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6.3.2 cksum general options ¶

‘-a type’ ¶

‘--algorithm=type’

Compute checksums using the specified digest algorithm.

Supported legacy checksums (which are not supported by --check):

‘sysv’      equivalent to sum -s
‘bsd’       equivalent to sum -r
‘crc’       equivalent to cksum (the default)
‘crc32b’    only available through cksum

Supported more modern digest algorithms are:

‘md5’       equivalent to md5sum
‘sha1’      equivalent to sha1sum
‘sha2’      equivalent to sha{224,256,384,512}sum
‘sha3’      only available through cksum
‘blake2b’   equivalent to b2sum
‘sm3’       only available through cksum

The following algorithms are currently considered secure against malicious tampering, i.e., there is no known way to modify a file to produce the same checksum:

‘sha2’      equivalent to sha{224,256,384,512}sum
‘sha3’      only available through cksum
‘blake2b’   equivalent to b2sum

‘--base64’ ¶

Print base64-encoded digests not hexadecimal. This option is ignored with --check. The format conforms to RFC 4648#4.

Each base64-encoded digest has zero, one or two trailing padding (‘=’) bytes. The length of that padding is the checksum-bit-length modulo 3, and the --check parser requires precisely the same input digest string as what is output. I.e., removing or adding any ‘=’ padding renders a digest non-matching.

‘--debug’ ¶

Output extra information to standard error, like the checksum implementation being used.

‘-l bits’ ¶

‘--length=bits’

Specify the digest size used with -a sha2, sha3, or blake2b. For ‘blake2b’ this is optional, with 512 being the default. If the option is given it must be a multiple of 8. For ‘sha2’ or ‘sha3’ this option is required, and the length must be one of 224, 256, 384, or 512.

This option is ignored when --check is specified, as the length is automatically determined when checking.

‘--raw’ ¶

Print only the unencoded raw binary digest for a single input. Do not output the file name or anything else. Use network byte order (big endian) where applicable: for ‘bsd’, ‘crc’, ‘crc32b’, and ‘sysv’. This option works only with a single input. Unlike other output formats, cksum provides no way to --check a --raw checksum.

‘--untagged’ ¶

Output using the original Coreutils format used by the other standalone checksum utilities like md5sum for example. This format has the checksum at the start of the line, and may be more amenable to further processing by other utilities, especially in combination with the --zero option. This does not identify the digest algorithm used for the checksum. See cksum output modes for details of this format.