4.3BSD-UWisc/man/cat5/tp.5

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 12/27/86          May 15, 1985                          1