f78 ar Contents|Index|Previous|Next

ar

ar [-]p[mod [relpos]] archive [member ...]
ar -M [ <mri-script ]

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 only 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.

Controlling ar on the command line

ar [-]p[mod [relpos]] archive [member ...]

When you use ar in the Unix style, ar insists on at least two arguments to execute: one keyletter specifying the operation (optionally accompanied by other keyletters specifying modifiers), and the archive name to act on.

Most operations can also accept further member arguments, specifying particular files to operate on.

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.

0