NAME

cpio − format of cpio archive

DESCRIPTION

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

struct {
    shortc_magic,
        c_dev;
    ushortc_ino,
        c_mode,
        c_uid,
        c_gid;
    shortc_nlink,
        c_rdev,
        c_mtime[2],
        c_namesize,
        c_filesize[2];
    charc_name[c_namesize rounded to word];
} Hdr;

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

sscanf(Chdr,"%6ho%6ho%6ho%6ho%6ho%6ho%6ho%6ho%11lo%6ho%11lo",
          &Hdr.c_magic,&Hdr.c_dev,&Hdr.c_ino,&Hdr.c_mode,
          &Hdr.c_uid,&Hdr.c_gid,&Hdr.c_nlink,&Hdr.c_rdev,
          &Longtime,&Hdr.c_namesize,&Longfile);

Longtime and Longfile are equivalent to Hdr.c_mtime and Hdr.c_filesize, respectively.  The contents of each file are recorded together with other items describing the file.  Every instance of c_magic contains the constant 070707 (octal).  The items c_dev through c_mtime have meanings explained in stat(2). The length of the null-terminated path name c_name, including the null byte, is given by c_namesize. 

The last record of the archive always contains the name TRAILER!!!.  Directories and the trailer are recorded with c_filesize equal to zero. 

It will not always be the case that c_dev and c_ino correspond to the results of stat(), but the values are always sufficient to tell whether two files in the archive are linked to each other. 

When a device special file is archived by HP-UX cpio (using the -x option), c_rdev contains a magic constant which is dependent upon the implementation doing the writing.  H_rdev flags the device file as an HP-UX 32-bit device specifier, and c_filesize contains the 32-bit device specifier (see stat(2)). If the -x option is not present, special files are not archived or restored.  Non- device special files are never restored.

SEE ALSO

cpio(1), find(1), stat(2). 

STANDARDS CONFORMANCE

cpio: XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1

Hewlett-Packard Company  —  HP-UX Release 9.0: August 1992