brotli


NAME

brotli - brotli, unbrotli - compress or decompress files

SYNOPSIS

brotli [OPTION|FILE]...

unbrotli is equivalent to brotli --decompress

DESCRIPTION

brotli is a generic-purpose lossless compression algorithm that compresses data using a combination of a modern variant of the LZ77 algorithm, Huffman coding and 2-nd order context modeling, with a compression ratio comparable to the best currently available general-purpose compression methods. It is similar in speed with deflate but offers more dense compression.

brotli command line syntax similar to gzip (1) and zstd (1) . Unlike gzip (1), source files are preserved by default. It is possible to remove them after processing by using the --rm option .

Arguments that look like "--name" or "--name=value" are options . Every option has a short form "-x" or "-x value". Multiple short form options could be coalesced:

--decompress --stdout --suffix=.b

works the same as

-d -s -S .b

and

-dsS .b

brotli has 3 operation modes:

  • default mode is compression;

  • --decompress option activates decompression mode;

  • --test option switches to integrity test mode; this option is equivalent to "--decompress --stdout" except that the decompressed data is discarded instead of being written to standard output.

Every non-option argument is a file entry. If no files are given or file is "-", brotli reads from standard input. All arguments after "--" are file entries.

Unless --stdout or --output is specified, files are written to a new file whose name is derived from the source file name:

  • when compressing, a suffix is appended to the source filename to get the target filename

  • when decompressing, a suffix is removed from the source filename to get the target filename

Default suffix is  .br, but it could be specified with --suffix option.

Conflicting or duplicate options are not allowed.

OPTIONS

-#

compression level (0-9); bigger values cause denser, but slower compression

-c, --stdout

write on standard output

-d, --decompress

decompress mode

-f, --force

force output file overwrite

-h, --help

display this help and exit

-j, --rm

remove source file(s); gzip (1)-like behaviour

-k, --keep

keep source file(s); zstd (1)-like behaviour

-n, --no-copy-stat

do not copy source file(s) attributes

-o FILE, --output=FILE output file

valid only if there is a single input entry

-q NUM, --quality=NUM

compression level (0-11); bigger values cause denser, but slower compression

-t, --test

test file integrity mode

-v, --verbose

increase output verbosity

-w NUM, --lgwin=NUM

set LZ77 window size (0, 10-24) (default: 22); window size is (2**NUM - 16); 0 lets compressor decide over the optimal value; bigger windows size improve density; decoder might require up to window size memory to operate

-S SUF, --suffix=SUF

output file suffix (default:  .br)

-V, --version

display version and exit

-Z, --best

use best compression level (default); same as "-q 11"

SEE ALSO

brotli file format is defined in RFC 7932 https://www.ietf.org/rfc/rfc7932.txt .

brotli is open-sourced under the MIT License https://opensource.org/licenses/MIT .

Mailing list: https://groups.google.com/forum/#!forum/brotli

BUGS

Report bugs at: https://github.com/google/brotli/issues