tar: What tar Does

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1 1.3 What 'tar' Does
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1 The 'tar' program provides the ability to create 'tar' archives, as well
1 as various other kinds of manipulation.  For example, you can use 'tar'
1 on previously created archives to extract files, to store additional
1 files, or to update or list files which were already stored.
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1    Initially, 'tar' archives were used to store files conveniently on
1 magnetic tape.  The name 'tar' comes from this use; it stands for 't'ape
1 'ar'chiver.  Despite the utility's name, 'tar' can direct its output to
1 available devices, files, or other programs (using pipes).  'tar' may
1 even access remote devices or files (as archives).
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1    You can use 'tar' archives in many ways.  We want to stress a few of
1 them: storage, backup, and transportation.
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1 Storage
1      Often, 'tar' archives are used to store related files for
1      convenient file transfer over a network.  For example, the GNU
1      Project distributes its software bundled into 'tar' archives, so
1      that all the files relating to a particular program (or set of
1      related programs) can be transferred as a single unit.
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1      A magnetic tape can store several files in sequence.  However, the
1      tape has no names for these files; it only knows their relative
1      position on the tape.  One way to store several files on one tape
1      and retain their names is by creating a 'tar' archive.  Even when
1      the basic transfer mechanism can keep track of names, as FTP can,
1      the nuisance of handling multiple files, directories, and multiple
1      links makes 'tar' archives useful.
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1      Archive files are also used for long-term storage.  You can think
1      of this as transportation from the present into the future.  (It is
1      a science-fiction idiom that you can move through time as well as
1      in space; the idea here is that 'tar' can be used to move archives
1      in all dimensions, even time!)
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1 Backup
1      Because the archive created by 'tar' is capable of preserving file
1      information and directory structure, 'tar' is commonly used for
1      performing full and incremental backups of disks.  A backup puts a
1      collection of files (possibly pertaining to many users and
1      projects) together on a disk or a tape.  This guards against
1      accidental destruction of the information in those files.  GNU
1      'tar' has special features that allow it to be used to make
1      incremental and full dumps of all the files in a file system.
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1 Transportation
1      You can create an archive on one system, transfer it to another
1      system, and extract the contents there.  This allows you to
1      transport a group of files from one system to another.
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