lrzip - a large-file compression program
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>
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
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
-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.
-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
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.
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
-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
-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.
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.
"make install" or just install lrzip somewhere in your search path.
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.
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
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.
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
If you wish to report a problem or make a suggestion then please email
Con at firstname.lastname@example.org
lrzip is released under the GNU General Public License version 2.
Please see the file COPYING for license details.
December 2009 lrzip(1)