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tar program is invoked as either one of:
tar option… [name]… tar letter… [argument]… [option]… [name]…
The second form is for when old options are being used.
You can use
tar to store files in an archive, to extract them from
an archive, and to do other types of archive manipulation. The primary
tar, which is called the operation, specifies
which action to take. The other arguments to
tar are either
options, which change the way
tar performs an operation,
or file names or archive members, which specify the files or members
tar is to act on.
You can actually type in arguments in any order, even if in this manual
the options always precede the other arguments, to make examples easier
to understand. Further, the option stating the main operation mode
tar main command) is usually given first.
Each name in the synopsis above is interpreted as an archive member
name when the main command is one of `--compare'
(`--diff', `-d'), `--delete', `--extract'
(`--get', `-x'), `--list' (`-t') or
`--update' (`-u'). When naming archive members, you
must give the exact name of the member in the archive, as it is
printed by `--list'. For `--append' (`-r') and
`--create' (`-c'), these name arguments specify
the names of either files or directory hierarchies to place in the archive.
These files or hierarchies should already exist in the file system,
prior to the execution of the
tar interprets relative file names as being relative to the
tar will make all file names relative
(by removing leading slashes when archiving or restoring files),
unless you specify otherwise (using the `--absolute-names'
option). See section Absolute File Names, for more information about
If you give the name of a directory as either a file name or a member
tar acts recursively on all the files and directories
beneath that directory. For example, the name `/' identifies all
the files in the file system to
The distinction between file names and archive member names is especially
important when shell globbing is used, and sometimes a source of confusion
for newcomers. See section Wildcards Patterns and Matching, for more information about globbing.
The problem is that shells may only glob using existing files in the
file system. Only
tar itself may glob on archive members, so when
needed, you must ensure that wildcard characters reach
being interpreted by the shell first. Using a backslash before `*'
or `?', or putting the whole argument between quotes, is usually
sufficient for this.
Even if names are often specified on the command line, they can also be read from a text file in the file system, using the `--files-from=file-of-names' (`-T file-of-names') option.
If you don't use any file name arguments, `--append' (`-r'),
`--delete' and `--concatenate' (`--catenate',
`-A') will do nothing, while `--create' (`-c')
will usually yield a diagnostic and inhibit
The other operations of
`--extract', `--compare', and `--update')
will act on the entire contents of the archive.
Besides successful exits, GNU
tar may fail for
many reasons. Some reasons correspond to bad usage, that is, when the
tar command line is improperly written. Errors may be
encountered later, while processing the archive or the files. Some
errors are recoverable, in which case the failure is delayed until
tar has completed all its work. Some errors are such that
it would be not meaningful, or at least risky, to continue processing:
tar then aborts processing immediately. All abnormal exits,
whether immediate or delayed, should always be clearly diagnosed on
stderr, after a line stating the nature of the error.
Possible exit codes of GNU
tar are summarized in the following
`Some files differ'. If tar was invoked with `--compare' (`--diff', `-d') command line option, this means that some files in the archive differ from their disk counterparts (see section Comparing Archive Members with the File System). If tar was given `--create', `--append' or `--update' option, this exit code means that some files were changed while being archived and so the resulting archive does not contain the exact copy of the file set.
`Fatal error'. This means that some fatal, unrecoverable error occurred.
tar has invoked a subprocess and that subprocess exited with a
nonzero exit code,
tar exits with that code as well.
This can happen, for example, if
tar was given some
compression option (see section Creating and Reading Compressed Archives) and the external compressor program
failed. Another example is
rmt failure during backup to the
remote device (see section Remote Tape Server).
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