TAR(F)                   XENIX System V                    TAR(F)



     Name
          tar - archive format

     Description
          The command tar(C) dumps files to and extracts files from
          backup media or the hard disk.

          Each file is archived in contiguous blocks, the first block
          being occupied by a header, whose format is given below, and
          the subsequent blocks of the files occupying the following
          blocks.  All headers and file data start on 512 byte block
          boundaries and any spare unused space is padded with
          garbage. The format of a header block is as follows:

               #define TBLOCK 512
               #define NBLOCK 20
               #define NAMSIZ 100
               union hblock {
                    char dummy[TBLOCK];
                    struct header {
                         char name[NAMSIZ];
                         char mode[8];
                         char uid[8];
                         char gid[8];
                         char size[12];
                         char mtime[12];
                         char chksum[8];
                         char linkflag;
                         char linkname[NAMSIZ];
                         char extno[4];
                         char extotal[4];
                         char efsize[12];
                    } dbuf;
               } dblock;

          The name entry is the path name of the file when archived.
          If the pathname starts with a zero word, the entry is empty.
          It is at most 100 bytes long and ends in a null byte. Mode,
          uid, gid, size, and time modified are the same as described
          under i-nodes (refer to filesystem(F)).  The checksum entry
          has a value such that the sum of the words of the directory
          entry is zero.

          If the entry corresponds to a link, then linkname contains
          the pathname of the file to which this entry is linked and
          linkflag gives a count of the links.  No data is put in the
          archive file.

     See Also
          filesystem(F), tar(C)





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