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AR(5) File Formats Manual AR(5) 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: /*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1991, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * All or some portions of this file are derived from material licensed * to the University of California by American Telephone and Telegraph * Co. or Unix System Laboratories, Inc. and are reproduced herein with * the permission of UNIX System Laboratories, Inc. * * This code is derived from software contributed to Berkeley by * Hugh Smith at The University of Guelph. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)ar.h8.2 (Berkeley) 1/21/94 */ #ifndef _AR_H_ #define _AR_H_ #include <sys/cdefs.h> /* Pre-4BSD archives had these magic numbers in them. */ #define OARMAG10177555 #define OARMAG20177545 #define ARMAG "!<arch>0/* ar "magic number" */ #define SARMAG8/* strlen(ARMAG); */ #define AR_EFMT1"#1/"/* extended format #1 */ struct ar_hdr { char ar_name[16];/* name */ char ar_date[12];/* modification time */ char ar_uid[6];/* user id */ char ar_gid[6];/* group id */ char ar_mode[8];/* octal file permissions */ char ar_size[10];/* size in bytes */ #define ARFMAG"`0 char ar_fmag[2];/* consistency check */ } __packed; #endif /* !_AR_H_ */ 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 pat- tern per chmod(2); the size is counted in bytes. Each file begins on a word boundary; 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. SEE ALSO ar(1), ld(1), nm(1) BUGS Coding user and group IDs as characters is a botch. AR(5)