Ubuntu Manpage: lzop - compress or expand files

NAME

       lzop - compress or expand files

ABSTRACT

       lzop is a file compressor very similar to gzip.  lzop favors speed over compression ratio.

SYNOPSIS

       lzop [ command ] [ options ] [ filename ...  ]

       lzop [-dxlthIVL19] [-qvcfFnNPkU] [-o file] [-p[path]] [-S suffix] [filename ...]

DESCRIPTION

lzop reduces the size of the named files. Whenever possible, each file is compressed into
one with the extension .lzo, while keeping the same ownership modes, access and
modification times. If no files are specified, or if a file name is "-", lzop tries to
compress the standard input to the standard output. lzop will only attempt to compress
regular files or symbolic links to regular files. In particular, it will ignore
directories.

If the compressed file name is too long for its file system, lzop truncates it.

Compressed files can be restored to their original form using lzop -d. lzop -d takes a
list of files on its command line and decompresses each file whose name ends with .lzo and
which begins with the correct magic number to an uncompressed file without the original
extension. lzop -d also recognizes the special extension .tzo as shorthand for .tar.lzo.
When compressing, lzop uses the .tzo extension if necessary instead of truncating a file
with a .tar extension.

lzop stores the original file name, mode and time stamp in the compressed file. These can
be used when decompressing the file with the -d option. This is useful when the compressed
file name was truncated or when the time stamp was not preserved after a file transfer.

lzop preserves the ownership, mode and time stamp of files when compressing. When
decompressing lzop restores the mode and time stamp if present in the compressed files.
See the options -n, -N, --no-mode and --no-time for more information.

lzop always keeps original files unchanged unless you use the option -U.

lzop uses the LZO data compression library for compression services. The amount of
compression obtained depends on the size of the input and the distribution of common
substrings. Typically, text such as source code or English is compressed into 40-50% of
the original size, and large files usually compress much better than small ones.
Compression and decompression speed is generally much faster than that achieved by gzip,
but compression ratio is worse.

COMPRESSION LEVELS
lzop offers the following compression levels of the LZO1X algorithm:

-3 the default level offers pretty fast compression. -2, -3, -4, -5 and -6 are currently
all equivalent - this may change in a future release.

-1, --fast
can be even a little bit faster in some cases - but most times you won't notice the
difference

-7, -8, -9, --best
these compression levels are mainly intended for generating pre-compressed data -
especially -9 can be somewhat slow

Decompression is very fast for all compression levels, and decompression speed is not
affected by the compression level.

MAIN COMMAND

If no other command is given then lzop defaults to compression (using compression level
-3).

-#, --fast, --best
Regulate the speed of compression using the specified digit #, where -1 or --fast
indicates the fastest compression method (less compression) and -9 or --best indicates
the slowest compression method (best compression). The default compression level is
-3.

-d, --decompress, --uncompress
Decompress. Each file will be placed into same the directory as the compressed file.

-x, --extract
Extract compressed files to the current working directory. This is the same as '-dPp'.

-t, --test
Test. Check the compressed file integrity.

-l, --list
For each compressed file, list the following fields:

method: compression method
compressed: size of the compressed file
uncompr.: size of the uncompressed file
ratio: compression ratio
uncompressed_name: name of the uncompressed file

In combination with the --verbose option, the following fields are also displayed:

date & time: time stamp for the uncompressed file

With --name, the uncompressed name, date and time are those stored within the compress
file if present.

With --verbose, the size totals and compression ratio for all files is also displayed.
With --quiet, the title and totals lines are not displayed.

Note that lzop defines compression ratio as compressed_size / uncompressed_size.

--ls, --ls=FLAGS
List each compressed file in a format similar to ls -ln.

The following flags are currently honoured:
F Append a '*' for executable files.
G Inhibit display of group information.
Q Enclose file names in double quotes.

--info
For each compressed file, list the internal header fields.

-I, --sysinfo
Display information about the system and quit.

-L, --license
Display the lzop license and quit.

-h, -H, --help
Display a help screen and quit.

-V Version. Display the version number and compilation options and quit.

--version
Version. Display the version number and quit.

