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       zpaq - PAQ open standard maximum compressor


         create : zpaq [opnsitqv]c<config>[,N...] archive.zpaq file [file ...]
         append : zpaq [opnsitqv]a<config>[,N...] archive.zpaq file [file ...]
         list   : zpaq l archive.zpaq
         extract: zpaq [opntq]x[N] archive.zpaq
         debug  : zpaq [pthv]rF[,N...] [args...]


       PAQ is a series of open source data compression archivers that have
       evolved through collaborative development to top rankings on several
       benchmarks measuring compression ratio although at the expense of speed
       and memory usage.

       Zpaq ia a proposed standard format for highly compressed data that
       allows new compression algorithms to be developed without breaking
       compatibility with older programs. Zpaq is based on PAQ-like context
       mixing algorithms which are top ranked on many benchmarks. The format
       supports archivers, single file compressors, and memory to memory

       ZPAQ is a configurable file compressor and archiver. Its goal is a high
       compression ratio in an open format without loss of compatibility
       between versions as advanced compression techniques are discovered.

       Compression uses by default built-in configuration files. Three
       examples are supplied:

         min.cfg - Fast, minimal compression (LZP + order 3). Requires 4 MB memory.
         mid.cfg - Average compression and speed. Requires 111 MB.
         max.cfg - Slow but good compression. Requires 278 MB.

       The config file is not needed to extract.

       NOTE: in extract mode, if the FILES are listed the files are renamed
       during written out.

       head2 Commands

       a   Append to archive.

       c   Create archive.

       i   Don't store file sizes as comments (saves a few bytes). Normally
           the input file size is stored as a decimal string, taking a few
           bytes. The comment field has no effect on the program except that
           it is displayed by the l and x commands.

       l   List contents of archive.

       n   In create mode: Don't store filenames (names will be needed to
           decompress). In extract mode: decompress all to one file. The
           effect is to require that filenames be given during decompression.

           During extract ignore all stored filenames and append all output to
           one file, the first file in [files...].

       o   Optimize (run faster). You need a C++ compiler installed to use
           this option. If not, drop the "o". You can still use zpaq but it
           will take about twice as long to run.

           If successful, compression is typically 50% to 100% faster. Zpaq
           will look for a program named "zpaq_X" in the temporary directory,
           where X is derived from the SHA1 checksum of the block header
           produced by config file CONFIG with arguments N. If the program
           exists, then Zpaq will call it with the same arguments to perform
           the compression.  If it does not exist then Zpaq will create a
           source code file "zpaq_X.cpp" in the temporary directory, compile
           it, and link it to "zpaq.cpp" or "zpaq.o" depending on the

           The temporary directory is specified by the environment variable
           TEMP if it exists, or else the current directory.

           The program "zpaq_X" will compress its input in the same format as
           described by CONFIG, but faster. If CONFIG specifies a
           preprocessor, then "zpaq_X" will expect to find it too. It will
           also decompress archive blocks in the same configuration but fail
           if it attempts to decompress blocks in any other configuration.

           Program "zpaq_X" will accept the c, a and x commands with all of
           the same modifiers, but will ignore the v and o modifiers and
           ignore any CONFIG file and arguments passed to it. It will not
           accept the l or r commands. Extraction requires a block number
           ("x1", "x2", etc). A different optimized program is used to extract
           each block.

           Zpaq will call the external program "zpaqmake" to compile
           "zpaq_X.cpp", passing it "zpaq_X" as an argument. Normally this
           will be a script that calls a C++ compiler to produce "zpaq_X.o",
           links to "zpaq.o" and outputs "zpaq_X". The script could link to
           "zpaq.cpp" instead of "zpaq.o".

       p   In create mode: Store filename paths in archive. The default is to
           store the name without the path. For example:

               zpaq pc<CONFIG> books.zpaq dir/file

           will store the name as "dir/file". If the p option is also given
           during extraction, then ZPAQ will attempt to extract "file" to the
           subdirectory instead of the current directory. This will fail if
           directory does not exist. ZPAQ does not create directories as

           In extract mode: extract to stored paths instead of current

           The default is to extract to the current directory regardless of
           how the file names are stored. Stored paths must be relative to the
           current directory, not start with a "/", "\", a drive letter like
           "C:" or contain "../" or "..\". If extracting to a subdirectory, it
           must already exist. It will not be created.

           [files...] overrides and has no restrictions on file names. Each
           segment extracts to a different file. If any segments do not have a
           stored filename then they can only be extracted using the p or n

       q   Quiet mode. Don't display compression progress on the screen.

       s   Don't store SHA1 checksums (saves 20 bytes).The decompressor will
           not check that the output is identical to the original input.

       t   In create mode: Append locator tag to non-ZPAQ data.

           Append a locator tag to non-ZPAQ data. The tag is a string of 13
           bytes that allows ZPAQ and UNZPAQ to find the start of a sequence
           of ZPAQ blocks embedded in other data. Program "zpaqsfx" already
           has this tag at the end. However, if a new stub is compiled from
           the source then the t command should be used when appending the
           first file.

