ar






ar − create, modify, and extract from archives

ar [−X32_64] []p[mod] [−−plugin name] [−−target bfdname]
[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.

     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.











                             ‐2‐


     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.











                             ‐3‐


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.










                             ‐4‐


    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.

     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









                             ‐5‐


    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,









                             ‐6‐


    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 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.

−−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.










                             ‐7‐


−−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

@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) 1991−2018 Free Software Foundation, Inc.

     Permission is granted to copy, distribute and/or modify
this document under the terms of the GNU Free Documentation
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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".