ar(5)
NAME
ar − archive (library) file format
SYNTAX
#include <ar.h>
DESCRIPTION
The ar command 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:
#define ARMAG 0177545
struct ar_hdr {
char ar_name[14];
long ar_date;
char ar_uid;
char ar_gid;
int ar_mode;
long ar_size;
};
The name is a null-terminated string. The date is in the form of time(2). The user ID and group ID are numbers. The mode is a bit pattern per chmod(2). The size is counted in bytes.
Each file begins on a word boundary and a null byte is inserted between files if necessary. Nevertheless the size given reflects the actual size of the file exclusive of padding.
Notice there is no provision for empty areas in an archive file.
RESTRICTIONS
Coding user and group IDs as characters is a botch.