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= 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
               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