AR(1) GNU Development Tools AR(1)
NAME
ar - create, modify, and extract from archives
SYNOPSIS
ar [-X32_64] [-]p[mod] [--plugin name] [--target bfdname] [relpos] [count] archive [member...]
DESCRIPTION
The GNU ar program creates, modifies, and extracts from archives. An archive is a single file holding a
collection of other files in a structure that makes it possible to retrieve the original individual files
(called members of the archive).
The original files' contents, mode (permissions), timestamp, owner, and group are preserved in the archive,
and can be restored on extraction.
GNU ar can maintain archives whose members have names of any length; however, depending on how ar is
configured on your system, a limit on member-name length may be imposed for compatibility with archive formats
maintained with other tools. If it exists, the limit is often 15 characters (typical of formats related to
a.out) or 16 characters (typical of formats related to coff).
ar is considered a binary utility because archives of this sort are most often used as libraries holding
commonly needed subroutines.
ar creates an index to the symbols defined in relocatable object modules in the archive when you specify the
modifier s. Once created, this index is updated in the archive whenever ar makes a change to its contents
(save for the q update operation). An archive with such an index speeds up linking to the library, and allows
routines in the library to call each other without regard to their placement in the archive.
You may use nm -s or nm --print-armap to list this index table. If an archive lacks the table, another form
of ar called ranlib can be used to add just the table.
GNU ar can optionally create a thin archive, which contains a symbol index and references to the original
copies of the member files of the archive. This is useful for building libraries for use within a local build
tree, where the relocatable objects are expected to remain available, and copying the contents of each object
would only waste time and space.
An archive can either be thin or it can be normal. It cannot be both at the same time. Once an archive is
created its format cannot be changed without first deleting it and then creating a new archive in its place.
Thin archives are also flattened, so that adding one thin archive to another thin archive does not nest it, as
would happen with a normal archive. Instead the elements of the first archive are added individually to the
second archive.
The paths to the elements of the archive are stored relative to the archive itself. For security reasons
absolute paths and paths with a "/../" component are not allowed.
GNU ar is designed to be compatible with two different facilities. You can control its activity using
command-line options, like the different varieties of ar on Unix systems; or, if you specify the single
command-line option -M, you can control it with a script supplied via standard input, like the MRI "librarian"
program.
OPTIONS
GNU ar allows you to mix the operation code p and modifier flags mod in any order, within the first command-
line argument.
If you wish, you may begin the first command-line argument with a dash.
If no modifiers are used with "m", any members you name in the member arguments are moved to the end of
the archive; you can use the a, b, or i modifiers to move them to a specified place instead.
p Print the specified members of the archive, to the standard output file. If the v modifier is specified,
show the member name before copying its contents to standard output.
If you specify no member arguments, all the files in the archive are printed.
q Quick append; Historically, add the files member... to the end of archive, without checking for
replacement.
The modifiers a, b, and i do not affect this operation; new members are always placed at the end of the
archive.
The modifier v makes ar list each file as it is appended.
Since the point of this operation is speed, implementations of ar have the option of not updating the
archive's symbol table if one exists. Too many different systems however assume that symbol tables are
always up-to-date, so GNU ar will rebuild the table even with a quick append.
Note - GNU ar treats the command qs as a synonym for r - replacing already existing files in the archive
and appending new ones at the end.
r Insert the files member... into archive (with replacement). This operation differs from q in that any
previously existing members are deleted if their names match those being added.
If one of the files named in member... does not exist, ar displays an error message, and leaves
undisturbed any existing members of the archive matching that name.
By default, new members are added at the end of the file; but you may use one of the modifiers a, b, or i
to request placement relative to some existing member.
The modifier v used with this operation elicits a line of output for each file inserted, along with one of
the letters a or r to indicate whether the file was appended (no old member deleted) or replaced.
s Add an index to the archive, or update it if it already exists. Note this command is an exception to the
rule that there can only be one command letter, as it is possible to use it as either a command or a
modifier. In either case it does the same thing.
t Display a table listing the contents of archive, or those of the files listed in member... that are
present in the archive. Normally only the member name is shown; if you also want to see the modes
(permissions), timestamp, owner, group, and size, you can request that by also specifying the v modifier.
