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140 lines
5.0 KiB
Groff
140 lines
5.0 KiB
Groff
.\" Automatically generated by Pandoc 2.7.3
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.\"
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.TH "brotli" "1" "August 14 2021" "brotli 1.0.9" "User Manual"
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.hy
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.SH NAME
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.PP
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brotli(1) -- brotli, brcat, unbrotli - compress or decompress files
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.SH SYNOPSIS
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.PP
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\f[B]brotli\f[R] [\f[I]OPTION|FILE\f[R]]\&...
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.PP
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\f[B]brcat\f[R] is equivalent to \f[B]brotli --decompress --concatenated
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--stdout\f[R]
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.PP
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\f[B]unbrotli\f[R] is equivalent to \f[B]brotli --decompress\f[R]
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.SH DESCRIPTION
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.PP
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\f[B]brotli\f[R] is a generic-purpose lossless compression algorithm
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that compresses data using a combination of a modern variant of the
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\f[B]LZ77\f[R] algorithm, Huffman coding and 2-nd order context
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modeling, with a compression ratio comparable to the best currently
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available general-purpose compression methods.
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It is similar in speed with deflate but offers more dense compression.
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.PP
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\f[B]brotli\f[R] command line syntax similar to \f[B]gzip (1)\f[R] and
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\f[B]zstd (1)\f[R].
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Unlike \f[B]gzip (1)\f[R], source files are preserved by default.
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It is possible to remove them after processing by using the
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\f[B]--rm\f[R] \f[I]option\f[R].
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.PP
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Arguments that look like \[lq]\f[B]--name\f[R]\[rq] or
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\[lq]\f[B]--name=value\f[R]\[rq] are \f[I]options\f[R].
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Every \f[I]option\f[R] has a short form \[lq]\f[B]-x\f[R]\[rq] or
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\[lq]\f[B]-x value\f[R]\[rq].
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Multiple short form \f[I]options\f[R] could be coalesced:
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.IP \[bu] 2
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\[lq]\f[B]--decompress --stdout --suffix=.b\f[R]\[rq] works the same as
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.IP \[bu] 2
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\[lq]\f[B]-d -s -S .b\f[R]\[rq] and
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.IP \[bu] 2
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\[lq]\f[B]-dsS .b\f[R]\[rq]
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.PP
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\f[B]brotli\f[R] has 3 operation modes:
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.IP \[bu] 2
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default mode is compression;
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.IP \[bu] 2
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\f[B]--decompress\f[R] option activates decompression mode;
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.IP \[bu] 2
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\f[B]--test\f[R] option switches to integrity test mode; this option is
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equivalent to \[lq]\f[B]--decompress --stdout\f[R]\[rq] except that the
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decompressed data is discarded instead of being written to standard
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output.
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.PP
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Every non-option argument is a \f[I]file\f[R] entry.
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If no \f[I]files\f[R] are given or \f[I]file\f[R] is
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\[lq]\f[B]-\f[R]\[rq], \f[B]brotli\f[R] reads from standard input.
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All arguments after \[lq]\f[B]--\f[R]\[rq] are \f[I]file\f[R] entries.
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.PP
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Unless \f[B]--stdout\f[R] or \f[B]--output\f[R] is specified,
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\f[I]files\f[R] are written to a new file whose name is derived from the
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source \f[I]file\f[R] name:
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.IP \[bu] 2
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when compressing, a suffix is appended to the source filename to get the
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target filename
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.IP \[bu] 2
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when decompressing, a suffix is removed from the source filename to get
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the target filename
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.PP
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Default suffix is \f[B].br\f[R], but it could be specified with
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\f[B]--suffix\f[R] option.
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.PP
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Conflicting or duplicate \f[I]options\f[R] are not allowed.
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.SH OPTIONS
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.IP \[bu] 2
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\f[B]-#\f[R]: compression level (0-9); bigger values cause denser, but
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slower compression
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.IP \[bu] 2
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\f[B]-c\f[R], \f[B]--stdout\f[R]: write on standard output
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.IP \[bu] 2
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\f[B]-d\f[R], \f[B]--decompress\f[R]: decompress mode
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.IP \[bu] 2
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\f[B]-f\f[R], \f[B]--force\f[R]: force output file overwrite
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.IP \[bu] 2
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\f[B]-h\f[R], \f[B]--help\f[R]: display this help and exit
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.IP \[bu] 2
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\f[B]-j\f[R], \f[B]--rm\f[R]: remove source file(s); \f[B]gzip
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(1)\f[R]-like behaviour
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.IP \[bu] 2
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\f[B]-k\f[R], \f[B]--keep\f[R]: keep source file(s); \f[B]zstd
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(1)\f[R]-like behaviour
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.IP \[bu] 2
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\f[B]-n\f[R], \f[B]--no-copy-stat\f[R]: do not copy source file(s)
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attributes
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.IP \[bu] 2
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\f[B]-o FILE\f[R], \f[B]--output=FILE\f[R] output file; valid only if
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there is a single input entry
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.IP \[bu] 2
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\f[B]-q NUM\f[R], \f[B]--quality=NUM\f[R]: compression level (0-11);
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bigger values cause denser, but slower compression
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.IP \[bu] 2
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\f[B]-t\f[R], \f[B]--test\f[R]: test file integrity mode
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.IP \[bu] 2
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\f[B]-v\f[R], \f[B]--verbose\f[R]: increase output verbosity
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.IP \[bu] 2
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\f[B]-w NUM\f[R], \f[B]--lgwin=NUM\f[R]: set LZ77 window size (0, 10-24)
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(default: 24); window size is \f[B](pow(2, NUM) - 16)\f[R]; 0 lets
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compressor decide over the optimal value; bigger windows size improve
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density; decoder might require up to window size memory to operate
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.IP \[bu] 2
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\f[B]-C B64\f[R], \f[B]--comment=B64\f[R]: set comment; argument is
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base64-decoded first; when decoding: check stream comment; when
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encoding: embed comment (fingerprint)
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.IP \[bu] 2
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\f[B]-D FILE\f[R], \f[B]--dictionary=FILE\f[R]: use FILE as raw (LZ77)
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dictionary; same dictionary MUST be used both for compression and
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decompression
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.IP \[bu] 2
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\f[B]-K\f[R], \f[B]--concatenated\f[R]: when decoding, allow
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concatenated brotli streams as input
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.IP \[bu] 2
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\f[B]-S SUF\f[R], \f[B]--suffix=SUF\f[R]: output file suffix (default:
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\f[B].br\f[R])
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.IP \[bu] 2
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\f[B]-V\f[R], \f[B]--version\f[R]: display version and exit
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.IP \[bu] 2
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\f[B]-Z\f[R], \f[B]--best\f[R]: use best compression level (default);
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same as \[lq]\f[B]-q 11\f[R]\[rq]
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.SH SEE ALSO
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.PP
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\f[B]brotli\f[R] file format is defined in RFC
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7932 (https://www.ietf.org/rfc/rfc7932.txt).
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.PP
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\f[B]brotli\f[R] is open-sourced under the MIT
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License (https://opensource.org/licenses/MIT).
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.PP
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Mailing list: https://groups.google.com/forum/#!forum/brotli
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.SH BUGS
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.PP
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Report bugs at: https://github.com/google/brotli/issues
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