


TAR(1)		    UNIX Programmer's Manual		   TAR(1)



NAME
     tar - tape archiver

SYNOPSIS
     tar [ key ] [ name ... ]

DESCRIPTION
     _T_a_r saves and restores multiple files on a single file (usu-
     ally a magnetic tape, but it can be any file). _T_a_r's actions
     are controlled by the _k_e_y argument.  The _k_e_y is a string of
     characters containing at most one function letter and possi-
     bly one or more function modifiers.  Other arguments to _t_a_r
     are file or directory names specifying which files to dump
     or restore.  In all cases, appearance of a directory name
     refers to the files and (recursively) subdirectories of that
     directory.

     The function portion of the key is specified by one of the
     following letters:

     r	     The named files are written on the end of the tape.
	     The c function implies this.

     x	     The named files are extracted from the tape.  If the
	     named file matches a directory whose contents had
	     been written onto the tape, this directory is
	     (recursively) extracted.  The owner, modification
	     time, and mode are restored (if possible).  If no
	     file argument is given, the entire content of the
	     tape is extracted.  Note that if multiple entries
	     specifying the same file are on the tape, the last
	     one overwrites all earlier.

     t	     The names of the specified files are listed each
	     time they occur on the tape.  If no file argument is
	     given, all of the names on the tape are listed.

     u	     The named files are added to the tape if either they
	     are not already there or have been modified since
	     last put on the tape.

     c	     Create a new tape; writing begins on the beginning
	     of the tape instead of after the last file.  This
	     command implies r.

     The following characters may be used in addition to the
     letter which selects the function desired.

     o	       On output, tar normally places information speci-
	       fying owner and modes of directories in the
	       archive.  Former versions of tar, when encounter-
	       ing this information will give error message of



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TAR(1)		    UNIX Programmer's Manual		   TAR(1)



	       the form
		    "<name>/: cannot create".
	       This modifier will suppress the directory informa-
	       tion.

     p	       This modifier says to restore files to their ori-
	       ginal modes, ignoring the present _u_m_a_s_k(2).
	       Setuid and sticky information will also be
	       restored to the super-user.

     0, ..., 9 This modifier selects an alternate drive on which
	       the tape is mounted.  The default is drive 0 at
	       1600 bpi, which is normally /dev/rmt8.

     v	       Normally _t_a_r does its work silently.  The v (ver-
	       bose) option makes _t_a_r print the name of each file
	       it treats preceded by the function letter.  With
	       the t function, the verbose option gives more
	       information about the tape entries than just their
	       names.

     w	       _T_a_r prints the action to be taken followed by file
	       name, then wait for user confirmation. If a word
	       beginning with `y' is given, the action is done.
	       Any other input means don't do it.

     f	       _T_a_r uses the next argument as the name of the
	       archive instead of /dev/rmt?. If the name of the
	       file is `-', tar writes to standard output or
	       reads from standard input, whichever is appropri-
	       ate. Thus, _t_a_r can be used as the head or tail of
	       a filter chain.	_T_a_r can also be used to move
	       hierarchies with the command
		 cd fromdir; tar cf - . | (cd todir; tar xf -)

     b	       _T_a_r uses the next argument as the blocking factor
	       for tape records. The default is 20 (the maximum).
	       This option should only be used with raw magnetic
	       tape archives (See f above).  The block size is
	       determined automatically when reading tapes (key
	       letters `x' and `t').

     l	       tells _t_a_r to complain if it cannot resolve all of
	       the links to the files dumped.  If this is not
	       specified, no error messages are printed.

     m	       tells _t_a_r not to restore the modification times.
	       The modification time will be the time of extrac-
	       tion.

     h	       Force _t_a_r to follow symbolic links as if they were
	       normal files or directories.  Normally, _t_a_r does



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TAR(1)		    UNIX Programmer's Manual		   TAR(1)



	       not follow symbolic links.

     B	       Forces input and output blocking to 20 blocks per
	       record.	This option was added so that _t_a_r can
	       work across a communications channel where the
	       blocking may not be maintained.

     C	       If a file name is preceded by -C, then _t_a_r will
	       perform a _c_h_d_i_r(2) to that file name.  This allows
	       multiple directories not related by a close common
	       parent to be archived using short relative path
	       names.  For example, to archive files from
	       /usr/include and from /etc, one might use
		    tar c -C /usr include -C / etc

     Previous restrictions dealing with _t_a_r's inability to prop-
     erly handle blocked archives have been lifted.

FILES
     /dev/rmt?
     /tmp/tar*

SEE ALSO
     tar(5)

DIAGNOSTICS
     Complaints about bad key characters and tape read/write
     errors.
     Complaints if enough memory is not available to hold the
     link tables.

BUGS
     There is no way to ask for the _n-th occurrence of a file.
     Tape errors are handled ungracefully.
     The u option can be slow.
     The current limit on file name length is 100 characters.
     There is no way selectively to follow symbolic links.
     When extracting tapes created with the r or u options,
     directory modification times may not be set correctly.
















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