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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | SEE ALSO | COPYRIGHT | COLOPHON |
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AR(1) GNU Development Tools AR(1)
ar - create, modify, and extract from archives
ar [-X32_64] [-]p[mod] [--plugin name] [--target bfdname]
[--output dirname] [--record-libdeps libdeps] [--thin] [relpos]
[count] archive [member...]
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. Since libraries often will depend on other
libraries, ar can also record the dependencies of a library when
the --record-libdeps option is specified.
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 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, but if the modifier O
is specified, then the corresponding offset of the member is
also displayed. Finally, in order to see the modes
(permissions), timestamp, owner, group, and size the v
modifier should be included.
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, and there are
restrictions on extracting from archives created with P: The
paths must not be absolute, may not contain "..", and any
subdirectories in the paths must exist. If it is desired to
avoid these restrictions then used the --output option to
specify an output directory.
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 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 Specify dependencies of this library. The dependencies must
immediately follow this option character, must use the same
syntax as the linker command line, and must be specified
within a single argument. I.e., if multiple items are needed,
they must be quoted to form a single command line argument.
For example l "-L/usr/local/lib -lmydep1 -lmydep2"
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.
O Display member offsets inside the archive. Use together with
the t option.
P Use the full path name when matching or storing names in the
archive. Archives created with full path names are not POSIX
compliant, and thus may not work with tools other than up to
date GNU tools. Modifying such archives with GNU ar without
using P will remove the full path names unless the archive is
a thin archive. Note that P may be useful when adding files
to a thin archive since r without P ignores the path when
choosing which element to replace. Thus
ar rcST archive.a subdir/file1 subdir/file2 file1
will result in the first "subdir/file1" being replaced with
"file1" from the current directory. Adding P will prevent
this replacement.
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 Deprecated alias for --thin. T is not recommended because in
many ar implementations T has a different meaning, as
specified by X/Open System Interface.
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.
Note - if an archive has been created in a deterministic
manner, eg via the use of the D modifier, then replacement
will always happen and the u modifier will be ineffective.
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 mode values.
This is the default unless binutils was configured with
--enable-deterministic-archives.
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.
The ar program also supports some command-line options which are
neither modifiers nor actions, but which do change its behaviour
in specific ways:
--help
Displays the list of command-line options supported by ar and
then exits.
--version
Displays the version information of ar and then exits.
-X32_64
ar ignores an initial option spelled -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.
--plugin name
The optional command-line switch --plugin name causes ar to
load the plugin called name which adds support for more file
formats, including object files with link-time optimization
information.
This option is only available if the toolchain has been built
with plugin support enabled.
If --plugin is not provided, but plugin support has been
enabled then ar iterates over the files in
${libdir}/bfd-plugins in alphabetic order and the first plugin
that claims the object in question is used.
Please note that this plugin search directory is not the one
used by ld's -plugin option. In order to make ar use the
linker plugin it must be copied into the ${libdir}/bfd-plugins
directory. For GCC based compilations the linker plugin is
called liblto_plugin.so.0.0.0. For Clang based compilations
it is called LLVMgold.so. The GCC plugin is always backwards
compatible with earlier versions, so it is sufficient to just
copy the newest one.
--target target
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
--output dirname
The --output option can be used to specify a path to a
directory into which archive members should be extracted. If
this option is not specified then the current directory will
be used.
Note - although the presence of this option does imply a x
extraction operation that option must still be included on the
command line.
--record-libdeps libdeps
The --record-libdeps option is identical to the l modifier,
just handled in long form.
--thin
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.
@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.
nm(1), ranlib(1), and the Info entries for binutils.
Copyright (c) 1991-2025 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".
This page is part of the binutils (a collection of tools for
working with executable binaries) project. Information about the
project can be found at ⟨http://www.gnu.org/software/binutils/⟩.
If you have a bug report for this manual page, see
⟨http://sourceware.org/bugzilla/enter_bug.cgi?product=binutils⟩.
This page was obtained from the tarball binutils-with-
gold-2.44.tar.gz fetched from ⟨https://ftp.gnu.org/gnu/binutils/⟩
on 2025-08-11. If you discover any rendering problems in this
HTML version of the page, or you believe there is a better or more
up-to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
binutils-2.44 2025-08-11 AR(1)
Pages that refer to this page: ld(1), nm(1), ranlib(1), size(1), strings(1), uselib(2)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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