AR(4)                    DOMAIN/IX SYS5                     AR(4)



NAME
     ar - common archive file format

USAGE
     #include <ar.h>

DESCRIPTION
     The archive command ar(1) is used to combine several files
     into one.  Archives are used mainly as libraries for the
     link editor ld(1) to search.

     Each archive begins with the archive magic string.

       #define ARMAG       "!<arch>\n"/* magic string */
       #define SARMAG      8         /* length of magic string */


     Each archive that contains common object files (see
     a.out(4)) includes an archive symbol table.  The link editor
     ld uses this table to determine which archive members must
     be loaded during the link edit process.  The archive symbol
     table (if it exists) is always the first file in the
     archive.  It is never listed, and is automatically created
     and/or updated by ar.

     Archive file members follow the magic string.  Each file
     member is preceded by a file member header which has the
     following format:

       #define ARFMAG      "`\n"/* header trailer string */

       struct ar_hdr       /* file member header */
       {
         char ar_name[16]; /* '/' terminated file member name */
         char ar_date[12]; /* file member date */
         char ar_uid[6];   /* file member user identification */
         char ar_gid[6];   /* file member group identification */
         char ar_mode[8];  /* file member mode (octal) */
         char ar_size[10]; /* file member size */
         char ar_fmag[2];  /* header trailer string */
       };


     All information in the file member headers is in printable
     ASCII.  The numeric information contained in the headers is
     stored in the form of decimal numbers (except for ar_mode,
     which is in octal).  Thus, if the archive contains printable
     files, the archive itself is printable.





Printed 12/4/86                                              AR-1

AR(4)                    DOMAIN/IX SYS5                     AR(4)



     The ar_name field is blank-padded and ends with a slash (/).
     The ar_date field is the file's last modification date (at
     the time of its insertion into the archive).  Common format
     archives can be moved from system to system as long as the
     portable archive command ar is used.  Conversion tools like
     arcv(1) and convert(1) help to convert archives from other
     formats to this format.

     Each member file of an archive file begins on an even byte
     boundary.  A newline is inserted between member files, if
     necessary.  Nevertheless, the size given reflects the actual
     size of the file, exclusive of padding.

     There is no provision for empty areas in an archive file.

     If the archive symbol table exists, the first file in the
     archive has a zero length name (i.e., ar_name[0] == '/').
     The contents of this file are as follows:

     ⊕  The number of symbols.  Length: 4 bytes.

     ⊕  The array of offsets into the archive file.  Length: 4
        bytes * "the number of symbols".

     ⊕  The name string table.  Length: ar_size - (4 bytes *
        ("the number of symbols" + 1)).

     The number of symbols and the array of offsets are managed
     with sgetl and sputl.  The string table contains exactly as
     many null terminated strings as there are elements in the
     array of offsets.  Each offset from the array is associated
     with the corresponding name from the string table (in
     order).  The names in the string table are all the defined
     global symbols found in the common object files in the
     archive.  Each offset is the location of the archive header
     for the associated symbol.

NOTES
     Strip(1) will remove all archive symbol entries from the
     header.  The archive symbol entries must be restored with
     the ts option of the ar command before the archive can be
     used with the link editor ld.

RELATED INFORMATION
     ar(1), arcv(1), convert(1), ld(1), strip(1), sputl(3X)








AR-2                                              Printed 12/4/86