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md5sum
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(All other hashes have the same options and usage.)
shasum
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The md5sum, sha512t224sum, and skein1024sum utilities do the same, but with command-line options and an output format that match those of their similary named GNU utilities.
The shasum utility does the same, but with command-line options and an output format that match those of the similarly named utility that ships with Perl.
In all cases, each file listed on the command line is processed separately. If no files are listed on the command line, or a file name is given as -, input is taken from stdin instead.
It is conjectured that it is computationally infeasible to produce two messages having the same message digest, or to produce any message having a given prespecified target message digest. The SHA-224 , SHA-256 , SHA-384 , SHA-512, RIPEMD-160, and SKEIN algorithms are intended for digital signature applications, where a large file must be "compressed" in a secure manner before being encrypted with a private (secret) key under a public-key cryptosystem such as RSA.
The MD5 and SHA-1 algorithms have been proven to be vulnerable to practical collision attacks and should not be relied upon to produce unique outputs, nor should they be used as part of a cryptographic signature scheme. As of 2017-03-02, there is no publicly known method to reverse either algorithm, i.e., to find an input that produces a specific output.
SHA-512t256 is a version of SHA-512 truncated to only 256 bits. On 64-bit hardware, this algorithm is approximately 50% faster than SHA-256 but with the same level of security. The hashes are not interchangeable.
SHA-512t224 is identical to SHA-512t256, but with the digest truncated to 224 bits.
It is recommended that all new applications use SHA-512 or SKEIN-512 instead of one of the other hash functions.
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Compare the digest of the file against this string.
If combined with the
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Echo stdin to stdout and append the checksum to stdout. In this mode, any files specified on the command line are silently ignored. | |
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Quiet mode — only the checksum is printed out.
Overrides the
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Reverses the format of the output.
This helps with visual diffs.
Does nothing
when combined with the
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Print a checksum of the given string. In this mode, any files specified on the command line are silently ignored. | |
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Run a built-in time trial. For the -sum versions, this is a nop for compatibility with coreutils. | |
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Run a built-in test script. | |
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Read files in binary mode. | |
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The file passed as arguments must contain digest lines generated by the same
digest algorithm in either classical BSD format or in GNU coreutils format.
A line with the file name followed by a colon
":"
and either OK or FAILED is written for each well-formed line in the digest file.
If applicable, the number of failed comparisons and the number of lines that were
skipped since they were not well-formed are printed at the end.
The
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Print a usage message and exit. | |
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When verifying checksums, ignore files for which checksums are given but which aren't found on disk. | |
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When verifying checksums, do not print anything unless the verification fails. | |
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When verifying checksums, do not print anything at all. The exit code will reflect whether verification succeeded. | |
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When verifying checksums, fail if the input is malformed. | |
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Produce BSD-style output. | |
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Read files in text mode. This is the default. Note that this implementation does not differentiate between binary and text mode. | |
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Print version information and exit. | |
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When verifying checksums, warn about malformed input. | |
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Terminate output lines with NUL rather than with newline. | |
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Read files in bits mode: ASCII '0' and '1' characters correspond to 0 and 1 bits, respectively, and all other characters are ignored. See BUGS. | |
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Use the specified algorithm: "1" for SHA-1 (default), "xxx" for xxx-bit SHA-2 (e.g. "256" for SHA-256) or "xxxyyy" for xxx-bit SHA-2 truncated to yyy bits (e.g. "512224" for SHA-512/224). | |
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Read files in binary mode. | |
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The file passed as arguments must contain digest lines generated by the same
digest algorithm in either classical BSD format or in GNU coreutils format.
A line with the file name followed by a colon
":"
and either OK or FAILED is written for each well-formed line in the digest file.
If applicable, the number of failed comparisons and the number of lines that were
skipped since they were not well-formed are printed at the end.
