TP(5)		    UNIX Programmer's Manual		    TP(5)



NAME
     tp - DEC/mag tape formats

DESCRIPTION
     _T_p dumps files to and extracts files from DECtape and
     magtape.  The formats of these tapes are the same except
     that magtapes have larger directories.

     Block zero contains a copy of a stand-alone bootstrap pro-
     gram.  See _r_e_b_o_o_t(8).

     Blocks 1 through 24 for DECtape (1 through 62 for magtape)
     contain a directory of the tape.  There are 192 (resp. 496)
     entries in the directory; 8 entries per block; 64 bytes per
     entry.  Each entry has the following format:

	  struct {
		  char		  pathname[32];
		  unsigned short  mode;
		  char		  uid;
		  char		  gid;
		  char		  unused1;
		  char		  size[3];
		  long		  modtime;
		  unsigned short  tapeaddr;
		  char		  unused2[16];
		  unsigned short  checksum;
	  };

     The path name entry is the path name of the file when put on
     the tape.	If the pathname starts with a zero word, the
     entry is empty.  It is at most 32 bytes long and ends in a
     null byte.  Mode, uid, gid, size and time modified are the
     same as described under i-nodes (see file system _f_s(5)).
     The tape address is the tape block number of the start of
     the contents of the file.	Every file starts on a block
     boundary.	The file occupies (size+511)/512 blocks of con-
     tinuous tape.  The checksum entry has a value such that the
     sum of the 32 words of the directory entry is zero.

     Blocks above 25 (resp. 63) are available for file storage.

     A fake entry has a size of zero.

SEE ALSO
     fs(5), tp(1)

BUGS
     The _p_a_t_h_n_a_m_e, _u_i_d, _g_i_d, and _s_i_z_e fields are too small.






Printed 11/26/99	  May 15, 1985				1