           In extract mode: don't post-process (for debugging). Expect
           checksum errors.

       v   Verbose mode. Show CONFIG file as it compiles. This is useful for
           error checking.

       x   Extract. Use "ox" to extract fast. You can extract more slowly with
           plain "x" if you don't have C++ installed. Output files are renamed
           in the same order they are stored and listed. If you don't rename
           the output files, then the files will be extracted to the current
           directory with the same names they had when stored.

       ,N  Usd in create mode. Pass numeric arguments to CONFIG file. Appended
           suffix like ",2" means use 4 times more memory. Each increment
           doubles usage. You need the same memory to decompress.

       N   Used in extract mode. Extract only block N (1, 2, 3...), where 1 is
           the first block. Otherwise all blocks are extracted. The l command
           shows which files are in each block.

   Debug and Development Options
       To debug CONFIG file, use:

         zpaq [pthv]r<CONFIG>[,N...] [args...]

       the r runn the ZPAQL program in HCOMP section of configuration file F.
       The program is run once for each byte of input from the file named in
       the first argument and once at EOF with the input byte (or -1) in the A
       register. Output is to the file named in the second argument. If run
       with no arguments then take input from stdin and output to stdout.
       Modifiers are listed below.

       h   When tracing, display register and memory contents in hexadecimal
           instead of decimal.

       p   Run PCOMP (default is to run HCOMP).

       t   Trace (single step), args are numeric inputs otherwise args are
           input, output (default stdin, stdout). The arguments should be
           numbers rather than file names. The program is run once for each
           argument with the value in the A register. As each instruction is
           executed the register contents are shown. At HALT, memory contents
           are displayed.

       v   Verbose compile. Display the CONFIG file as it is being compiled.
           If an error occurs, it will be easier to locate. Modifier v is also
           useful for displaying jump targets.

       ,N  Pass numeric arguments to CONFIG file. Pass up to 9 numeric
           arguments to CONFIG file (like the c and a commands).


       -h  Display short help.


       To create an archive:

           zpaq c<CONFIG> archive.zpaq files ...

       If the archive exists then it is overwritten. File names are stored
       without a path.

       To (a)ppend to an existing archive. If the archive does not exist then
       it is created as with the c command:

           zpaq a<CONFIG> archive.zpaq files ...

       To list the contents of an archive. Files are listed in the same order
       they were added:

           zpaq l archive.zpaq

       To extract the contents of the archive. New files are created and named
       according to the stored filenames. Does not clobber existing files.
       Extracts to current directory:

           zpaq x archive.zpaq

       If the files to be extracted already exist, then zpaq will refuse to
       clobber them and skip to the next file. If the files are compressed
       with a path (folder or directory), then that directory must exist when
       the file is extracted. zpaq will not create directories.

       To extract files and renames in the order they were added to the
       archive. Clobbers any already existing output files. The number of
       files extracted is the smaller of the number of filenames on the
       command line or the number of files in the archive.

           zpaq x archive.zpaq file ...

       To extract and rename:

           zpaq x archive.zpaq files ...
           unzpaq x archive.zpaq files ...

       Files are extracted in the same order they are saved and renamed.
       Unlike using stored names, if the file exists, then it is overwritten
       (clobbered). Only files named on the command line are extracted. Any
       additional files in the archive are ignored.  For example:

           zpaq x archive.zpaq foo bar

       To extracts files like x, but without post-processing. This may be
       useful for debugging or developing config files:

           zpaq t archive.zpaq [files ...]

   Config file
       The distribution contain several default CONFIG files:

         min.cfg - for fast but poor compression.
         max.cfg - for slow but good compression.
         mid.cfg - for moderate speed and compression (default).

       Other config files are available as add-on options or you can write
       them as explained later.

       A numeric argument may be appended to CONGIF to increase memory usage
       for better compression. Each increment doubles usage. There should be
       no space before or after the comma. For example:

         zpaq cmax.cfg archive files...    = 246 MB
         zpaq cmax.cfg,1 archive files...  = 476 MB
         zpaq cmax.cfg,2 archive files...  = 938 MB
         zpaq cmax.cfg,3 archive files...  = 1861 MB
         zpaq cmax.cfg,-1 archive files... = 130 MB (negative values allowed)

       Modifiers may be in any order before the "c" or "a" command. The
       modifiers, command, and configuration file must be written together
       without any spaces. An example: to create archive with options i, p, s
       and configuration file "max.cfg". Modifiers have the following meaning:

         zpaq ipsc<CONFIG> archive.zpaq file1 file22


       Temporary directory TEMPDIR is use during optimize command o.



       Compression commands c and a need a configuration file. See examples in
       directory "/usr/share/doc/zpaq".


       See zpaq*.pdf (ZPAQ Level 1 and later) in section AVAILABILITY . It is
       anticipated that future levels (ZPAQ-2, ZPAQ-3, etc.) will be backward
       compatible, such that newer levels can read archives produced by older



       bzip2(1) gzip(1) lzop(1) lzma(1) p7zip(1) rzip(1) unace(1) unrar(1)
       unzip(1) zip(1)


       Program was written by Matt Mahoney <>

       This manual page was put together by Jari Aalto <>.
       under license GNU GPL version 2 or (at your option) any later version.
       For more information about license, visit

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