NAME¶
zpaq - PAQ open standard maximum compressor
SYNOPSIS¶
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...]
DESCRIPTION¶
General¶
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 compression.
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
installation.
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 needed.
In extract mode: extract to stored paths instead of current
directory
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
modifiers.
- 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).
OPTIONS¶
- -h
- Display short help.
EXAMPLES¶
Create¶
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.
Append¶
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 ...
List¶
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
ENVIRONMENT¶
Temporary directory
TEMPDIR is use during optimize command
o.
None.
FILES¶
Compression commands
c and
a need a configuration file. See
examples in directory "/usr/share/doc/zpaq".
STANDARDS¶
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
programs.
AVAILABILITY¶
http://mattmahoney.net/dc
SEE ALSO¶
bzip2(1) gzip(1) lzop(1) lzma(1)
p7zip(1) rzip(1) unace(1) unrar(1)
unzip(1)
zip(1)
AUTHORS¶
Program was written by Matt Mahoney <matmahoney@yahoo.com>
This manual page was put together by Jari Aalto <jari.aalto@cante.net>.
under license GNU GPL version 2 or (at your option) any later version. For
more information about license, visit
<
http://www.gnu.org/copyleft/gpl.html>.