The
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Print a usage message and exit. | |
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When verifying checksums, ignore files for which checksums are given but which aren't found on disk. | |
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When verifying checksums, do not print anything unless the verification fails. | |
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When verifying checksums, do not print anything at all. The exit code will reflect whether verification succeeded. | |
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When verifying checksums, fail if the input is malformed. | |
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Produce BSD-style output. | |
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Read files in text mode. This is the default. Note that this implementation does not differentiate between binary and text mode. | |
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Read files in universal mode: any CR-LF pair, as well as any CR not followed by LF, is translated to LF before the digest is computed. | |
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Print version information and exit. | |
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When verifying checksums, warn about malformed input. | |
The md5sum, sha512t224sum, rmd160 and shasum utilities exit 0 on success and 1 if at least one of the input files could not be read or, when verifying checksums, does not have the expected checksum.
$ md5 -s Hello MD5 ("Hello") = 8b1a9953c4611296a827abf8c47804d7
Same as above, but note the absence of the newline character in the input string:
$ echo -n Hello | md5 8b1a9953c4611296a827abf8c47804d7
Calculate the checksum of multiple files reversing the output:
$ md5 -r /boot/loader.conf /etc/rc.conf ada5f60f23af88ff95b8091d6d67bef6 /boot/loader.conf d80bf36c332dc0fdc479366ec3fa44cd /etc/rc.conf
This is almost but not quite identical to the output from GNU mode:
$ md5sum /boot/loader.conf /etc/rc.conf ada5f60f23af88ff95b8091d6d67bef6 /boot/loader.conf d80bf36c332dc0fdc479366ec3fa44cd /etc/rc.conf
Note the two spaces between hash and file name. If binary mode is requested, they are instead separated by a space and an asterisk:
$ md5sum -b /boot/loader.conf /etc/rc.conf ada5f60f23af88ff95b8091d6d67bef6 */boot/loader.conf d80bf36c332dc0fdc479366ec3fa44cd */etc/rc.conf
Write the digest for /boot/loader.conf in a file named digest. Then calculate the checksum again and validate it against the checksum string extracted from the digest file:
$ md5 /boot/loader.conf > digest && md5 -c $(cut -f2 -d= digest) /boot/loader.conf MD5 (/boot/loader.conf) = ada5f60f23af88ff95b8091d6d67bef6
Same as above but comparing the digest against an invalid string ("randomstring"), which results in a failure.
$ md5 -c randomstring /boot/loader.conf MD5 (/boot/loader.conf) = ada5f60f23af88ff95b8091d6d67bef6 [ Failed ]
In GNU mode, the
$ md5sum -c digest /boot/loader.conf: OK
The digest file may contain any number of lines in the format generated in either BSD or GNU mode. If a hash value does not match the file, "FAILED" is printed instead of "OK".
RFC1321, The MD5 Message-Digest Algorithm,
,FIPS PUB 180-2, The Secure Hash Standard,
,RFC 3174, US Secure Hash Algorithm 1,
,RIPEMD-160 is part of the ISO draft standard "ISO/IEC DIS 10118-3" on dedicated hash functions.
Secure Hash Standard (SHS): https://www.nist.gov/publications/secure-hash-standard-shs
The RIPEMD-160 page: https://homes.esat.kuleuven.be/~bosselae/ripemd160.html
Support for SHA-1 and RIPEMD-160 was added by Oliver Eikemeier <Mt eik@FreeBSD.org>.
Support for SHA-2 was added by Colin Percival <Mt cperciva@FreeBSD.org> and Allan Jude <Mt allanjude@FreeBSD.org>.
Support for SKEIN was added by Allan Jude <Mt allanjude@FreeBSD.org>.
Compatibility with GNU coreutils was added by Warner Losh <Mt imp@FreeBSD.org> and much expanded by Dag-Erling Sm/orgrav <Mt des@FreeBSD.org>, who also added Perl compatibility.
MD5 (1) | March 12, 2024 |
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