lz4(1)                           User Commands                          lz4(1)












NAME
       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 -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.



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.  lz4
       supports a command line syntax similar to gzip(1).  The native file
       format is the .lz4 format.


   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 extensionq

       -t, --test
              Test the integrity of compressed .lz4 files.  The decompressed
              data is discarded.  No files are created nor removed.

   Operation modifiers
       -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= 64KiB ; B5= 256KiB ; B6= 1MiB ; B7= 4MiB

       -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
               sparse mode support (default:enabled on file, disabled on
              stdout)

       -l
               use Legacy format (useful for Linux Kernel compression)

   Other options
       -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


BUGS
       Report bugs at: https://github.com/Cyan4973/lz4


AUTHOR
       Yann Collet



lz4                               2015-03-21                            lz4(1)