


     TTTTAAAARRRRXXXX((((1111))))		 XXXXEEEENNNNIIIIXXXX 3333....0000 ((((22226666 JJJJuuuullllyyyy 1111999999990000))))	       TTTTAAAARRRRXXXX((((1111))))



     NNNNAAAAMMMMEEEE
	  tarx - recover files from damaged tar-format archives

     SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
	  ttttaaaarrrrxxxx [ ----tttt ] [	----bbbb blockfactor ] [ ----eeee errlimit ] [ ----EEEE eoflimit
	  ] name ...

     DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
	  _T_a_r_x is used to list and recover files from a	damaged	_t_a_r(1)
	  archive.  It uses a simplistic pattern-matching approach to
	  identify _t_a_r header blocks.  It will cheerfully persist
	  despite all sorts of bad things about	the archive (such as
	  wrong	checksums, read	errors,	and scraped-off	magnetic
	  surface...), up to a maximum of _e_r_r_l_i_m_i_t (default 3) hard
	  errors in a row or _e_o_f_l_i_m_i_t (default 2) EOFs in a row.  Such
	  events are reported but don't	terminate operations.  The _t_a_r
	  archive is read from standard	input.

	  With the ----tttt option, _t_a_r_x lists the file names	it sees	in the
	  archive.

	  Without the ----tttt option, _t_a_r_x takes file or directory _n_a_m_es as
	  arguments and	attempts to extract them from the archive.
	  (If no _n_a_m_es are given, _t_a_r_x extracts	everything it can
	  find.) _T_a_r_x is not willing to	create directories, however,
	  so these must	be made	manually beforehand if they do not
	  already exist.  Files	are owned by the user, and have	his
	  default permissions.

	  _T_a_r_x allocates a read	buffer of _b_l_o_c_k_f_a_c_t_o_r*512 bytes, where
	  the default _b_l_o_c_k_f_a_c_t_o_r is 400 (to allow for the very	large
	  blocks sometimes found on cartridge tapes), and attempts a
	  full-sized read each time.  It copes properly	with getting
	  less than it expected, although it does insist that the
	  result be a multiple of 512 bytes.  When dealing with	cranky
	  tape drives or other special situations, or severely short
	  of memory, or	working	on a 16-bit machine, it	may be useful
	  to specify a smaller _b_l_o_c_k_f_a_c_t_o_r.  (Notably, on 16-bit
	  machines 126 is often	the maximum that will work.)
	  Specifying a larger _b_l_o_c_k_f_a_c_t_o_r may be necessary if tape
	  blocks are truly enormous.

     EEEEXXXXAAAAMMMMPPPPLLLLEEEE
	  ``tarx -t </dev/rmt0 >filelist'' lists all files on the tape
	  mounted on /dev/rmt0 and places the results in ``filelist''.

	  ``tarx joe/precious </dev/rmt0'' restores the	file
	  ``joe/precious'' from	the tape mounted on /dev/rmt0.	The
	  directory ``joe'' must already exist.

     SSSSEEEEEEEE AAAALLLLSSSSOOOO
	  tar(1)



     Page 1					     (printed 8/16/94)






     TTTTAAAARRRRXXXX((((1111))))		 XXXXEEEENNNNIIIIXXXX 3333....0000 ((((22226666 JJJJuuuullllyyyy 1111999999990000))))	       TTTTAAAARRRRXXXX((((1111))))



     HHHHIIIISSSSTTTTOOOORRRRYYYY
	  Written by Henry Spencer, Univ. of Toronto Zoology, based on
	  older	programs by the	same author.  This software is public
	  domain.  Original manual page	by Chris Robertson.

     BBBBUUUUGGGGSSSS
	  _T_a_r_x should be smarter about directories and permissions.

	  Arguably should use the _t_a_r header-block checksum, instead
	  of the slightly-arcane pattern matcher, to identify header
	  blocks.

	  A _t_a_r	archive	containing a file which	is itself a _t_a_r
	  archive will cause considerable confusion.









































     Page 2					     (printed 8/16/94)



