CKSUM(1)

📦
version 9.12 · 28 versions
, in arch rolling

💖 CKSUM(1) — the girlies' guide to checksums 💖

okay bestie, welcome to cksum, section 1 of the User Commands manual, and honestly? this one's a whole personality. she computes and verifies file checksums, she's been in GNU coreutils forever, and she has opinions. let's get into it 🦋

✨ NAME ✨

cksum — compute and verify file checksums. that's it, that's the vibe 💅

✨ SYNOPSIS ✨

cksum [OPTION]... [FILE]...

✨ DESCRIPTION ✨

so what does she actually do? she prints checksums, or she verifies them. no cap. and by default she's rocking the 32 bit CRC algorithm, which is giving old school but still iconic.

if you give her no FILE at all, or if FILE is literally just -, she reads from standard input. standard input is her comfort zone fr fr 🌸

and listen — mandatory arguments to long options are mandatory for short options too. that's not a suggestion, that's the rules. periodt.

  • -a, --algorithm=TYPE — pick which digest type you wanna use. the full roster is down in DIGEST, keep scrolling babe 👑
  • --base64 — emits base64-encoded digests instead of hexadecimal. she's switching up the aesthetic ✨
  • -c, --check — reads checksums from the *FILE*s and checks them. this is the verification era 🎀
  • -l, --length=BITS — digest length in bits. okay so the rules here: it must not exceed the max size, and it must be a multiple of 8 for blake2b. for sha2 or sha3 it must be 224, 256, 384, or 512. no in-between, she doesn't do in-between 💀
  • --raw — emits a raw binary digest, not hexadecimal. feral. unhinged. love that for her 🫶
  • --tag — creates a BSD-style checksum. and btw, this one is the default, so she's already doing it 💅
  • --untagged — creates a reversed style checksum, without digest type. minimal, no labels, main character energy ✨
  • -z, --zero — ends each output line with NUL instead of newline, and disables file name escaping. yes really, NUL. she said no newlines today 🙈

🧚 the following five options are useful only when verifying checksums 🧚

  • --ignore-missing — don't fail or report status for missing files. she's being chill about it 😌
  • --quiet — don't print OK for each successfully verified file. silent but slaying 🔥
  • --status — don't output anything at all; the status code shows success. literally zero words, all information, the way that she communicates 💜
  • --strict — exit non-zero for improperly formatted checksum lines. she's strict, she said what she said ⭐
  • -w, --warn — warn about improperly formatted checksum lines. not a threat, a promise 🌈
  • --debug — indicate which implementation used. she's telling you exactly which one of her showed up 👑
  • --help — display this help and exit. classic, beloved, we stan 🎀
  • --version — output version information and exit. also classic. also beloved. 💖

🌸 DIGEST determines the digest algorithm and default output format 🌸

here's the whole roster bestie, every single one, no skips:

  • sysv — (equivalent to sum -s)
  • bsd — (equivalent to sum -r)
  • crc — (equivalent to cksum)
  • crc32b — (only available through cksum)
  • 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)

and when checking? the input should be a former output of this program, or an equivalent standalone program. she's not out here verifying just anything, she needs receipts 🧾

✨ AUTHOR ✨

written by Padraig Brady and Q. Frank Xia. legends, honestly. we owe them everything 🫶

✨ REPORTING BUGS ✨

found a bug? don't just suffer in silence, bestie, tell someone:

Copyright © 2026 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.

this is free software: you are free to change and redistribute it. and listen — there is NO WARRANTY, to the extent permitted by law. like, none. zero. she said it clearly 😭

✨ SEE ALSO ✨

and that's the page babe 💅 this was GNU coreutils 9.12, dated September 2026 — cksum manual page, section 1, out. go verify something, you absolute icon 👑✨

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