ar [-X32_64] [-]p[mod [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
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, 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".
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.
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.
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.
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.
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.
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.
SEE ALSO
nm(1),
ranlib(1), and the Info entries
for binutils.
Important:
Use the man command (% man) to see how a command is used on your
particular computer.
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