\input texinfo @c -*- Texinfo -*-

@setfilename binutils.info

@settitle @sc{gnu} Binary Utilities

@finalout

@synindex ky cp

@c man begin INCLUDE

@include bfdver.texi

@c man end

@copying

@c man begin COPYRIGHT

Copyright @copyright{} 1991-2016 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 License''.

@c man end

@end copying

@dircategory Software development

@direntry

* Binutils: (binutils). The GNU binary utilities.

@end direntry

@dircategory Individual utilities

@direntry

* addr2line: (binutils)addr2line. Convert addresses to file and line.

* ar: (binutils)ar. Create, modify, and extract from archives.

* c++filt: (binutils)c++filt. Filter to demangle encoded C++ symbols.

* cxxfilt: (binutils)c++filt. MS-DOS name for c++filt.

* dlltool: (binutils)dlltool. Create files needed to build and use DLLs.

* nlmconv: (binutils)nlmconv. Converts object code into an NLM.

* nm: (binutils)nm. List symbols from object files.

* objcopy: (binutils)objcopy. Copy and translate object files.

* objdump: (binutils)objdump. Display information from object files.

* ranlib: (binutils)ranlib. Generate index to archive contents.

* readelf: (binutils)readelf. Display the contents of ELF format files.

* size: (binutils)size. List section sizes and total size.

* strings: (binutils)strings. List printable strings from files.

* strip: (binutils)strip. Discard symbols.

* elfedit: (binutils)elfedit. Update the ELF header of ELF files.

* windmc: (binutils)windmc. Generator for Windows message resources.

* windres: (binutils)windres. Manipulate Windows resources.

@end direntry

@titlepage

@title The @sc{gnu} Binary Utilities

@ifset VERSION_PACKAGE

@subtitle @value{VERSION_PACKAGE}

@end ifset

@subtitle Version @value{VERSION}

@sp 1

@subtitle @value{UPDATED}

@author Roland H. Pesch

@author Jeffrey M. Osier

@author Cygnus Support

@page

@tex

{\parskip=0pt \hfill Cygnus Support\par \hfill

Texinfo \texinfoversion\par }

@end tex

@vskip 0pt plus 1filll

@insertcopying

@end titlepage

@contents

@node Top

@top Introduction

@cindex version

This brief manual contains documentation for the @sc{gnu} binary

utilities

@ifset VERSION_PACKAGE

@value{VERSION_PACKAGE}

@end ifset

version @value{VERSION}:

@iftex

@table @code

@item ar

Create, modify, and extract from archives

@item nm

List symbols from object files

@item objcopy

Copy and translate object files

@item objdump

Display information from object files

@item ranlib

Generate index to archive contents

@item readelf

Display the contents of ELF format files.

@item size

List file section sizes and total size

@item strings

List printable strings from files

@item strip

Discard symbols

@item elfedit

Update the ELF header of ELF files.

@item c++filt

Demangle encoded C++ symbols (on MS-DOS, this program is named

@code{cxxfilt})

@item addr2line

Convert addresses into file names and line numbers

@item nlmconv

Convert object code into a Netware Loadable Module

@item windres

Manipulate Windows resources

@item windmc

Generator for Windows message resources

@item dlltool

Create the files needed to build and use Dynamic Link Libraries

@end table

@end iftex

This document is distributed under the terms of the GNU Free

Documentation License version 1.3. A copy of the license is included

in the section entitled ``GNU Free Documentation License''.

@menu

* ar:: Create, modify, and extract from archives

* nm:: List symbols from object files

* objcopy:: Copy and translate object files

* objdump:: Display information from object files

* ranlib:: Generate index to archive contents

* size:: List section sizes and total size

* strings:: List printable strings from files

* strip:: Discard symbols

* c++filt:: Filter to demangle encoded C++ symbols

* cxxfilt: c++filt. MS-DOS name for c++filt

* addr2line:: Convert addresses to file and line

* nlmconv:: Converts object code into an NLM

* windmc:: Generator for Windows message resources

* windres:: Manipulate Windows resources

* dlltool:: Create files needed to build and use DLLs

* readelf:: Display the contents of ELF format files

* elfedit:: Update the ELF header of ELF files

* Common Options:: Command-line options for all utilities

* Selecting the Target System:: How these utilities determine the target

* Reporting Bugs:: Reporting Bugs

* GNU Free Documentation License:: GNU Free Documentation License

* Binutils Index:: Binutils Index

@end menu

@node ar

@chapter ar

@kindex ar

@cindex archives

@cindex collections of files

@c man title ar create, modify, and extract from archives

@smallexample

ar [-]@var{p}[@var{mod}] [@option{--plugin} @var{name}] [@option{--target} @var{bfdname}] [@var{relpos}] [@var{count}] @var{archive} [@var{member}@dots{}]

ar -M [ <mri-script ]

@end smallexample

@c man begin DESCRIPTION ar

The @sc{gnu} @command{ar} program creates, modifies, and extracts from

archives. An @dfn{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 @dfn{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.

