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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] [-qvcfFnNkU] [-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 `-dNp'.
-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.
Commands are listed in increasing priority here, i.e. -t has priority
over -d, -l over -t, and so on.
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, -p*DIR*, --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 (possibly huge) backups.
Requires GNU tar or a compatible version which accpets 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
lzop -d < y.tar.lzo | tar -tvf - -> list a tar file
list
lzop -l < y.lzo
cat y.lzo | lzop -l
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 -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: 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.
SEE ALSO
bzip2(1), gzip(1), tar(1)
Precompiled binaries for some platforms are available from the lzop home
page.
see http://www.oberhumer.com/opensource/lzop/
lzop uses the LZO data compression library for compression services.
see http://www.oberhumer.com/opensource/lzo/
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
effect).
lzop's diagnostics are intended to be self-explanatory.
BUGS
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 by Markus Franz Xaver Johannes Oberhumer.
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 check the GNU GPL FAQ at
http://www.gnu.org/licenses/gpl-faq.html about possible implications.