AR(1) GNU Development Tools AR(1)
ar - create, modify, and extract from archives
ar [--plugin name] [-X32_64] [-]p[mod [relpos] [count]] [--target bfdname] archive
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.
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.
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.
The p keyletter specifies what operation to execute; it may be any of the following, but
you must specify only one of them:
d Delete modules from the archive. Specify the names of modules to be deleted as
member...; the archive is untouched if you specify no files to delete.
If you specify the v modifier, ar lists each module as it is deleted.
m Use this operation to move members in an archive.
The ordering of members in an archive can make a difference in how programs are linked
using the library, if a symbol is defined in more than one member.
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
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, the archive's symbol table index is not
updated, even if it already existed; you can use ar s or ranlib explicitly to update
the symbol table index.
However, too many different systems assume quick append rebuilds the index, so GNU ar
implements q as a synonym for r.
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
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.
Files cannot be extracted from a thin archive.
Displays the list of command line options supported by ar and then exits.
Displays the version information of ar and then exits.
A number of modifiers (mod) may immediately follow the p keyletter, to specify variations
on an operation's behavior:
a Add new files after an existing member of the archive. If you use the modifier a, the
name of an existing archive member must be present as the relpos argument, before the
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
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
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
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.
U Do not operate in deterministic mode. This is the inverse of the D modifier, above:
added files and the archive index will get their actual UID, GID, timestamp, and file
This is the default unless binutils was configured with
v This modifier requests the verbose version of an operation. Many operations display
additional information, such as filenames processed, when the modifier v is appended.
V This modifier shows the version number of ar.
ar ignores an initial option spelt -X32_64, for compatibility with AIX. The behaviour
produced by this option 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
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.
nm(1), ranlib(1), and the Info entries for binutils.
Copyright (c) 1991-2013 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
binutils-126.96.36.199.1 2014-06-10 AR(1)