7-Zip
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| Developer(s) | Igor Pavlov | ||||
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| Initial release | 1999 | ||||
| Development status | Active | ||||
| Operating system | Microsoft Windows, Linux, OSX | ||||
| License | GNU GPL/LGPL | ||||
| Website | [1] | ||||
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7-Zip is a free and open-source file archiver, a utility used to place groups of files within compressed containers known as "archives". It is developed by Igor Pavlov and was first released in 1999. 7-Zip has its own archive format called 7z introduced in 2001, but can read and write several others.
Installation
Download and run the installer for your operating system from the [2].
Archive formats
By default, 7-Zip creates 7z-format archives with a .7z file extension. Each archive can contain multiple directories and files. As a container format, security or size reduction are achieved by looking for similarities throughout the data using a stacked combination of filters. These can consist of pre-processors, compression algorithms, and encryption filters.
The core 7z compression uses a variety of algorithms, the most common of which are bzip2, PPMd, LZMA2, and LZMA. Developed by Pavlov, LZMA is a relatively new system, making its debut as part of the 7z format. LZMA uses an LZ-based sliding dictionary of up to 3840 MB in size, backed by a range coder.
The native 7z file format is open and modular. File names are stored as Unicode.
The 7z file format specification is distributed with the program's source code, in the "doc" sub-directory.