Provided by: lrzip_0.44-1_i386 bug

NAME

       lrzip - a large-file compression program

SYNOPSIS

       lrzip [OPTIONS] <file>
       lrzip -d [OPTIONS] <file>
       lrunzip [OPTIONS] <file>
       lrztar [lrzip options] <directory>
       lrztar -d [lrzip options] <directory>
       LRZIP=NOCONFIG [lrzip|lrunzip] [OPTIONS] <file>

DESCRIPTION

       LRZIP is a file compression program designed to do particularly well on
       very large files containing long  distance  redundancy.   lrztar  is  a
       wrapper   for  LRZIP  to  simplify  compression  and  decompression  of
       directories.

OPTIONS SUMMARY

       Here is a summary of the options to lrzip.

         -w size       compression window in hundreds of MB
                       default chosen by heuristic dependent on ram and chosen compression
         -d            decompress
         -o filename   specify the output file name and/or path
         -O directory  specify the output directory when -o is not used
         -S suffix     specify compressed suffix (default ’.lrz’)
         -f            force overwrite of any existing files
         -D            delete existing files
         -P            don’t set permissions on output file. It may leave it world-readable
         -q            don’t show compression progress
         -L level      set lzma/bzip2/gzip compression level (1-9, default 7)
         -n            no backend compression. Prepare for other compressor
         -l            lzo compression (ultra fast)
         -b            bzip2 compression
         -g            gzip compression using zlib
         -z            zpaq compression (best, extreme compression, extremely slow)
         -M            Maximum window and level - (all available ram and level 9)
         -T value      Compression threshold with LZO test. (0 (nil) - 10 (high), default 1)
         -N value      Set nice value to value (default 19)
         -v[v]         Increase verbosity
         -V            show version
         -t            test compressed file integrity
         -i            show compressed file information

       If no filenames or "-" is specified, stdin/out will be used.

OPTIONS

       -h     Print an options summary page

       -V     Print the lrzip version number

       -v[v]  Increases verbosity. -vv will print more messages than -v.

       -w n   Set the compression window size to n in hundreds  of  megabytes.
              This  is the amount of memory lrzip will search during its first
              stage of  pre-compression  and  is  the  main  thing  that  will
              determine  how  much  benefit  lrzip  will provide over ordinary
              compression with the 2nd stage algorithm. Because of buffers and
              compression  overheads,  the  value chosen must be significantly
              smaller than your available ram or lrzip will induce  a  massive
              swap  load.  If  not set (recommended), the value chosen will be
              determined by internal heuristic in lrzip which  uses  the  most
              memory  that  is  reasonable.  It  is  limited  to  2GB on 32bit
              machines.

       -L 1..9
              Set the compression level from 1 to 9. The  default  is  to  use
              level  7,  which  is  a  reasonable compromise between speed and
              compression. The compression level is also strongly  related  to
              how much memory lrzip uses. See the -w option for details.

       -M     Maximum  compression.  If this option is set, then lrzip ignores
              the heuristic mentioned for the default window and tries to  set
              it  to  all  available  ram,  and  sets the compression level to
              maximum. This  will  cause  a  significant  swap  load  on  most
              machines, and may even fail without enough swap space allocated.
              Be prepared to walk away if you  use  this  option.  It  is  not
              recommended  to use this as it hardly ever improves compression.

       -T 0..10
              Sets the LZO compression threshold when  testing  a  data  chunk
              when slower compression is used. The threshold level can be from
              0 to 10.  This  option  is  used  to  speed  up  compression  by
              avoiding  doing the slow compression pass. The reasoning is that
              if it is completely incompressible by LZO then it will  also  be
              incompressible  by them, thereby saving time.  The default is 1.

       -d     Decompress. If this option is not used then lrzip looks  at  the
              name  used  to  launch  the  program.  If it contains the string
              "lrunzip" then the -d option is automatically set.

       -l     LZO Compression. If this option is set then lrzip will  use  the
              ultra  fast  lzo  compression  algorithm for the 2nd stage. This
              mode of compression gives bzip2 like compression at the speed it
              would  normally  take  to simply copy the file, giving excellent
              compression/time value]&.

       -n     No 2nd stage compression. If this option is set then lrzip  will
              only perform the long distance redundancy 1st stage compression.
              While this does not compress any faster than LZO compression, it
              produces  a  smaller  file  that then responds better to further
              compression (by  eg  another  application),  also  reducing  the
              compression time substantially.

       -b     Bzip2  compression.  Uses  bzip2  compression for the 2nd stage,
              much like the original rzip does.

       -g     Gzip compression. Uses gzip compression for the 2nd stage,  much
              like  the  original rzip does. Uses libz compress and uncompress
              functions.

       -z     ZPAQ compression. Uses ZPAQ compression which is  from  the  PAQ
              family  of  compressors  known  for  having  some of the highest
              compression ratios possible but at the cost of  being  extremely
              slow on both compress and decompress.

