c80c288c39fb filename

If no filename is given on the command line, the input is read from stdin.


The following options are supported:

-h, --help
Help. Print usage information and exit.

-v, --version
Print version and copyright info and exit.

-l, --license
Print license and copyright info and exit.

-r, --recursive
Traverse subdirectories recursively.

-q, --quiet
Suppress warnings.


The exit status is 1 if an illegal command line was given, and otherwise 0. Errors, such as missing files, are reported, but do not lead to a non-zero exit status.


sha1 and sha256 aim to conform to the U.S. Government's Secure Hash Standard, FIPS PUB 180-2, although this has not been officially certified. Unlike the standard, these programs can (in principle) handle input streams that are longer than 2^64 bits. See




Peter Selinger,


Copyright (C) 2000-2007 Peter Selinger.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA. See also