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] [--output
dirname] [--record-libdeps libdeps] [--thin] [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. 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.
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.
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.
SEE ALSO
nm(1), ranlib(1), and the Info entries for binutils.
COPYRIGHT
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".
binutils-2.44 2025-03-03 AR(1)
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