       -o     Set  the  output  file  name. If this option is not set then the
              output file name is chosen based  on  the  input  name  and  the
              suffix.  The -o option cannot be used if more than one file name
              is specified on the command line.

       -O     Set the output directory for the default filename.  This  option
              cannot be combined with -o.

       -S     Set the compression suffix. The default is ’.lrz’.

       -f     If  this  option  is not specified (Default) then lrzip will not
              overwrite any existing files. If you set this option  then  rzip
              will silently overwrite any files as needed.

       -D     If  this  option  is specified then lrzip will delete the source
              file after successful compression or  decompression.  When  this
              option is not specified then the source files are not deleted.

       -P     If  this  option is specified then lrzip will not try to set the
              file permissions on writing the file. This helps when writing to
              a brain damaged filesystem like fat32 on windows.

       -q     If  this  option  is  specified  then  lrzip  will  not show the
              percentage progress while  compressing.  Note  that  compression
              happens  in  bursts  with  lzma compression which is the default
              compression. This means that it will progress very  rapidly  for
              short periods and then stop for long periods.

       -N value
              The default nice value is 19. This option can be used to set the
              priority scheduling for the lrzip backup or decompression. Valid
              nice values are from -20 to 19.

       -t     This  tests  the  compressed  file  integrity.  It  does this by
              decompressing it to a temporary file and then deleting it.

       -i     This shows information about a compressed  file.  It  shows  the
              compressed  size,  the  decompressed size, the compression ratio
              and what compression was used.  Note that the  compression  mode
              is  detected  from  the  first  block  only  and it will show no
              compression used if the first block was incompressible, even  if
              later blocks were compressible.

INSTALLATION

       "make install" or just install lrzip somewhere in your search path.

COMPRESSION ALGORITHM

       LRZIP  operates  in two stages. The first stage finds and encodes large
       chunks of duplicated data over potentially very long distances (limited
       only  by  your available ram) in the input file. The second stage is to
       use a compression algorithm to compress the output of the first  stage.
       The  compression algorithm can be chosen to be optimised for size (lzma
       - default), speed (lzo), legacy (bzip2) or (gzip)  or  can  be  omitted
       entirely  doing  only the first stage. A one stage only compressed file
       can almost always improve both the compression size and speed done by a
       subsequent compression program.

       The  key  difference  between  lrzip  and  other well known compression
       algorithms is its ability to  take  advantage  of  very  long  distance
       redundancy.  The  well  known  deflate  algorithm  used  in gzip uses a
       maximum history buffer of 32k. The  block  sorting  algorithm  used  in
       bzip2 is limited to 900k of history. The history buffer in lrzip can be
       any size long, limited only by available ram.

       It is quite common these days to need to compress  files  that  contain
       long distance redundancies. For example, when compressing a set of home
       directories several users might have copies of the  same  file,  or  of
       quite  similar  files.  It  is  also  common to have a single file that
       contains large duplicated chunks over long distances, such as pdf files
       containing repeated copies of the same image. Most compression programs
       won’t be able to take advantage of  this  redundancy,  and  thus  might
       achieve a much lower compression ratio than lrzip can achieve.

FILES

       LRZIP  now  recognizes  a  configuration  file  that  contains  default
       settings.  This configuration is searched for in the current directory,
       /etc/lrzip,  and  $HOME/.lrzip.  The  configuration  filename  must  be
       lrzip.conf.

ENVIRONMENT

       By default, lrzip  will  search  for  and  use  a  configuration  file,
       lrzip.conf.   If  the  user  wishes  to  bypass the file, a startup ENV
       variable may be set.
       LRZIP = NOCONFIG [lrzip|lrunzip] [OPTIONS] <file>
       which will force lrzip to ignore the configuration file.

HISTORY - Notes on rzip by Andrew Tridgell

       The ideas behind rzip were  first  implemented  in  1998  while  I  was
       working  on  rsync.  That version was too slow to be practical, and was
       replaced by this version in 2003.  LRZIP was created by the  desire  to
       have  better  compression  and/or  speed by Con Kolivas on blending the
       lzma and lzo compression algorithms with  the  rzip  first  stage,  and
       extending the compression windows to scale with increasing ram sizes.

BUGS

       Probably lots.

SEE ALSO

       lrzip.conf(5)

AUTHOR and CREDITS

       rzip was written by Andrew Tridgell.
       lzma was written by Igor Pavlov.
       lzo was written by Markus Oberhumer.
       zpaq was written by Matt Mahoney.
       lrzip was bastardised from rzip by Con Kolivas.
       Peter  Hyman  added  informational  output,  updated LZMA SDK, and aded
       multi-threading capabilities.

       If you wish to report a problem or make a suggestion then please  email
       Con at kernel@kolivas.org

       lrzip  is  released  under  the  GNU  General Public License version 2.
       Please see the file COPYING for license details.

                                 December 2009                        lrzip(1)