mailto(rzip64@GHSi.eu)
manpage(rzip64)(1)(December 2010)()()
manpagename(rzip64)(a large-file compression program)
manpagesynopsis()

rzip64 [OPTIONS] <files...>

manpagedescription()

rzip64 is a file compression program designed for very large files.
When processing large chunks of input data it takes advantage of repetitiv appearing 
byte patterns over long distances.

rzip64 can utilize multiple CPU cores. rzip64 can also be interrupted at any time
and be restarted later. 

manpagesection(OPTIONS SUMMARY)

Here is a summary of the options to rzip64.
verb(
 -0            fastest (worst) compression
 -6            default compression
 -9            slowest (best) compression
 -d            decompress
 -f            force overwrite of any existing files
 -G            use slices (stop-and-go mode)
 -h            print this help text
 -j            use n cores in parallel
 -k            keep existing files
 -o filename   specify the output file name
 -P            show compression progress
 -S suffix     specify compressed suffix (default \&'\&.rz\&')
 -V            show version
)

manpageoptions()

startdit()
dit(bf(-0..9)) Set the compression level from 0 to 9. The default is
to use level 6, which is a reasonable compromise between speed and
compression. The compression level is also strongly related to how much
memory rzip uses, so if you are running rzip on a machine with limited
amounts of memory then you will probably want to choose a smaller level.
dit(bf(-d)) Decompress. If this option is not used then rzip looks at
the name used to launch the program. If it contains the string
'runzip' then the -d option is automatically set.
dit(bf(-f)) If this option is not specified then rzip will not
overwrite any existing files. If you set this option then rzip will
silently overwrite any files as needed.
dit(bf(-G)) This option enables
the stop-and-go mode of rzip64. If this option is used rzip64 may be
interrupted via signal (say kill -15) at any time. Wenn rzip64 is restarted
later it will proceed compressing the file. -G always implies -9.
dit(bf(-h)) Print an options summary page
dit(bf(-j n)) Use n cpu cores in parallel. Using more than a single
core autoselects -G, too.
dit(bf(-k)) If this option is not specified then rzip will delete the
source file after successful compression or decompression. When this
option is specified then the source files are not deleted.
dit(bf(-o)) Set the output file name. If this option is not set then
the output file name is chosen based on the input name and the
suffix. The -o option cannot be used if more than one file name is
specified on the command line.
dit(bf(-P)) If this option is specified then rzip will show the
percentage progress while compressing.
dit(bf(-S)) Set the compression suffix. The default is '.rz'. 
dit(bf(-V)) Print the rzip64 version number
enddit()

manpagesection(INSTALLATION)

Just install rzip in your search path.

manpagesection(STOP-AND-GO MODE)

Compressing a large file takes time an imposes a considerable load on
the machine. It is therefore desireable to run compression tasks only at 
times where no users are working on the machine.

rzip64 can therefore be interrupted at any time by a simple kill command.
When rzip64 is restarted later it will continue the compression task until
the job is completed. One may even change the number of cores when
restarting.

manpagesection(HISTORY)

The ideas behind rzip64 were first implemented in 1998 during the work 
on rsync. That version was too slow to be practical, and was
replaced by version 2.1 in 2003.

The stop-and-go option was added in 09/2010 (version 2.2).

Multicore support was added in 12/2010. The version number was advanced to
3.0 since rzip64 with multiple treads requires a considerable amount of
memory address space that can typically be provided by 64 bit environments only.
It is not a matter of physical RAM modules but of virtual address space. Each 
cpu core requires about 900 MByte address space.

One can still compile an run rzip64 in 32 bit environments (while using only a
small number of cpu cores) but that is no longer recommended. 

manpagesection(COMPATIBILITY)

The file format for rzip64 is fully compatible to rzip 2.1 and 2.2 .

manpagesection(NOTE)

Unlike most Unix compression programs, rzip64 cannot compress or
decompress to or from standard input or standard output. That can possibly be 
changed but appears to make not much sense when -G is in use. 

manpagesection(RESSOURCES)

If you wish to report a problem or make a suggestion then please email
rzip64@GHSi.eu .

Source code and binary packages are available at rzip64.GHSi.eu .

manpageauthor()

Different people have put work in the development of rzip64.
Our thanks include
itemize(
 it() Andrew Tridgell for the first implementation of rzip
 it() The authors of bzlib for an excellent library
 it() Paul Russell for many suggestions and the debian packaging
 it() Kay Gorontzi for the stop-and-go and multicore extensions
)

rzip64 is released under the GNU General Public License version 3 or
later. Please see the file COPYING for license details.
