NAME
ar - archive (library) file format

SYNOPSIS
#include <ar.h>

DESCRIPTION
The archive command ar combines several files into one. Archives
are used mainly as libraries to be searched by the link-editor
ld(1).

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>0
#define SARMAG 8

#define ARFMAG "‘0

struct ar_hdr {
char ar_name[16];
char ar_date[12];
char ar_uid[6];
char ar_gid[6];
char ar_mode[8];
char ar_size[10];
char ar_fmag[2];
};

The name is a blank-padded string. The ar_fmag field contains
ARFMAG to help verify the presence of a header. The other fields
are left-adjusted, blank-padded numbers. They are decimal except
for ar_mode, which is octal. The date is the modification date of
the file at the time of its insertion into the archive.

Each file begins on a even (0 mod 2) boundary; a new-line is
inserted between 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.

The encoding of the header is portable across machines. If an
archive contains printable files, the archive itself is printable.

SEE ALSO
ar(1), ld(1), nm(1)

BUGS
File names lose trailing blanks. Most software dealing with
archives takes even an included blank as a name terminator.