RAR (file format)

RAR File Format Overview
– RAR is a proprietary archive file format developed by Eugene Roshal in 1993.
– It supports data compression, error correction, and file spanning.
– RAR compression applications and libraries are proprietary software.
– RAR supports all versions of the RAR archive format, including RAR3 and RAR5.
– The RAR compression algorithm is proprietary and cannot be reverse engineered without written permission.
– RAR files can be created and extracted using software like WinRAR, 7-Zip, and libarchive.

RAR Versions and Software Support
– RAR file format revision history includes versions 1.3, 1.5, 2.0, 2.9, 5.0, and 5.0+.
– Each version introduced various changes and improvements.
– Version 2.9 introduced encryption, file data compression algorithm improvements, and support for larger archives.
– Version 5.0 increased compression dictionary size, maximum path length, and introduced faster compression and decompression.
– Version 5.0+ is partially supported by WinRAR 5.0 and later, and fully supported by WinRAR 7.0 and later.
– WinRAR is the software for Microsoft Windows that supports RAR files.
– RAR software is also available for Linux, FreeBSD, macOS, and Android.
– Archive extraction is supported natively in ChromeOS.
– WinRAR supports the Windows GUI, while other versions run as console commands.
– Different versions of WinRAR have compatibility limitations with older operating systems.

Creating and Extracting RAR Files
– RAR files can be created legally only with commercial software like WinRAR and RAR for Android.
– Command-line RAR and other software with permission from Alexander Roshal can also create RAR files.
– Reverse engineering is forbidden by the software license agreements.
– RARLAB distributes the unrar program, which can unpack RAR files.
– 7-Zip, a free and open-source program, can unpack RAR5 archives.
– PeaZip is a free RAR unarchiver that supports both pre-RAR5 and RAR5 formats.
– The Unarchiver is a proprietary software unarchiver for RAR and other formats, available on macOS.

Other Uses of RAR
– The file extension ‘.rar’ is also used for the unrelated Resource Adapter aRchive file format.
– The Resource Adapter Archive (RAR) is a packaging format used in Java Enterprise Edition (Java EE) for deploying resource adapters.
– RAR is also used as an abbreviation for Resource Adapter Archive in the context of Java EE.

Related Archive Formats and Tools
– The filename extension ‘.cbr’ is commonly used for comic book archive files, which are essentially RAR archives containing images.
– There are many other archive formats available, such as tar, 7-zip, gz, and more.
– Comparison of archive formats and file archivers can help in choosing the right tool for specific needs.
– Data corruption, bit rot, and disc rot are potential risks that can affect archived files.
– The XADMaster library, licensed under the GNU Lesser General Public License, also supports RAR extraction.