OPTIONS

-c, --stdout, --to-stdout
Write output on standard output. If there are several input files, the output consists
of a sequence of independently (de)compressed members. To obtain better compression,
concatenate all input files before compressing them.

-o FILE, --output=FILE
Write output to the file FILE. If there are several input files, the output consists
of a sequence of independently (de)compressed members.

-p, -pDIR, --path=DIR
Write output files into the directory DIR instead of the directory determined by the
input file. If DIR is omitted, then write to the current working directory.

-f, --force
Force lzop to

- overwrite existing files
- (de-)compress from stdin even if it seems a terminal
- (de-)compress to stdout even if it seems a terminal
- allow option -c in combination with -U

Using -f two or more times forces things like

- compress files that already have a .lzo suffix
- try to decompress files that do not have a valid suffix
- try to handle compressed files with unknown header flags

Use with care.

-F, --no-checksum
Do not store or verify a checksum of the uncompressed file when compressing or
decompressing. This speeds up the operation of lzop a little bit (especially when
decompressing), but as unnoticed data corruption can happen in case of damaged
compressed files the usage of this option is not generally recommended. Also, a
checksum is always stored when compressing with one of the slow compression levels
(-7, -8 or -9), regardless of this option.

-n, --no-name
When decompressing, do not restore the original file name if present (remove only the
lzop suffix from the compressed file name). This option is the default under UNIX.

-N, --name
When decompressing, restore the original file name if present. This option is useful
on systems which have a limit on file name length. If the original name saved in the
compressed file is not suitable for its file system, a new name is constructed from
the original one to make it legal. This option is the default under DOS, Windows and
OS/2.

-P When decompressing, restore the original path and file name if present. When
compressing, store the relative (and cleaned) path name. This option is mainly useful
when using archive mode - see usage examples below.

--no-mode
When decompressing, do not restore the original mode (permissions) saved in the
compressed file.

--no-time
When decompressing, do not restore the original time stamp saved in the compressed
file.

-S .suf, --suffix=.suf
Use suffix .suf instead of .lzo. The suffix must not contain multiple dots and special
characters like '+' or '*', and suffixes other than .lzo should be avoided to avoid
confusion when files are transferred to other systems.

-k, --keep
Do not delete input files. This is the default.

-U, --unlink, --delete
Delete input files after succesfull compression or decompression. Use this option to
make lzop behave like gzip and bzip2. Note that explicitly giving -k overrides -U.

--crc32
Use a crc32 checksum instead of a adler32 checksum.

--no-warn
Suppress all warnings.

--ignore-warn
Suppress all warnings, and never exit with exit status 2.

-q, --quiet, --silent
Suppress all warnings and decrease the verbosity of some commands like --list or
--test.

-v, --verbose
Verbose. Display the name for each file compressed or decompressed. Multiple -v can be
used to increase the verbosity of some commands like --list or --test.

-- Specifies that this is the end of the options. Any file name after -- will not be
interpreted as an option even if it starts with a hyphen.

OTHER OPTIONS

--no-stdin
Do not try to read standard input (but a file name "-" will still override this
option). In old versions of lzop, this option was necessary when used in cron jobs
(which do not have a controlling terminal).

--filter=NUMBER
Rarely useful. Preprocess data with a special "multimedia" filter before compressing
in order to improve compression ratio. NUMBER must be a decimal number from 1 to 16,
inclusive. Using a filter slows down both compression and decompression quite a bit,
and the compression ratio usually doesn't improve much either... More effective
filters may be added in the future, though.

You can try --filter=1 with data like 8-bit sound samples, --filter=2 with 16-bit
samples or depth-16 images, etc.

Un-filtering during decompression is handled automatically.

-C, --checksum
Deprecated. Only for compatibility with very old versions as lzop now uses a checksum
by default. This option will get removed in a future release.

--no-color
Do not use any color escape sequences.

--mono
Assume a mono ANSI terminal. This is the default under UNIX (if console support is
compiled in).

--color
Assume a color ANSI terminal or try full-screen access. This is the default under DOS
and in a Linux virtual console (if console support is compiled in).

ADVANCED USAGE

       lzop allows you to deal with your files in many flexible ways. Here are some usage
       examples:

       backup mode
          tar --use-compress-program=lzop -cf archive.tar.lzo files..

