cpio(4)

NAME
     cpio - format of cpio archive

DESCRIPTION
     The header structure, when the -c option of cpio(1) is not used, is:

          struct {
                     short    h_magic,
                              h_dev;
                     ushort   h_ino,
                              h_mode,
                              h_uid,
                              h_gid;
                     short    h_nlink,
                              h_rdev,
                              h_mtime[2],
                              h_namesize,
                              h_filesize[2];
                     char     h_name[h_namesize rounded to word];
          } Hdr;

     When the -c option is used, the header information is described by:

       sscanf(Chdr,"%6lo%6lo%6llo%6lo%6lo%6lo%6lo%6lo%11lo%6o%11llo%s",
         &Hdr.h_magic, &Hdr.h_dev, &Hdr.h_ino, &Hdr.h_mode,
         &Hdr.h_uid, &Hdr.h_gid, &Hdr.h_nlink, &Hdr.h_rdev,
         &Hdr.g_mtime, &Hdr.h_namesize,&Hdr.h_filesize,Hdr.h_name);
    Other archive formats (e.g ustar) use other sscanf strings.
    The contents of each file are recorded in an element of the array of
    varying length structures, archive, together with other items describing
    the file.  Every instance of h_magic contains the constant 070707 (octal).
    The items h_dev through h_mtime have meanings explained in stat(2).  The
    length of the null-terminated path name h_name, including the null byte,
    is given by h_namesize.

     The last record of the archive always contains the name TRAILER!!!.
     Special files, directories, and the trailer are recorded with h_filesize
     equal to zero.

SEE ALSO
     cpio(1), find(1), stat(2)