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* `--tag`:
  Output in the BSD style.

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

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

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

### Advanced file input options

* `--files-from`, `--filelist` *FILE*:
  Read filenames from *FILE* and generate hashes for them.
  `stdin` is also a valid way to provide filenames (when no *FILE* or `-` provided).
  Valid format is one filename per line, which can include embedded spaces, etc with no need for quotes, escapes, etc.
  A line commencing with '\\' will enable the convention used in the encoding of filenames against output hashes,
  whereby subsequent \\\\, \n and \r sequences are converted to the single
  character 0x5C, 0x0A and 0x0D respectively.

### The following options are useful only for checksum verification:

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

* `--strict`:
  Return an error code if any line in *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.

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

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

* `--status`:
  Don't output anything. Only generate a Status code to show success.

### The following options are useful only benchmark purpose:

* `-b`:
  Benchmark mode.  See 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* 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* 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

Produce a list of files, then generate hashes for that list

    $ find . -type f -name '*.[ch]' > c-files.txt
    $ xxhsum --files-from c-files.txt

Read the list of files from standard input to avoid the need for an intermediate file

    $ find . -type f -name '*.[ch]' | xxhsum --files-from -

Note that if shell expansion, length of argument list, clarity of use of spaces in filenames, etc allow it then the same output as the previous example can be generated like this

    $ xxhsum `find . -name '*.[ch]'`

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/