@cindex name length

@sc{gnu} @command{ar} can maintain archives whose members have names of any

length; however, depending on how @command{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).

@cindex libraries

@command{ar} is considered a binary utility because archives of this sort

are most often used as @dfn{libraries} holding commonly needed

subroutines.

@cindex symbol index

@command{ar} creates an index to the symbols defined in relocatable

object modules in the archive when you specify the modifier @samp{s}.

Once created, this index is updated in the archive whenever @command{ar}

makes a change to its contents (save for the @samp{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 @samp{nm -s} or @samp{nm --print-armap} to list this index

table. If an archive lacks the table, another form of @command{ar} called

@command{ranlib} can be used to add just the table.

@cindex thin archives

@sc{gnu} @command{ar} can optionally create a @emph{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 @emph{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 @emph{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.

@cindex compatibility, @command{ar}

@cindex @command{ar} compatibility

@sc{gnu} @command{ar} is designed to be compatible with two different

facilities. You can control its activity using command-line options,

like the different varieties of @command{ar} on Unix systems; or, if you

specify the single command-line option @option{-M}, you can control it

with a script supplied via standard input, like the MRI ``librarian''

program.

@c man end

@menu

* ar cmdline:: Controlling @command{ar} on the command line

* ar scripts:: Controlling @command{ar} with a script

@end menu

@page

@node ar cmdline

@section Controlling @command{ar} on the Command Line

@smallexample

@c man begin SYNOPSIS ar

ar [@option{-X32_64}] [@option{-}]@var{p}[@var{mod}] [@option{--plugin} @var{name}] [@option{--target} @var{bfdname}] [@var{relpos}] [@var{count}] @var{archive} [@var{member}@dots{}]

@c man end

@end smallexample

@cindex Unix compatibility, @command{ar}

When you use @command{ar} in the Unix style, @command{ar} insists on at least two

arguments to execute: one keyletter specifying the @emph{operation}

(optionally accompanied by other keyletters specifying

@emph{modifiers}), and the archive name to act on.

Most operations can also accept further @var{member} arguments,

specifying particular files to operate on.

@c man begin OPTIONS ar

@sc{gnu} @command{ar} allows you to mix the operation code @var{p} and modifier

flags @var{mod} in any order, within the first command-line argument.

If you wish, you may begin the first command-line argument with a

dash.

@cindex operations on archive

The @var{p} keyletter specifies what operation to execute; it may be

any of the following, but you must specify only one of them:

@table @samp

@item d

@cindex deleting from archive

@emph{Delete} modules from the archive. Specify the names of modules to

be deleted as @var{member}@dots{}; the archive is untouched if you

specify no files to delete.

If you specify the @samp{v} modifier, @command{ar} lists each module

as it is deleted.

@item m

@cindex moving in archive

Use this operation to @emph{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 @code{m}, any members you name in the

@var{member} arguments are moved to the @emph{end} of the archive;

you can use the @samp{a}, @samp{b}, or @samp{i} modifiers to move them to a

specified place instead.

@item p

@cindex printing from archive

@emph{Print} the specified members of the archive, to the standard

output file. If the @samp{v} modifier is specified, show the member

name before copying its contents to standard output.

If you specify no @var{member} arguments, all the files in the archive are

printed.

@item q

@cindex quick append to archive

@emph{Quick append}; Historically, add the files @var{member}@dots{} to the end of

@var{archive}, without checking for replacement.

The modifiers @samp{a}, @samp{b}, and @samp{i} do @emph{not} affect this

operation; new members are always placed at the end of the archive.

The modifier @samp{v} makes @command{ar} list each file as it is appended.

Since the point of this operation is speed, implementations of

@command{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 @sc{gnu} @command{ar} will

rebuild the table even with a quick append.

Note - @sc{gnu} @command{ar} treats the command @samp{qs} as a

synonym for @samp{r} - replacing already existing files in the

archive and appending new ones at the end.

@item r

@cindex replacement in archive

Insert the files @var{member}@dots{} into @var{archive} (with

@emph{replacement}). This operation differs from @samp{q} in that any

previously existing members are deleted if their names match those being

added.

If one of the files named in @var{member}@dots{} does not exist, @command{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 @samp{a}, @samp{b}, or @samp{i} to request

placement relative to some existing member.

The modifier @samp{v} used with this operation elicits a line of

output for each file inserted, along with one of the letters @samp{a} or

@samp{r} to indicate whether the file was appended (no old member

deleted) or replaced.

