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

NAME
     tp - DEC/mag tape formats

DESCRIPTION
     The command _t_p dumps files to and extracts files from DEC-
     tape 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.

     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];
               int  mode;
               char uid;
               char gid;
               char unused1;
               char size[3];
               long modtime;
               int  tapeaddr;
               char unused2[16];
               int  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_i_l_s_y_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
     tp(1), filsys(5)

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 5/17/83                                                 1