Archiving Data

A file-archiving tool collects a group of files into a single package file that you can easily move around.

`tar`

tar is a program used to archive various data files into a single file, called an archive file.

stands for tape archiver
original files remain on disk
archive file is compressed on the fly into a tarball
- often used for transferring multiple files between computers in one step
-c used to create a new archive
-x to extract the archive
-t list contents of an archive file to stdout

gzip, bzip2, and xz programs on Linux are used to compress individual files.

generally, gzip provides the least compression, xz the most
tar supports all three compression standards
- uses unique filename extensions for each standard:
  - .tgz for tarballs compressed with gzip
  - .tbz or .tbz2 for tarballs compressed with bzip2
  - .txz for tarballs compressed with xz

Compression program	Uncompression program	Filename extension	`tar` Option
`gzip`	`gunzip`	`.gz`	`-z`
`bzip2`	`bunzip2`	`.bz2`	`-j`
`xz`	`unxz`	`.xz`	`-J`

these all apply lossless compression
- data recovered by uncompressing the file is identical to the original
some graphics, audio, and audiovisual files apply lossy compression
- some data is discarded
- these tools should never be used on program files, system configuration files, or most user data files
tar supports only lossless compression

zip is an archive and compression tool similar to tarballs, commonly used outside of Unix and Linux.