ar(4)ar(4)NAMEar - 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.
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:
COMMON ARCHIVE FORMAT
ARCHIVE File Organization:
_______________________________________________ |__________AR‐
CHIVE_MAGIC_STRING_______________| |__________ARCHIVE_FILE_MEM‐
BER_1______________| | | |
Archive File Header "ar_hdr" |
|.............................................| | Member Contents
| | 1. External symbol directory | | 2.
Text file |
|_____________________________________________| |________AR‐
CHIVE_FILE_MEMBER_2________________| | "ar_hdr"
| |.............................................| | Member Con‐
tents (.o or text file) |
|_____________________________________________| | .
. . | | . . .
| | . . . |
|_____________________________________________| |________AR‐
CHIVE_FILE_MEMBER_n________________| | "ar_hdr"
| |.............................................| | Member
Contents |
|_____________________________________________|
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. 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.
RESTRICTIONS
File names lose trailing blanks. Most software dealing with archives
takes even an included blank as a name terminator.
RELATED INFORMATIONar(1), ld(1), nm(1) delim off
ar(4)
