term% cat index.txt AR(6) Games Manual AR(6)
NAME
ar - archive (library) file format
SYNOPSIS
#include <ar.h>
DESCRIPTION
The archive command ar(1) is used to combine several files into one.
Archives are used mainly as libraries to be searched by the loaders
2l(1) et al.
A file produced by ar has a magic string at the start, followed by the
constituent files, each preceded by a file header. The magic number
and header layout as described in the include file are:
#define ARMAG "!<arch>\n"
#define SARMAG 8
#define ARFMAG "`\n"
struct ar_hdr {
char name[16];
char date[12];
char uid[6];
char gid[6];
char mode[8];
char size[10];
char fmag[2];
};
#define SAR_HDR 60
The name is a blank-padded string. The field contains to help verify
the presence of a header. The other fields are left-adjusted, blank-
padded numbers. They are decimal except for which is octal. The date
is the modification date of the file (see stat(2)) at the time of its
insertion into the archive. The mode is the low 9 bits of the file
permission mode. The length of the header is Because the structure is
padded in an architecture-dependent manner, the structure should never
be read or written as a unit; instead, each field should be read or
written independently.
Each file begins on an even (0 mod 2) boundary; a newline is inserted
between files if necessary. Nevertheless size reflects the actual size
of the file exclusive of padding.
When all members of an archive are object files of the same architec‐
ture, ar automatically adds an extra file, named __.SYMDEF, as the
first member of the archive. This file contains an index used by the
loaders to locate all externally defined text and data symbols in the
archive.
There is no provision for empty areas in an archive file.
SEE ALSO
ar(1), 2l(1), nm(1), stat(2)
BUGS
The uid and gid fields are unused in Plan 9. They provide compatibil‐
ity with Unix ar format.
AR(6)