cpio(5) — AIX PS/2 1.2.1



CPIO(5,F)                   AIX Technical Reference                   CPIO(5,F)



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cpio



PURPOSE

Describes copy in and out (cpio) archive file.

DESCRIPTION

When the -c flag of the cpio command is not used, the header structure is:

     struct {
       short
          h_magic,
          h_dev;
       unsigned short
          h_ino,
          h_mode,
          h_uid,
          h_gid;
       short
          h_nlink,
          h_rdev,
          h_mtime[2],
          h_namesize,
          h_filesize[2];
       char
          h_name[n];         /* described below */
     } Hdr;

When the cpio command is used with the -c flag, the header for the cpio
structure may be read as:

    sscanf(Chdr,"%6ho%6ho%6ho%6ho%6ho%6ho%6ho%6ho%11lo%6ho%11lo%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,
    &Longtime, &Hdr.h_namesize, &Longfile, &Hdr.h_name);

Longtime and Longfile are equivalent to Hdr.h_mtime and Hdr.h_filesize,
respectively.  The contents of each file together with other items describing
the file are recorded in an element of the array of varying length structures.
The member h_magic contains the constant octal 070707 (or 0x71c7).  The stat
system call explains the meaning of structure members h_dev through h_mtime.
The length of the null-terminated path name, h_name, including the null byte is
indicated by n, where n = (h_namesize % 2) + h_namesize.  In other words, n is
equal to h_namesize if h_namesize is even.  If h_namesize is odd, n is equal to
h_namesize + 1.

The last record of the archive always contains the name "TRAILER!!!".
Directories and the trailer are recorded with h_filesize equal to 0.



Processed November 7, 1990         CPIO(5,F)                                  1



CPIO(5,F)                   AIX Technical Reference                   CPIO(5,F)




Directories and special files are treated in a slightly different way.  A
directory is written with a 0 size, meaning no data blocks follow.  Also, if
the directory is a hidden directory, an @ (at) is appended to the name.  A
special file size is also 0; its major/minor device number is stored in the
h_rdev field and its device site number is stored in the h_namesize field.

RELATED INFORMATION

In this book:  "scanf, fscanf, sscanf, NLscanf, NLfscanf, NLsscanf, wsscanf"
and "statx, fstatx, stat, fstat, fullstat, ffullstat, lstat."

The cpio and find commands in AIX Operating System Commands Reference.










































Processed November 7, 1990         CPIO(5,F)                                  2

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