compute and check BLAKE2 message digest


Calculate the BLAKE2 checksum for a file

$ b2sum [path/to/file]

Calculate BLAKE2 checksums for multiple files
$ b2sum [path/to/file1] [path/to/file2]

Calculate the BLAKE2 checksum from stdin
$ [some_command] | b2sum

Read a file of BLAKE2 sums and filenames and verify all files have matching checksums
$ b2sum --check [path/to/file.b2]

Only show a message for missing files or when verification fails
$ b2sum --check --quiet [path/to/file.b2]

Only show a message for files for which verification fails, ignoring missing files
$ b2sum --ignore-missing --check --quiet [path/to/file.b2]


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


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


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:


don't fail or report status for missing files


don't print OK for each successfully verified file


don't output anything, status code shows success


exit non-zero for improperly formatted checksum lines

-w, --warn

warn about improperly formatted checksum lines


display this help and exit


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.

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


GNU coreutils online help: <>
Report any translation bugs to <>


Copyright © 2022 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <>.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.


cksum(1) Full documentation <> or available locally via: info '(coreutils) b2sum invocation'


Written by Padraig Brady and Samuel Neves.

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