---
name: "b3sum"
section: "1"
platform: "linux"
package: "b3sum"
version: "1.8.1-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/b3sum"
---

# b3sum(1)

b3sum

## NAME

b3sum - b3sum

## SYNOPSIS

**b3sum** \[*OPTIONS*\] \[*FILE*\]...

## DESCRIPTION

### Arguments:

-

  \[FILE\]...

-

  Files to hash, or checkfiles to check

-

  When no file is given, or when - is given, read standard input.

## OPTIONS

**--keyed**

-

  Use the keyed mode, reading the 32-byte key from stdin

**--derive-key** \<CONTEXT\>

-

  Use the key derivation mode, with the given context string

-

  Cannot be used with **--keyed**.

**-l**, **--length** \<LEN\>

-

  The number of output bytes, before hex encoding

-

  \[default: 32\]

**--seek** \<SEEK\>

-

  The starting output byte offset, before hex encoding

-

  \[default: 0\]

**--num-threads** \<NUM\>

-

  The maximum number of threads to use

-

  By default, this is the number of logical cores. If this flag is omitted, or if its value is 0, RAYON\_NUM\_THREADS is also respected.

**--no-mmap**

-

  Disable memory mapping

-

  Currently this also disables multithreading.

**--no-names**

-

  Omit filenames in the output

**--raw**

-

  Write raw output bytes to stdout, rather than hex

**--no-names** is implied. In this case, only a single input is allowed.

**--tag**

-

  Output BSD-style checksums: BLAKE3 (\[FILE\]) = \[HASH\]

**-c**, **--check**

-

  Read BLAKE3 sums from the \[FILE\]s and check them

**--quiet**

-

  Skip printing OK for each checked file

-

  Must be used with **--check**.

**-h**, **--help**

-

  Print help (see a summary with '-h')

**-V**, **--version**

-

  Print version