Detailed linux file compression format
Principle compressed files
In computer science and information theory, the data is compressed or encoded source bits (or other information related to the unit) represented by the less information than the non-coded data according to a particular coding scheme process. For example, if we will "compression" is encoded as "comp" then this article can be represented with fewer bits. A common example is a ZIP file format, which not only provides compression but also as archiving tools (Archiver), able to store many files into a single file.
Simply put, that is, after compression software compressed file called a compressed file, the file compression is the binary code compression, to reduce adjacent 0,1 code, such as there is 000000, you can put it into writing 6 0 60, to reduce the space the file.
The basic principle of the compressed file is repeated bytes in the file to find and establish a same byte "dictionary" file, and is represented by a code, such as there are several in the same document there is a word "People's Republic of China" with a and writes the code represents the "dictionary" file, so that you can achieve the purpose of narrowing the file.
Common compression formats
- zip
ZIP file format is a data compression and file storage file format, formerly known Deflate, as the inventor Phil Katz (Phil Katz), he published the data in this format in January 1989. ZIP typically use the suffix ".zip", its MIME format application / zip. Current, ZIP compression format is one of several mainstream formats, including its competitors 7z format RAR formats and open source. From the comparison of the performance, RAR and 7z format higher than the ZIP format compression ratio, while 7-Zip compression due to the provision of free tools and gradually applied in more fields. Microsoft from Windows ME operating system begins to built-in support for zip format, even if not installed decompression software on the user's computer, can be opened and compressed files produced zip format, OS X and popular Linux operating system on the zip format provides similar support. So if the spread and distribution of documents on the network, zip format is often the most common choice.
- gzip
Gzip is referred to several file compression program, usually referring to realize the GNU project, gzip herein represent GNU zip. This is also often used to represent gzip file format. The software's author is Jean-loup Gailly and Mark Adler. The first public release in October 31, 1992, version 0.1, February 1993, released version 1.0
- bzip2
bzip2 is Julian Seward development and in accordance with data compression free software / open source software protocol published algorithms and procedures. Seward in July 1996 the first public release of bzip2 0.15 version, in subsequent years this compression tool stability is improved and increasingly popular, Seward released version 1.0 in late 2000.
- 7z
In computer science, 7z can use a variety of compression algorithms for data compression file format. This format originally implemented and using 7-Zip, but this file format is public, and 7-Zip open source software itself is also under GNU Lesser General Public License (GNU the LGPL) protocol. LZMA latest version of the current software development kit is v15.12.
- rar
RAR is a proprietary file format for data compression and archiving package, the developer is Eugene Rochelle (Russian: Евгений Лазаревич Рошал, Latin transliteration: Yevgeny Lazarevich Roshal), RAR full name is "Roshal ARchive" , that is, "Rochelle archive" means. First public version RAR 1.3 released in 1993.
Eugene Rochelle, March 10, 1972 was born in Russia. Graduated from the University of Chelyabinsk in Russia (Chelyabinsk Technical University, State University today Nanwu La) author, is FAR file manager. He developed a program compression or decompression RAR files, originally for DOS, and later ported to other platforms. The main version of Windows encoder, called WinRAR, distributed as shareware. But Rochelle disclosed decoder source code, UnRAR decoder license to compile allowed to publish RAR-compatible encoder under conditions that allow conditional release and modified freely, and RAR encoder has been patented.
Recent developer is Eugene's brother Alexander Rochelle Rochelle. Although Patent decoder, compiled decompressor remains in the number of platforms, such as open source 7-Zip.
Common compressed file compression and decompression
| File extension | Explanation | compression | unzip |
|---|---|---|---|
| *.zip | packaged compressed zip file | zip fileName.zip dirName | unzip fileName.zip |
| *.rar | rar file compression program | rar a fileName.rar dirName | rar x fileName.rar |
| * .7z | 7zip file compression program | 7z a fileName.7z dirName | 7z x fileName.7z |
| * tar | tar packaged, uncompressed file | tar cvf fileName.tar dirName | tar xvf fileName.tar |
| *.gz | the gzip (GNU zip) compressed files | gzip fileName | gzip -d fileName.gz |
| * .Bz2 | packaged tar, gzip file compression program | bzip2 -z FileName | bzip2 -d FileName.bz2 |
| * .Tar.gz | packaged tar, gzip file compression program | tar zcvf FileName.tar.gz dirName | tar zxvf FileName.tar.gz |
| * .tar.xz | tar package, xz compressed program files | tar cvJf fileName.tar.xz dirName | tar -xvJf fileName.tar.xz |
| * .tar.bz2 | tar package, bzip2 compressed program files | tar jcvf FileName.tar.bz2 dirName | tar jxvf FileName.tar.bz2 |
| *.WITH | decompress rar files compress command | compress fileName | uncompress fileName.Z |