B2SUM(1)

📦
version 9.12 · 23 versions
, in arch rolling

💅 b2sum — it's giving BLAKE2, bestie

okay so this is the b2sum page from the User Commands section of the GNU coreutils manual, and it's literally about computing and checking BLAKE2 message digests. Yes, that's the whole vibe. Let's go. 🦋

✨ NAME ✨

b2sum — compute and check BLAKE2 message digest 💖

🌸 SYNOPSIS 🌸

b2sum [OPTION]... [FILE]...

🎀 DESCRIPTION 🎀

So what does it do? It prints or checks BLAKE2b (512-bit) checksums. That's it, that's the job. It's the legacy interface to the cksum(1) utility, iykyk. 👑

If you give it no FILE at all, or if FILE is literally -, it reads from standard input. Classic.

Also, real talk: mandatory arguments to long options are mandatory for short options too. That's not a suggestion, that's the rules. 🙈

🫶 the options, babes

  • -b, --binary — read in binary mode
  • -c, --check — read checksums from the FILEs and check them
  • -l, --length=BITS — digest length in bits; 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
  • --tag — create a BSD-style checksum
  • -t, --text — read in text mode (this is the default, so it's the chill one)
  • -z, --zero — end each output line with NUL, not newline, and disable file name escaping
  • --help — display this help and exit
  • --version — output version information and exit

🔍 the following five options are useful only when verifying checksums:

  • --ignore-missing — don't fail or report status for missing files
  • --quiet — don't print OK for each successfully verified file
  • --status — don't output anything, status code shows success
  • --strict — exit non-zero for improperly formatted checksum lines
  • -w, --warn — warn about improperly formatted checksum lines

The sums are computed exactly as described in RFC 7693, no cap. 🧚

When you're checking, the input should be a former output of this program — like, it has to be your own past receipts, okay?

The default mode is to print a line with: the checksum, a space, a character indicating the input mode ('*' for binary, ' ' for text or where binary is insignificant), and the name for each FILE. That's the whole format. Slay. ✨

There is no difference between binary mode and text mode on GNU systems. Periodt.

👑 AUTHOR 👑

Written by Padraig Brady and Samuel Neves. Icons, honestly.

😭 REPORTING BUGS 😭

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.

There is NO WARRANTY, to the extent permitted by law. Fr fr, none. 💀

🌈 SEE ALSO 🌈

Full documentation <https://www.gnu.org/software/coreutils/b2sum> or available locally via: info '(coreutils) b2sum invocation'

and that's the whole page, bestie — this one's from GNU coreutils 9.12, dated September 2026, so it's fresh out the box 🎁✨ go check your checksums, you got this 💅🦋

📦 where this page comes from