xxHash/xxhsum.1.md

xxhsum(1) -- print or check xxHash non-cryptographic checksums
==============================================================

SYNOPSIS
--------

`xxhsum [<OPTION>] ... [<FILE>] ...`
`xxhsum -b [<OPTION>] ...`

`xxh32sum` is equivalent to `xxhsum -H0`
`xxh64sum` is equivalent to `xxhsum -H1`
`xxh128sum` is equivalent to `xxhsum -H2`


DESCRIPTION
-----------

Print or check xxHash (32, 64 or 128 bits) checksums.  When <FILE> is `-`, read
standard input.

`xxhsum` supports a command line syntax similar but not identical to
md5sum(1).  Differences are:
`xxhsum` doesn't have text/binary mode switch (`-b`, `-t`);
`xxhsum` always treats files as binary file;
`xxhsum` has a hash bit width switch (`-H`);

As xxHash is a fast non-cryptographic checksum algorithm,
`xxhsum` should not be used for security related purposes.

`xxhsum -b` invokes benchmark mode. See [OPTIONS](#OPTIONS) and [EXAMPLES](#EXAMPLES) for details.

OPTIONS
-------

* `-V`, `--version`:
  Displays xxhsum version and exits

* `-H`<HASHTYPE>:
  Hash selection. <HASHTYPE> means `0`=32bits, `1`=64bits, `2`=128bits.
  Default value is `1` (64bits)

* `--little-endian`:
  Set output hexadecimal checksum value as little endian convention.
  By default, value is displayed as big endian.

* `-h`, `--help`:
  Displays help and exits

**The following four options are useful only when verifying checksums (`-c`)**

* `-c`, `--check` <FILE>:
  Read xxHash sums from <FILE> and check them

* `-q`, `--quiet`:
  Don't print OK for each successfully verified file

* `--strict`:
  Return an error code if any line in the file is invalid,
  not just if some checksums are wrong.
  This policy is disabled by default,
  though UI will prompt an informational message
  if any line in the file is detected invalid.

* `--status`:
  Don't output anything. Status code shows success.

* `-w`, `--warn`:
  Emit a warning message about each improperly formatted checksum line.

**The following options are useful only benchmark purpose**

* `-b`:
  Benchmark mode.  See [EXAMPLES](#EXAMPLES) for details.

* `-b#`:
  Specify ID of variant to be tested.
  Multiple variants can be selected, separated by a ',' comma.

* `-B`<BLOCKSIZE>:
  Only useful for benchmark mode (`-b`). See [EXAMPLES](#EXAMPLES) for details.
  <BLOCKSIZE> specifies benchmark mode's test data block size in bytes.
  Default value is 102400

* `-i`<ITERATIONS>:
  Only useful for benchmark mode (`-b`). See [EXAMPLES](#EXAMPLES) for details.
  <ITERATIONS> specifies number of iterations in benchmark. Single iteration
  lasts approximately 1000 milliseconds. Default value is 3

EXIT STATUS
-----------

`xxhsum` exit `0` on success, `1` if at least one file couldn't be read or
doesn't have the same checksum as the `-c` option.

EXAMPLES
--------

Output xxHash (64bit) checksum values of specific files to standard output

    $ xxhsum -H1 foo bar baz

Output xxHash (32bit and 64bit) checksum values of specific files to standard
output, and redirect it to `xyz.xxh32` and `qux.xxh64`

    $ xxhsum -H0 foo bar baz > xyz.xxh32
    $ xxhsum -H1 foo bar baz > qux.xxh64

Read xxHash sums from specific files and check them

    $ xxhsum -c xyz.xxh32 qux.xxh64

Benchmark xxHash algorithm.
By default, `xxhsum` benchmarks xxHash main variants
on a synthetic sample of 100 KB,
and print results into standard output.
The first column is the algorithm,
the second column is the source data size in bytes,
the third column is the number of hashes generated per second (throughput),
and finally the last column translates speed in megabytes per second.

    $ xxhsum -b

In the following example,
the sample to hash is set to 16384 bytes,
the variants to be benched are selected by their IDs,
and each benchmark test is repeated 10 times, for increased accuracy.

    $ xxhsum -b1,2,3 -i10 -B16384

BUGS
----

Report bugs at: https://github.com/Cyan4973/xxHash/issues/

AUTHOR
------

Yann Collet

SEE ALSO
--------

md5sum(1)