ar Man page

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.

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; 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.

–help
Displays the list of command line options supported by ar and then
exits.

–version
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 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.

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.

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

@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, ranlib, and the Info entries for binutils.

COPRYRIGHT

Copyright (c) 1991-2015 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-2.26.1 2016-06-29 AR(1)