md5, sha1,
sha256, sha512 —
calculate a message digest (checksum)
for a file
md5 |
[-bcpqrtx] [-C
checklist] [-h
hashfile] [-s
string] [file ...] |
sha1 |
[-bcpqrtx] [-C
checklist] [-h
hashfile] [-s
string] [file ...] |
sha256 |
[-bcpqrtx] [-C
checklist] [-h
hashfile] [-s
string] [file ...] |
sha512 |
[-bcpqrtx] [-C
checklist] [-h
hashfile] [-s
string] [file ...] |
These utilities take as input a message of arbitrary length and
produce as output a message digest (checksum) of the input.
Two messages having the same message digest (a collision) have
been produced for MD5 and for SHA-1, so their use is deprecated.
The options for use with each command are as follows:
-b- Output checksums in base64 notation, not hexadecimal.
-C
checklist- Compare the checksum of each file against the
checksums in the checklist. Any specified
file that is not listed in the
checklist will generate an error.
-c- If this option is specified, the file options become
checklists. Each checklist should contain hash results, which will be
verified against the specified paths. Both normal (BSD) and reverse (GNU)
forms are supported in either hexadecimal or base64 format. Output
consists of the digest used, the file name, and an OK, FAILED, or MISSING
for the result of the comparison. Entries in normal format can be
validated using any of the supported checksums (see
cksum(1)).
Entries in reverse format are validated using the default algorithm. If no
file is given, stdin is used.
-h
hashfile- Place the checksum into hashfile instead of
stdout.
-p- Echo stdin to stdout and append the checksum to stdout.
-q- Only print the checksum (quiet mode) or if used in conjunction with the
-c flag, only print the failed cases.
-r- Reverse the format of the hash algorithm output, similar to the output
format used by cksum(1) (but without the number of octets). This is also the
format used by the GNU cksum(1) utility.
-s
string- Print a checksum of the given string.
-t- Run a built-in time trial. Specifying
-t multiple
times results in the number of rounds being multiplied by 10 for each
additional flag.
-x- Run a built-in test script.
These utilities exit 0 on success, and >0 if an error
occurs.
R. Rivest,
The MD5 Message-Digest Algorithm,
RFC
1321, April 1992.
J. Burrows, The
Secure Hash Standard, FIPS PUB
180-1.
D. Eastlake and
P. Jones, US Secure Hash
Algorithm 1 (SHA1),
RFC
3174, September 2001.
Secure Hash Standard,
FIPS PUB 180-2.