If you do not specify a member, all files in the archive are listed.
If there is more than one file with the same name (say, fie) in an archive (say b.a), ar t b.a fie lists
only the first instance; to see them all, you must ask for a complete listing---in our example, ar t b.a.
x Extract members (named member) from the archive. You can use the v modifier with this operation, to
request that ar list each name as it extracts it.
If you do not specify a member, all files in the archive are extracted.
archive member must be present as the relpos argument, before the archive specification.
b Add new files before an existing member of the archive. If you use the modifier b, the name of an
existing archive member must be present as the relpos argument, before the archive specification. (same
as i).
c Create the archive. The specified archive is always created if it did not exist, when you request an
update. But a warning is issued unless you specify in advance that you expect to create it, by using this
modifier.
D Operate in deterministic mode. When adding files and the archive index use zero for UIDs, GIDs,
timestamps, and use consistent file modes for all files. When this option is used, if ar is used with
identical options and identical input files, multiple runs will create identical output files regardless
of the input files' owners, groups, file modes, or modification times.
If binutils was configured with --enable-deterministic-archives, then this mode is on by default. It can
be disabled with the U modifier, below.
f Truncate names in the archive. GNU ar will normally permit file names of any length. This will cause it
to create archives which are not compatible with the native ar program on some systems. If this is a
concern, the f modifier may be used to truncate file names when putting them in the archive.
i Insert new files before an existing member of the archive. If you use the modifier i, the name of an
existing archive member must be present as the relpos argument, before the archive specification. (same
as b).
l This modifier is accepted but not used.
N Uses the count parameter. This is used if there are multiple entries in the archive with the same name.
Extract or delete instance count of the given name from the archive.
o Preserve the original dates of members when extracting them. If you do not specify this modifier, files
extracted from the archive are stamped with the time of extraction.
P Use the full path name when matching names in the archive. GNU ar can not create an archive with a full
path name (such archives are not POSIX complaint), but other archive creators can. This option will cause
GNU ar to match file names using a complete path name, which can be convenient when extracting a single
file from an archive created by another tool.
s Write an object-file index into the archive, or update an existing one, even if no other change is made to
the archive. You may use this modifier flag either with any operation, or alone. Running ar s on an
archive is equivalent to running ranlib on it.
S Do not generate an archive symbol table. This can speed up building a large library in several steps.
The resulting archive can not be used with the linker. In order to build a symbol table, you must omit
the S modifier on the last execution of ar, or you must run ranlib on the archive.
T Make the specified archive a thin archive. If it already exists and is a regular archive, the existing
members must be present in the same directory as archive.
u Normally, ar r... inserts all files listed into the archive. If you would like to insert only those of
the files you list that are newer than existing members of the same names, use this modifier. The u
modifier is allowed only for the operation r (replace). In particular, the combination qu is not allowed,
since checking the timestamps would lose any speed advantage from the operation q.
is the default for GNU ar. ar does not support any of the other -X options; in particular, it does not
support -X32 which is the default for AIX ar.
The optional command line switch --plugin name causes ar to load the plugin called name which adds support for
more file formats. This option is only available if the toolchain has been built with plugin support enabled.
The optional command line switch --target bfdname specifies that the archive members are in an object code
format different from your system's default format. See
@file
Read command-line options from file. The options read are inserted in place of the original @file option.
If file does not exist, or cannot be read, then the option will be treated literally, and not removed.
Options in file are separated by whitespace. A whitespace character may be included in an option by
surrounding the entire option in either single or double quotes. Any character (including a backslash)
may be included by prefixing the character to be included with a backslash. The file may itself contain
additional @file options; any such options will be processed recursively.
SEE ALSO
nm(1), ranlib(1), and the Info entries for binutils.
COPYRIGHT
Copyright (c) 1991-2014 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free
Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no
Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is
included in the section entitled "GNU Free Documentation License".
binutils-2.25 2014-12-23 AR(1)
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