|AR(1)||GNU Development Tools||AR(1)|
ar - create, modify, and extract from archives
ar [-X32_64] [-]p[mod [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 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:
If you specify the v modifier, ar lists each module as it is deleted.
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.
If you specify no member arguments, all the files in the archive are printed.
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, the archive's symbol table index is not updated, even if it already existed; you can use ar s or ranlib explicitly to update the symbol table index.
However, too many different systems assume quick append rebuilds the index, so GNU ar implements q as a synonym for r.
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.
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.
If you do not specify a member, all files in the archive are extracted.
A number of modifiers (mod) may immediately follow the p keyletter, to specify variations on an operation's behavior:
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.
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.
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Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 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".