Add "man" target to Makefile

- `make man` makes manpage lz4.1 from lz4.1.md
- It needs `gem` and `ronn` which is same as xxhash.1.md is required.

1 files changed, 206 insertions, 0 deletions

diff --git a/programs/lz4.1.md b/programs/lz4.1.md
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+lz4(1) -- lz4, unlz4, lz4cat - Compress or decompress .lz4 files
+================================================================
+
+SYNOPSIS
+--------
+
+`lz4` [*OPTIONS*] [-|INPUT-FILE] <OUTPUT-FILE>
+
+`unlz4` is equivalent to `lz4 -d`
+
+`lz4cat` is equivalent to `lz4 -dcfm`
+
+When writing scripts that need to decompress files,
+it is recommended to always use the name `lz4` with appropriate arguments
+(`lz4 -d` or `lz4 -dc`) instead of the names `unlz4` and `lz4cat`.
+
+
+DESCRIPTION
+-----------
+
+`lz4` is an extremely fast lossless compression algorithm,
+based on **byte-aligned LZ77** family of compression scheme.
+`lz4` offers compression speeds of 400 MB/s per core, linearly scalable with
+multi-core CPUs.
+It features an extremely fast decoder, with speed in multiple GB/s per core,
+typically reaching RAM speed limit on multi-core systems.
+The native file format is the `.lz4` format.
+
+### Difference between lz4 and gzip
+
+`lz4` supports a command line syntax similar
+_but not identical_ to `gzip(1)`.
+Differences are :
+
+  * `lz4` preserves original files
+  * `lz4` compresses a single file by default (use `-m` for multiple files)
+  * `lz4 file1 file2` means : compress file1 _into_ file2
+  * When no destination name is provided, compressed file name receives
+    a `.lz4` suffix
+  * When no destination name is provided, if `stdout` is _not_ the console,
+    it becomes the output (like a silent `-c`).
+    Therefore `lz4 file > /dev/null` will not create `file.lz4`
+  * `lz4 file` shows real-time statistics during compression
+    (use `-q` to silent them)
+
+Default behaviors can be modified by opt-in commands, described below.
+`lz4 --quiet --multiple` more closely mimics `gzip` behavior.
+
+### Concatenation of .lz4 files
+
+It is possible to concatenate `.lz4` files as is.
+`lz4` will decompress such files as if they were a single `.lz4` file.
+For example:
+    lz4 file1  > foo.lz4
+    lz4 file2 >> foo.lz4
+
+then
+    lz4cat foo.lz4
+
+is equivalent to :
+    cat file1 file2
+
+
+OPTIONS
+-------
+
+### Short commands concatenation
+
+In some cases, some options can be expressed using short command `-x`
+or long command `--long-word`.
+Short commands can be concatenated together.
+For example, `-d -c` is equivalent to `-dc`.
+Long commands cannot be concatenated.
+They must be clearly separated by a space.
+
+### Multiple commands
+
+When multiple contradictory commands are issued on a same command line,
+only the latest one will be applied.
+
+### Operation mode
+
+* `-z` `--compress`:
+  Compress.
+  This is the default operation mode when no operation mode option is
+  specified, no other operation mode is implied from the command name
+  (for example, `unlz4` implies `--decompress`),
+  nor from the input file name
+  (for example, a file extension `.lz4` implies  `--decompress` by default).
+  `-z` can also be used to force compression of an already compressed
+  `.lz4` file.
+
+* `-d` `--decompress` `--uncompress`:
+  Decompress.
+  `--decompress` is also the default operation when the input filename has an
+  `.lz4` extension.
+
+* `-t` `--test`:
+  Test the integrity of compressed `.lz4` files.
+  The decompressed data is discarded.
+  No files are created nor removed.
+
+* `-b#`:
+  Benchmark mode, using `#` compression level.
+
+### Operation modifiers
+
+* `-#`:
+  Compression level, with # being any value from 1 to 16.
+  Higher values trade compression speed for compression ratio.
+  Values above 16 are considered the same as 16.
+  Recommended values are 1 for fast compression (default),
+  and 9 for high compression.
+  Speed/compression trade-off will vary depending on data to compress.
+  Decompression speed remains fast at all settings.
+
+* `-f` `--[no-]force`:
+  This option has several effects:
+
+  If the target file already exists, overwrite it without prompting.
+
+  When used with `--decompress` and `lz4` cannot recognize the type of
+  the source file, copy the source file as is to standard output.
+  This allows `lz4cat --force` to be used like `cat (1)` for files
+  that have not been compressed with `lz4`.
+
+* `-c` `--stdout` `--to-stdout`:
+  Force write to standard output, even if it is the console.
+
+* `-m` `--multiple`:
+  Multiple file names.
+  By default, the second filename is used as the destination filename
+  for the compressed file.
+  With `-m`, it is possible to specify any number of input filenames.
+  Each of them will be compressed independently, and the resulting name of
+  each compressed file will be `filename.lz4`.
+
+* `-B#`:
+  Block size \[4-7\](default : 7)<br/>
+  `-B4`= 64KB ; `-B5`= 256KB ; `-B6`= 1MB ; `-B7`= 4MB
+
+* `-BD`:
+  Block dependency (improves compression ratio on small blocks)
+
+* `--[no-]frame-crc`:
+  Select frame checksum (default:enabled)
+
+* `--[no-]content-size`:
+  Header includes original size (default:not present)<br/>
+  Note : this option can only be activated when the original size can be
+  determined, hence for a file. It won't work with unknown source size,
+  such as stdin or pipe.
+
+* `--[no-]sparse`:
+  Sparse mode support (default:enabled on file, disabled on stdout)
+
+* `-l`:
+  Use Legacy format (typically used for Linux Kernel compression)<br/>
+  Note : `-l` is not compatible with `-m` (`--multiple`)
+
+### Other options
+
+* `-v` `--verbose`:
+  Verbose mode
+
+* `-q` `--quiet`:
+  Suppress warnings and real-time statistics; specify twice to suppress
+  errors too
+
+* `-h` `-H` `--help`:
+  Display help/long help and exit
+
+* `-V` `--version`:
+  Display Version number and exit
+
+* `-k` `--keep`:
+  Don't delete source file.
+  This is default behavior anyway, so this option is just for compatibility
+  with `gzip(1)` / `xz(1)`.
+
+
+### Benchmark mode
+
+* `-b#`:
+  Benchmark file(s), using # compression level
+
+* `-e#`:
+  Benchmark multiple compression levels, from b# to e# (included)
+
+* `-i#`:
+  Minimum evaluation in seconds \[1-9\] (default : 3)
+
+* `-r`:
+  Operate recursively on directories
+
+
+BUGS
+----
+
+Report bugs at: https://github.com/lz4/lz4/issues
+
+
+AUTHOR
+------
+
+Yann Collet