NAME

ar − archive (library) file format

SYNOPSIS

#include <ar.h>

DESCRIPTION

The archive command ar is used to combine 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 number 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:

#defineARFMAG0177545
structar_hdr {
charar_name[14];
longar_date;
shortar_uid;
shortar_gid;
shortar_mode;
longar_size;
};

The "ar_fmag" field contains the 32-bit number ARFMAG to help verify the presence of a header.  The name is a blank padded string.  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. 

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. 

7th Edition  —  1/5/82