ar(5) File Formats Manual ar(5)
Name
ar - archive (library) file format
Syntax
#include <ar.h>
Description
The archive command, combines several files into one. Archives are used mainly as libraries to be searched by the link-editor,
A file produced by 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>
"
#define SARMAG 8
#define ARFMAG "`
"
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 an even (0 mod 2) boundary; a new-line is inserted between files if necessary. The size given reflects the actual size
of the file exclusive of padding.
Provisions are not made 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.
Restrictions
A filename loses trailing blanks. Most software dealing with archives takes an included blank as a name terminator.
See Also
ar(1), ld(1), nm(1)
RISC ar(5)
