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diff --git a/doc/lzop.txt b/doc/lzop.txt new file mode 100644 index 0000000..9e648ed --- /dev/null +++ b/doc/lzop.txt @@ -0,0 +1,423 @@ +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, -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 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. + +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 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. + |