brotli(1) User Manual brotli(1)

# [NAME](#NAME)

[brotli(1)](/man/os/brotli/brotli.1) -- brotli, brcat, unbrotli - compress or decompress files

# [SYNOPSIS](#SYNOPSIS)

**brotli** \[*OPTION|FILE*]...

**brcat** is equivalent to **brotli --decompress --concatenated** **--stdout**

**unbrotli** is equivalent to **brotli --decompress**

# [DESCRIPTION](#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)**](/man/os/brotli/gzip.1) and [**zstd (1)**](/man/os/brotli/zstd.1). Unlike [**gzip (1)**](/man/os/brotli/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:

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“**--decompress --stdout --suffix=.b**” works the same as

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“**-d -s -S .b**” and

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“**-dsS .b**”

**brotli** has 3 operation modes:

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default mode is compression;

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**--decompress** option activates decompression mode;

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**--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:

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

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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](#OPTIONS)

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

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**-c**, **--stdout**: write on standard output

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**-d**, **--decompress**: decompress mode

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**-f**, **--force**: force output file overwrite

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**-h**, **--help**: display this help and exit

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**-j**, **--rm**: remove source file(s); **gzip** **(1)**-like behaviour

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**-k**, **--keep**: keep source file(s); **zstd** **(1)**-like behaviour

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**-n**, **--no-copy-stat**: do not copy source file(s) attributes

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**-o FILE**, **--output=FILE** output file; valid only if there is a single input entry

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**-q NUM**, **--quality=NUM**: compression level (0-11); bigger values cause denser, but slower compression

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**-t**, **--test**: test file integrity mode

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**-v**, **--verbose**: increase output verbosity

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**-w NUM**, **--lgwin=NUM**: set LZ77 window size (0, 10-24) (default: 24); window size is **(pow(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

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**-C B64**, **--comment=B64**: set comment; argument is base64-decoded first; when decoding: check stream comment; when encoding: embed comment (fingerprint)

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**-D FILE**, **--dictionary=FILE**: use FILE as raw (LZ77) dictionary; same dictionary MUST be used both for compression and decompression

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**-K**, **--concatenated**: when decoding, allow concatenated brotli streams as input

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**-S SUF**, **--suffix=SUF**: output file suffix (default: **.br**)

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**-V**, **--version**: display version and exit

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**-Z**, **--best**: use best compression level (default); same as “**-q 11**”

# [SEE ALSO](#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](#BUGS)

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

August 14 2021 brotli 1.0.9

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Document: brotli(1) from brotli 1.2.1-r0 (Chainguard OS)
Source: https://github.com/google/brotli.git