b2sum - Man Page
compute and check BLAKE2 message digest
Examples (TL;DR)
- Calculate the BLAKE2 checksum for one or more files:
b2sum path/to/file1 path/to/file2 ... - Calculate and save the list of BLAKE2 checksums to a file:
b2sum path/to/file1 path/to/file2 ... > path/to/file.b2 - Calculate a BLAKE2 checksum from
stdin:command | b2sum - Read a file of BLAKE2 checksums and filenames and verify all files have matching checksums:
b2sum [-c|--check] path/to/file.b2 - Only show a message for missing files or when verification fails:
b2sum [-c|--check] --quiet path/to/file.b2 - Only show a message when verification fails, ignoring missing files:
b2sum --ignore-missing [-c|--check] --quiet path/to/file.b2 - Check a known BLAKE2 checksum of a file:
echo known_blake2_checksum_of_the_file path/to/file | b2sum [-c|--check]
Synopsis
b2sum [OPTION]... [FILE]...
Description
Print or check BLAKE2b (512-bit) checksums.
With no FILE, or when FILE is -, read standard input.
Mandatory arguments to long options are mandatory for short options too.
- -b, --binary
read in binary mode
- -c, --check
read checksums from the FILEs and check them
- -l, --length=BITS
digest length in bits; must not exceed the max for the blake2 algorithm and must be a multiple of 8
- --tag
create a BSD-style checksum
- -t, --text
read in text mode (default)
- -z, --zero
end each output line with NUL, not newline, and disable file name escaping
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
- --help
display this help and exit
- --version
output version information and exit
The sums are computed as described in RFC 7693. When checking, the input should be a former output of this program. The default mode is to print a line with: checksum, a space, a character indicating input mode ('*' for binary, ' ' for text or where binary is insignificant), and name for each FILE.
There is no difference between binary mode and text mode on GNU systems.
Author
Written by Padraig Brady and Samuel Neves.
Reporting Bugs
GNU coreutils online help: <https://www.gnu.org/software/coreutils/>
Report any translation bugs to <https://translationproject.org/team/>
Copyright
Copyright © 2025 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.
See Also
Full documentation <https://www.gnu.org/software/coreutils/b2sum>
or available locally via: info '(coreutils) b2sum invocation'