          This is the recommended mode for creating backups.
          Requires GNU tar or a compatible version which accepts the
          '--use-compress-program=XXX' option.

       single file mode: individually (de)compress each file
         create
           lzop a.c             -> create a.c.lzo
           lzop a.c b.c         -> create a.c.lzo & b.c.lzo
           lzop -U a.c b.c      -> create a.c.lzo & b.c.lzo and delete a.c & b.c
           lzop *.c

         extract
           lzop -d a.c.lzo      -> restore a.c
           lzop -df a.c.lzo     -> restore a.c, overwrite if already exists
           lzop -d *.lzo

         list
           lzop -l a.c.lzo
           lzop -l *.lzo
           lzop -lv *.lzo       -> be verbose

         test
           lzop -t a.c.lzo
           lzop -tq *.lzo       -> be quiet

       pipe mode: (de)compress from stdin to stdout
         create
           lzop < a.c > y.lzo
           cat a.c | lzop > y.lzo
           tar -cf - *.c | lzop > y.tar.lzo     -> create a compressed tar file

         extract
           lzop -d < y.lzo > a.c
           lzop -d < y.tar.lzo | tar -xvf -     -> extract a tar file

         list
           lzop -l < y.lzo
           cat y.lzo | lzop -l
           lzop -d < y.tar.lzo | tar -tvf -     -> list a tar file

         test
           lzop -t < y.lzo
           cat y.lzo | lzop -t

       stdout mode: (de)compress to stdout
         create
           lzop -c a.c > y.lzo

         extract
           lzop -dc y.lzo > a.c
           lzop -dc y.tar.lzo | tar -xvf -      -> extract a tar file

         list
           lzop -dc y.tar.lzo | tar -tvf -      -> list a tar file

       archive mode: compress/extract multiple files into a single archive file
         create
           lzop a.c b.c -o sources.lzo          -> create an archive
           lzop -P src/*.c -o sources.lzo       -> create an archive, store path name
           lzop -c *.c > sources.lzo            -> another way to create an archive
           lzop -c *.h >> sources.lzo           -> add files to archive

         extract
           lzop -dN sources.lzo
           lzop -x ../src/sources.lzo           -> extract to current directory
           lzop -x -p/tmp < ../src/sources.lzo  -> extract to /tmp directory

         list
           lzop -lNv sources.lzo

         test
           lzop -t sources.lzo
           lzop -tvv sources.lzo                -> be very verbose

       If you wish to create a single archive file with multiple members so that members can
       later be extracted independently, you should prefer a full-featured archiver such as tar.
       The latest version of GNU tar supports the --use-compress-program=lzop option to invoke
       lzop transparently.  lzop is designed as a complement to tar, not as a replacement.

ENVIRONMENT

       The environment variable LZOP can hold a set of default options for lzop. These options
       are interpreted first and can be overwritten by explicit command line parameters.  For
       example:

           for sh/ksh/zsh:    LZOP="-1v --name"; export LZOP
           for csh/tcsh:      setenv LZOP "-1v --name"
           for DOS/Windows:   set LZOP=-1v --name

       On Vax/VMS, the name of the environment variable is LZOP_OPT, to avoid a conflict with the
       symbol set for invocation of the program.

       Not all of the options are valid in the environment variable - lzop will tell you.

DIAGNOSTICS

       Exit status is normally 0; if an error occurs, exit status is 1. If a warning occurs, exit
       status is 2 (unless option --ignore-warn is in effect).

       lzop's diagnostics are intended to be self-explanatory.

BUGS

       No bugs are known. Please report all problems immediately to the author.

AUTHOR

       Markus Franz Xaver Johannes Oberhumer <markus@oberhumer.com>
       http://www.oberhumer.com/opensource/lzop/

COPYRIGHT

       lzop and the LZO library are Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
       2004, 2005, 2006, 2007, 2008, 2009, 2010 by Markus Franz Xaver Johannes Oberhumer.  All
       Rights Reserved.

       lzop and the LZO library are distributed under the terms of the GNU General Public License
       (GPL).

       Legal info: If want to integrate lzop into your commercial (backup-)system please
       carefully read the GNU GPL FAQ at http://www.gnu.org/licenses/gpl-faq.html about possible
       implications.