lz4, unlz4, lz4cat - Compress or decompress .lz4 files
- lz4 [OPTIONS] [-|INPUT-FILE] <OUTPUT-FILE>
unlz4 is equivalent to lz4 -d
lz4cat is equivalent to lz4 -dc
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.
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. lz4
supports a command line syntax similar to gzip(1). The native file
format is the .lz4 format.
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
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.
When multiple contradictory commands are issued on a same command line, only the
latest one will be applied.
- -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 extensionq
- -t, --test
- Test the integrity of compressed .lz4 files. The decompressed data
is discarded. No files are created nor removed.
- -1
-
fast compression (default)
- -9
-
high compression
- -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 output filename for the
compressed file.
With -m , you can specify any number of input filenames. Each of
them will be compressed independently, and the resulting name of the
compressed file will be filename.lz4
- -B#
-
block size [4-7](default : 7)
B4= 64KB ; B5= 256KB ; B6= 1MB ; B7= 4MB
- -BD
-
block dependency (improve compression ratio)
- --[no-]frame-crc
-
select frame checksum (default:enabled)
- --[no-]content-size
-
header includes original size (default:not present)
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
-
enable sparse file (default:disabled)(experimental)
- -l
-
use Legacy format (useful for Linux Kernel compression)
- -v, --verbose
-
verbose mode
- -q, --quiet
-
suppress warnings; specify twice to suppress errors too
- -h/-H
-
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/xz.
- -b
-
benchmark file(s)
- -i#
-
iteration loops [1-9](default : 3), benchmark mode only
Report bugs at: https://github.com/Cyan4973/lz4