Unpacking the Mystery of RAR and 7-Zip Compression

For those who need to work with compressed files, particularly RAR and 7-Zip archives, understanding how they work can be crucial. In this article, we'll delve into the world of these two file compression formats and explore their features, compatibility, and usage.

The Story Behind Unrar

Gna! unrar is an open-source wrapper around unrarlib, a RAR decoding library developed by Christian Scheurer and Johannes Winkelmann. Confusingly enough, there's another open-source RAR decoder called unrar as well. However, the source code for RARLAB's unrar program is not available due to licensing restrictions.

7-Zip: A Powerful Compression Tool

7-Zip is a widely-used compression tool that supports various compression formats, including its native 7z format, which uses a modern offshoot of the LZ77 algorithm. The 7-Zip app is open-source and available under the LGPL license. For Linux users, there's also a command-line client package called p7zip that provides two executables: 7z and 7za.

RAR: A Proprietary Format

RAR - short for Roshal Archive - is a proprietary file compression format developed by Eugene Roshal. While it's not open-source, RARLAB offers uncompress-only clients for various operating systems at no charge. However, the source code for RAR decoder is forbidden from being used to develop any form of RAR encoder.

Unpacking and Uncompressing with 7-Zip

To extract files from an archive using 7-Zip, you can use the `e` function to extract all files to the current working directory or the `x` function to preserve file paths. The basic syntax is `7z function options filename.7z`. For example, to uncompress an archive, use `7z x myfile.7z`.

While RAR and 7-Zip compression formats originated on Windows, they can be handled with the right software on Linux as well. By understanding their features and usage, you'll be better equipped to work with these compressed files without any trouble.

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