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.TH "brotli" "1" "August 14 2021" "brotli 1.0.9" "User Manual"
.hy
.SH NAME
.PP
brotli(1) -- brotli, brcat, unbrotli - compress or decompress files
.SH SYNOPSIS
.PP
\f[B]brotli\f[R] [\f[I]OPTION|FILE\f[R]]\&...
.PP
\f[B]brcat\f[R] is equivalent to \f[B]brotli --decompress --concatenated
--stdout\f[R]
.PP
\f[B]unbrotli\f[R] is equivalent to \f[B]brotli --decompress\f[R]
.SH DESCRIPTION
.PP
\f[B]brotli\f[R] is a generic-purpose lossless compression algorithm
that compresses data using a combination of a modern variant of the
\f[B]LZ77\f[R] 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.
.PP
\f[B]brotli\f[R] command line syntax similar to \f[B]gzip (1)\f[R] and
\f[B]zstd (1)\f[R].
Unlike \f[B]gzip (1)\f[R], source files are preserved by default.
It is possible to remove them after processing by using the
\f[B]--rm\f[R] \f[I]option\f[R].
.PP
Arguments that look like \[lq]\f[B]--name\f[R]\[rq] or
\[lq]\f[B]--name=value\f[R]\[rq] are \f[I]options\f[R].
Every \f[I]option\f[R] has a short form \[lq]\f[B]-x\f[R]\[rq] or
\[lq]\f[B]-x value\f[R]\[rq].
Multiple short form \f[I]options\f[R] could be coalesced:
.IP \[bu] 2
\[lq]\f[B]--decompress --stdout --suffix=.b\f[R]\[rq] works the same as
.IP \[bu] 2
\[lq]\f[B]-d -s -S .b\f[R]\[rq] and
.IP \[bu] 2
\[lq]\f[B]-dsS .b\f[R]\[rq]
.PP
\f[B]brotli\f[R] has 3 operation modes:
.IP \[bu] 2
default mode is compression;
.IP \[bu] 2
\f[B]--decompress\f[R] option activates decompression mode;
.IP \[bu] 2
\f[B]--test\f[R] option switches to integrity test mode; this option is
equivalent to \[lq]\f[B]--decompress --stdout\f[R]\[rq] except that the
decompressed data is discarded instead of being written to standard
output.
.PP
Every non-option argument is a \f[I]file\f[R] entry.
If no \f[I]files\f[R] are given or \f[I]file\f[R] is
\[lq]\f[B]-\f[R]\[rq], \f[B]brotli\f[R] reads from standard input.
All arguments after \[lq]\f[B]--\f[R]\[rq] are \f[I]file\f[R] entries.
.PP
Unless \f[B]--stdout\f[R] or \f[B]--output\f[R] is specified,
\f[I]files\f[R] are written to a new file whose name is derived from the
source \f[I]file\f[R] name:
.IP \[bu] 2
when compressing, a suffix is appended to the source filename to get the
target filename
.IP \[bu] 2
when decompressing, a suffix is removed from the source filename to get
the target filename
.PP
Default suffix is \f[B].br\f[R], but it could be specified with
\f[B]--suffix\f[R] option.
.PP
Conflicting or duplicate \f[I]options\f[R] are not allowed.
.SH OPTIONS
.IP \[bu] 2
\f[B]-#\f[R]: compression level (0-9); bigger values cause denser, but
slower compression
.IP \[bu] 2
\f[B]-c\f[R], \f[B]--stdout\f[R]: write on standard output
.IP \[bu] 2
\f[B]-d\f[R], \f[B]--decompress\f[R]: decompress mode
.IP \[bu] 2
\f[B]-f\f[R], \f[B]--force\f[R]: force output file overwrite
.IP \[bu] 2
\f[B]-h\f[R], \f[B]--help\f[R]: display this help and exit
.IP \[bu] 2
\f[B]-j\f[R], \f[B]--rm\f[R]: remove source file(s); \f[B]gzip
(1)\f[R]-like behaviour
.IP \[bu] 2
\f[B]-k\f[R], \f[B]--keep\f[R]: keep source file(s); \f[B]zstd
(1)\f[R]-like behaviour
.IP \[bu] 2
\f[B]-n\f[R], \f[B]--no-copy-stat\f[R]: do not copy source file(s)
attributes
.IP \[bu] 2
\f[B]-o FILE\f[R], \f[B]--output=FILE\f[R] output file; valid only if
there is a single input entry
.IP \[bu] 2
\f[B]-q NUM\f[R], \f[B]--quality=NUM\f[R]: compression level (0-11);
bigger values cause denser, but slower compression
.IP \[bu] 2
\f[B]-t\f[R], \f[B]--test\f[R]: test file integrity mode
.IP \[bu] 2
\f[B]-v\f[R], \f[B]--verbose\f[R]: increase output verbosity
.IP \[bu] 2
\f[B]-w NUM\f[R], \f[B]--lgwin=NUM\f[R]: set LZ77 window size (0, 10-24)
(default: 24); window size is \f[B](pow(2, NUM) - 16)\f[R]; 0 lets
compressor decide over the optimal value; bigger windows size improve
density; decoder might require up to window size memory to operate
.IP \[bu] 2
\f[B]-C B64\f[R], \f[B]--comment=B64\f[R]: set comment; argument is
base64-decoded first; when decoding: check stream comment; when
encoding: embed comment (fingerprint)
.IP \[bu] 2
\f[B]-D FILE\f[R], \f[B]--dictionary=FILE\f[R]: use FILE as raw (LZ77)
dictionary; same dictionary MUST be used both for compression and
decompression
.IP \[bu] 2
\f[B]-K\f[R], \f[B]--concatenated\f[R]: when decoding, allow
concatenated brotli streams as input
.IP \[bu] 2
\f[B]-S SUF\f[R], \f[B]--suffix=SUF\f[R]: output file suffix (default:
\f[B].br\f[R])
.IP \[bu] 2
\f[B]-V\f[R], \f[B]--version\f[R]: display version and exit
.IP \[bu] 2
\f[B]-Z\f[R], \f[B]--best\f[R]: use best compression level (default);
same as \[lq]\f[B]-q 11\f[R]\[rq]
.SH SEE ALSO
.PP
\f[B]brotli\f[R] file format is defined in RFC
7932 (https://www.ietf.org/rfc/rfc7932.txt).
.PP
\f[B]brotli\f[R] is open-sourced under the MIT
License (https://opensource.org/licenses/MIT).
.PP
Mailing list: https://groups.google.com/forum/#!forum/brotli
.SH BUGS
.PP
Report bugs at: https://github.com/google/brotli/issues