projects / mirror_edk2.git / blame
| Commit | Line | Data |
|---|---|---|
| dd4f667e LG |
1 | brotli(1) -- brotli, unbrotli - compress or decompress files |
| 2 | ================================================================ | |
| 3 | ||
| 4 | SYNOPSIS | |
| 5 | -------- | |
| 6 | ||
| 7 | `brotli` [*OPTION|FILE*]... | |
| 8 | ||
| 9 | `unbrotli` is equivalent to `brotli --decompress` | |
| 10 | ||
| 11 | DESCRIPTION | |
| 12 | ----------- | |
| 13 | `brotli` is a generic-purpose lossless compression algorithm that compresses | |
| 14 | data using a combination of a modern variant of the **LZ77** algorithm, Huffman | |
| 15 | coding and 2-nd order context modeling, with a compression ratio comparable to | |
| 16 | the best currently available general-purpose compression methods. It is similar | |
| 17 | in speed with deflate but offers more dense compression. | |
| 18 | ||
| 19 | `brotli` command line syntax similar to `gzip (1)` and `zstd (1)`. | |
| 20 | Unlike `gzip (1)`, source files are preserved by default. It is possible to | |
| 21 | remove them after processing by using the `--rm` _option_. | |
| 22 | ||
| 23 | Arguments that look like "`--name`" or "`--name=value`" are _options_. Every | |
| 24 | _option_ has a short form "`-x`" or "`-x value`". Multiple short form _options_ | |
| 25 | could be coalesced: | |
| 26 | ||
| 27 | * "`--decompress --stdout --suffix=.b`" works the same as | |
| 28 | * "`-d -s -S .b`" and | |
| 29 | * "`-dsS .b`" | |
| 30 | ||
| 31 | `brotli` has 3 operation modes: | |
| 32 | ||
| 33 | * default mode is compression; | |
| 34 | * `--decompress` option activates decompression mode; | |
| 35 | * `--test` option switches to integrity test mode; this option is equivalent to | |
| 36 | "`--decompress --stdout`" except that the decompressed data is discarded | |
| 37 | instead of being written to standard output. | |
| 38 | ||
| 39 | Every non-option argument is a _file_ entry. If no _files_ are given or _file_ | |
| 40 | is "`-`", `brotli` reads from standard input. All arguments after "`--`" are | |
| 41 | _file_ entries. | |
| 42 | ||
| 43 | Unless `--stdout` or `--output` is specified, _files_ are written to a new file | |
| 44 | whose name is derived from the source _file_ name: | |
| 45 | ||
| 46 | * when compressing, a suffix is appended to the source filename to | |
| 47 | get the target filename | |
| 48 | * when decompressing, a suffix is removed from the source filename to | |
| 49 | get the target filename | |
| 50 | ||
| 51 | Default suffix is `.br`, but it could be specified with `--suffix` option. | |
| 52 | ||
| 53 | Conflicting or duplicate _options_ are not allowed. | |
| 54 | ||
| 55 | OPTIONS | |
| 56 | ------- | |
| 57 | ||
| 58 | * `-#`: | |
| 59 | compression level (0-9); bigger values cause denser, but slower compression | |
| 60 | * `-c`, `--stdout`: | |
| 61 | write on standard output | |
| 62 | * `-d`, `--decompress`: | |
| 63 | decompress mode | |
| 64 | * `-f`, `--force`: | |
| 65 | force output file overwrite | |
| 66 | * `-h`, `--help`: | |
| 67 | display this help and exit | |
| 68 | * `-j`, `--rm`: | |
| 69 | remove source file(s); `gzip (1)`-like behaviour | |
| 70 | * `-k`, `--keep`: | |
| 71 | keep source file(s); `zstd (1)`-like behaviour | |
| 72 | * `-n`, `--no-copy-stat`: | |
| 73 | do not copy source file(s) attributes | |
| 74 | * `-o FILE`, `--output=FILE` | |
| 75 | output file; valid only if there is a single input entry | |
| 76 | * `-q NUM`, `--quality=NUM`: | |
| 77 | compression level (0-11); bigger values cause denser, but slower compression | |
| 78 | * `-t`, `--test`: | |
| 79 | test file integrity mode | |
| 80 | * `-v`, `--verbose`: | |
| 81 | increase output verbosity | |
| 82 | * `-w NUM`, `--lgwin=NUM`: | |
| 83 | set LZ77 window size (0, 10-24) (default: 22); window size is | |
| 84 | `(2**NUM - 16)`; 0 lets compressor decide over the optimal value; bigger | |
| 85 | windows size improve density; decoder might require up to window size | |
| 86 | memory to operate | |
| 87 | * `-S SUF`, `--suffix=SUF`: | |
| 88 | output file suffix (default: `.br`) | |
| 89 | * `-V`, `--version`: | |
| 90 | display version and exit | |
| 91 | * `-Z`, `--best`: | |
| 92 | use best compression level (default); same as "`-q 11`" | |
| 93 | ||
| 94 | SEE ALSO | |
| 95 | -------- | |
| 96 | ||
| 97 | `brotli` file format is defined in | |
| 98 | [RFC 7932](https://www.ietf.org/rfc/rfc7932.txt). | |
| 99 | ||
| 100 | `brotli` is open-sourced under the | |
| 101 | [MIT License](https://opensource.org/licenses/MIT). | |
| 102 | ||
| 103 | Mailing list: https://groups.google.com/forum/#!forum/brotli | |
| 104 | ||
| 105 | BUGS | |
| 106 | ---- | |
| 107 | Report bugs at: https://github.com/google/brotli/issues |