Free gzip software for linux

gzip (GNU zip) is a very popular data compression program.

gzip (GNU zip) is a compression utility designed to be a replacement for compress. Its main advantages over compress are much better compression and freedom from patented algorithms. The GNU Project uses it as the standard compression program for its system.

gzip currently uses by default the LZ77 algorithm used in zip 1.9 (the portable pkzip compatible archiver). The gzip format was however designed to accommodate several compression algorithms. See below for a comparison of zip and gzip.

gunzip can currently decompress files created by gzip, compress or pack. The detection of the input format is automatic. For the gzip format, gunzip checks a 32 bit CRC. For pack, gunzip checks the uncompressed length. The compress format was not designed to allow consistency checks. However gunzip is sometimes able to detect a bad .Z file because there is some redundancy in the .Z compression format.
If you get an error when uncompressing a .Z file, do not assume that the .Z file is correct simply because the standard uncompress does not complain. This generally means that the standard uncompress does not check its input, and happily generates garbage output.

gzip produces files with a .gz extension. Previous versions of gzip used the .z extension, which was already used by the pack Huffman encoder. gunzip is able to decompress .z files (packed or gziped).

Several planned features are not yet supported (see the file TODO). See the file NEWS for a summary of changes since 0.5. See the file INSTALL for installation instructions. Some answers to frequently asked questions are given in the file INSTALL, please read it. (In particular, please dont ask me once more for an /etc/magic entry.)

WARNING: on several systems, compiler bugs cause gzip to fail, in particular when optimization options are on. See the section "Special targets" at the end of the INSTALL file for a list of known problems. For all machines, use "make check" to check that gzip was compiled correctly. Try compiling gzip without any optimization if you have a problem.

Usage: gzip [-cdfhlLnNrtvV19] [-S suffix] [file ...]
-c --stdout write on standard output, keep original files unchanged
-d --decompress decompress
-f --force force overwrite of output file and compress links
-h --help give this help
-l --list list compressed file contents
-L --license display software license
-n --no-name do not save or restore the original name and time stamp
-N --name save or restore the original name and time stamp
-q --quiet suppress all warnings
-r --recursive operate recursively on directories
-S .suf --suffix .suf use suffix .suf on compressed files
-t --test test compressed file integrity
-v --verbose verbose mode
-V --version display version number
-1 --fast compress faster
-9 --best compress better
--rsyncable Make rsync-friendly archive
file... files to (de)compress. If none given, use standard input.

mod_gzip is an external extension module for the WWWs most popular web server arrowApache, created in autumn, 2000.

Its implementation allows for using the compression method arrowgzip for a significant reduction of the volume of web page content served over the arrowHTTP protocol.

Currently mod_gzip uses the gzip compression level 6. This is hard-coded by the assignment gz1->level = 6 inside the function gz1_init.

The higher the compression level (gzip allows values between 1 and 9), the better the compression effect, but the higher the CPU time consumption as well. By adapting this compression level a user could solve the trade-off between CPU load and bandwidth saving according to his own requirements.

Own experiments have shown that level 3 already takes you near the effect of compression level 6 - at least the choice between these two values should be left to the user.

Thus it would be reasonable to have this compression level configurable by offering another directive mod_gzip_compression_level.

Apache::Dynagzip is a mod_perl extension for Apache-1.3.X to compress the response with gzip format.

This Apache handler provides dynamic content compression of the response data stream for HTTP/1.0 and HTTP/1.1 requests. Standard gzip compression is optionally combined with an extra light compression that eliminates leading blank spaces and/or blank lines within the source document. An extra light compression could be applied even when the client (browser) is not capable to decompress gzip format.

Handler helps to compress the outbound HTML content usually by 3 to 20 times, and provides a list of useful features. This is particularly useful for compressing outgoing web content that is dynamically generated on the fly (using templates, DB data, XML, etc.), when at the time of the request it is impossible to determine the length of the document to be transmitted. Support for Perl, Java, and C source generators is provided.

Besides the benefits of reduced document size, this approach gains efficiency from being able to overlap the various phases of data generation, compression, transmission, and decompression. In fact, the browser can start to decompress a document, which has not yet been completely generated.

rzip is a compression program, similar in functionality to bzip2 or gzip, but able to take advantage long distance redundencies in files, which can sometimes allow rzip to produce much better compression ratios than other programs.
The original idea behind rzip is described in my PhD thesis (see http://samba.org/~tridge/), but the implementation in this version is considerably improved from the original implementation.
The new version is much faster and also produces a better compression ratio.
Advantages
The principal advantage of rzip is that it has an effective history buffer of 900 Mbyte. This means it can find matching pieces of the input file over huge distances compared to other commonly used compression programs. The gzip program by comparison uses a history buffer of 32 kbyte and bzip2 uses a history buffer of 900 kbyte.
The second advantage of rzip over bzip2 is that it is usually faster. This may seem surprising at first given that rzip uses the bzip2 library as a backend (for handling the short-range compression), but it makes sense when you realise that rzip has usually reduced the data a fair bit before handing it to bzip2, so bzip2 has to do less work.
Disadvantages
rzip is not for everyone! The two biggest disadvantages are that you cant pipeline rzip (so it cant read from standard input or write to standard output), and that it uses lots of memory. A typical compression run on a large file might use a couple of hundred MB of ram. If you have ram to burn and want the best possible compression rate then rzip is probably for you, otherwise stick with bzip2 or gzip.
Enhancements:
- Added -L compression level option
- minor portability fixes
- fixed a bug that could cause some files to not be able to be uncompressed

ziproxy is forwarding, non-caching, compressing proxy server. ziproxy squeezes images by converting them to low quality jpegs and optionally can also gzip HTML and other text-like data. ziproxy is intended to free bandwidth on dialup connections.

Can be run using inetd, xinetd, or you can use simple replacement "netd" that is part of this package. Former name of this project was mwp_proxy.

Installation:

To see your options, run:

./configure --help

Then run:

./configure

make

make install

Zlibc is a read-only compressed file-system emulation. It allows executables to uncompress their data files on the fly. No kernel patch, no re-compilation of the executables and the libraries is needed.

Using gzip -9, a compression ratio of 1:3 can easily be achieved! (See examples below). This program has (almost) the same effect as a (read-only) compressed file system.

This package overrides the "open" function (and other similar system call functions) of the C library. this package uses the LD_PRELOAD variable to redirect the dynamic linker to use the relevant functions of uncompress.o instead of the shared library.

JZlib is a re-implementation of zlib in pure Java. The first and final aim for hacking this was to add packet compression support to pure Java SSH systems.
Main features:
- Needless to say, JZlib can inflate data, which is deflated by zlib and JZlib can generate deflated data, which is acceptable and is inflated by zlib.
- JZlib supports all compression level and all flushing mode in zlib.
- JZlib does not support gzip file handling supports.
- The performance has not been estimated yet, but it will not be so bad in deflating/inflating data stream on the low bandwidth network.
- JZlib is licensed under BSD style license
- Any invention has not been done in developing JZlib. So, if zlib is patent free, JZlib is also not covered by any patents.
Enhancements:
- change: memory and performance optimizations in the inflate operation.
- Many thanks to Paul Wakefield at platx.org(http://www.platx.org), who suggested above improvements.
- change: added the nowrap argument to Z{Input,Output}?Stream.

libfirerpc is a library that provides an easy interface for C programs to make remote function queries via the XML RPC protocol.

It supports SSL/TLS, HTTP authentication, HTTP 1.1 persistent connections and pipelining. It also supports POST data compression via bzip2 and response compression via bzip2, gzip, deflate and compress.