ar(1) — Linux manual page


AR(1)                     GNU Development Tools                    AR(1)

NAME         top

       ar - create, modify, and extract from archives

SYNOPSIS         top

       ar [-X32_64] [-]p[mod] [--plugin name] [--target bfdname]
       [--output dirname] [--record-libdeps libdeps] [--thin] [relpos]
       [count] archive [member...]

DESCRIPTION         top

       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         top

       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

       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

       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

           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

           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.

       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

       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:

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

           Displays the version information of ar and then exits.

           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

           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  For
           Clang based compilations it is called  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.

           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.

           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         top

       nm(1), ranlib(1), and the Info entries for binutils.

COPYRIGHT         top

       Copyright (c) 1991-2023 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

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binutils-2.41                  2023-12-22                          AR(1)

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