These docs are under active development and cover the v0.20 Kobicha security model.
Peios Learn
On this page
reference 2 min read

cksum

cksum is the general checksum command. Where each of the checksum commands is fixed to one algorithm, cksum does any of them — the algorithm is an option.

cksum [options] [file...]

$ cksum installer.iso
3915528286 372736000 installer.iso
$ cksum -a sha256 installer.iso
9f86d0818884...b1a5  installer.iso

With no -a, cksum computes a CRC checksum and prints the CRC value, the file's byte count, and the name. With -a, it behaves like the corresponding dedicated command.

Choosing the algorithm

Option Effect
-a, --algorithm=NAME Use the named algorithm.

NAME may be:

Name Algorithm
crc The default CRC.
crc32b A CRC-32 variant.
md5 MD5 — as md5sum.
sha1 SHA-1 — as sha1sum.
sha224, sha256, sha384, sha512 The SHA-2 family — as the matching sha*sum.
sha3 SHA-3.
blake2b BLAKE2b — as b2sum.
sm3 The SM3 hash.
sysv, bsd The legacy block checksums — as sum.

crc, crc32b, sha3, and sm3 are available only through cksum — there is no dedicated command for them.

Verifying

cksum checks files the same way the dedicated commands do:

Option Effect
-c, --check Read checksums and verify the files against them.
--ignore-missing Do not fail over listed files that are absent.
--quiet Print nothing for files that pass.
--status Print nothing; report only through the exit status.
-w, --warn Warn about malformed checksum lines.
--strict Fail on a malformed checksum line.

Output format

Option Effect
--tag Produce a tagged ALGORITHM (file) = hash line. The default for most algorithms.
--untagged Produce a plain hash file line.
--raw Output the raw binary digest, with nothing else.
--base64 Print the digest in base64 rather than hexadecimal.
-l, --length=BITS For an algorithm that supports it, produce a shorter digest.
-z, --zero End each output line with a NUL character.

Exit status

Code Meaning
0 Success — or, in check mode, every file verified.
1 In check mode, a file failed verification.
2 An error — a file could not be read, or an option was invalid.

See also