@item s

@cindex ranlib

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.

@item t

@cindex contents of archive

Display a @emph{table} listing the contents of @var{archive}, or those

of the files listed in @var{member}@dots{} 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 @samp{v} modifier.

If you do not specify a @var{member}, all files in the archive

are listed.

@cindex repeated names in archive

@cindex name duplication in archive

If there is more than one file with the same name (say, @samp{fie}) in

an archive (say @samp{b.a}), @samp{ar t b.a fie} lists only the

first instance; to see them all, you must ask for a complete

listing---in our example, @samp{ar t b.a}.

@c WRS only; per Gumby, this is implementation-dependent, and in a more

@c recent case in fact works the other way.

@item x

@cindex extract from archive

@emph{Extract} members (named @var{member}) from the archive. You can

use the @samp{v} modifier with this operation, to request that

@command{ar} list each name as it extracts it.

If you do not specify a @var{member}, all files in the archive

are extracted.

Files cannot be extracted from a thin archive.

@item --help

Displays the list of command line options supported by @command{ar}

and then exits.

@item --version

Displays the version information of @command{ar} and then exits.

@end table

A number of modifiers (@var{mod}) may immediately follow the @var{p}

keyletter, to specify variations on an operation's behavior:

@table @samp

@item a

@cindex relative placement in archive

Add new files @emph{after} an existing member of the

archive. If you use the modifier @samp{a}, the name of an existing archive

member must be present as the @var{relpos} argument, before the

@var{archive} specification.

@item b

Add new files @emph{before} an existing member of the

archive. If you use the modifier @samp{b}, the name of an existing archive

member must be present as the @var{relpos} argument, before the

@var{archive} specification. (same as @samp{i}).

@item c

@cindex creating archives

@emph{Create} the archive. The specified @var{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.

@item D

@cindex deterministic archives

@kindex --enable-deterministic-archives

Operate in @emph{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 @command{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 @file{binutils} was configured with

@option{--enable-deterministic-archives}, then this mode is on by default.

It can be disabled with the @samp{U} modifier, below.

@item f

Truncate names in the archive. @sc{gnu} @command{ar} will normally permit file

names of any length. This will cause it to create archives which are

not compatible with the native @command{ar} program on some systems. If

this is a concern, the @samp{f} modifier may be used to truncate file

names when putting them in the archive.

@item i

Insert new files @emph{before} an existing member of the

archive. If you use the modifier @samp{i}, the name of an existing archive

member must be present as the @var{relpos} argument, before the

@var{archive} specification. (same as @samp{b}).

@item l

This modifier is accepted but not used.

@c whaffor ar l modifier??? presumably compat; with

@c what???---doc@@cygnus.com, 25jan91

@item N

Uses the @var{count} parameter. This is used if there are multiple

entries in the archive with the same name. Extract or delete instance

@var{count} of the given name from the archive.

@item o

@cindex dates in archive

Preserve the @emph{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.

@item P

Use the full path name when matching names in the archive. @sc{gnu}

@command{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 @sc{gnu} @command{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.

@item s

@cindex writing archive index

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 @samp{ar s} on an

archive is equivalent to running @samp{ranlib} on it.

@item S

@cindex not writing archive index

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

@samp{S} modifier on the last execution of @samp{ar}, or you must run

@samp{ranlib} on the archive.

@item T

@cindex creating thin archive

Make the specified @var{archive} a @emph{thin} archive. If it already

exists and is a regular archive, the existing members must be present

in the same directory as @var{archive}.

@item u

@cindex updating an archive

Normally, @samp{ar r}@dots{} inserts all files

listed into the archive. If you would like to insert @emph{only} those

of the files you list that are newer than existing members of the same

names, use this modifier. The @samp{u} modifier is allowed only for the

operation @samp{r} (replace). In particular, the combination @samp{qu} is

not allowed, since checking the timestamps would lose any speed

advantage from the operation @samp{q}.

@item U

@cindex deterministic archives

@kindex --enable-deterministic-archives

Do @emph{not} operate in @emph{deterministic} mode. This is the inverse

of the @samp{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 @file{binutils} was configured with

@option{--enable-deterministic-archives}.

@item v

This modifier requests the @emph{verbose} version of an operation. Many

operations display additional information, such as filenames processed,

when the modifier @samp{v} is appended.

@item V

This modifier shows the version number of @command{ar}.

@end table

@command{ar} ignores an initial option spelt @samp{-X32_64}, for

compatibility with AIX. The behaviour produced by this option is the

default for @sc{gnu} @command{ar}. @command{ar} does not support any of the other

@samp{-X} options; in particular, it does not support @option{-X32}

which is the default for AIX @command{ar}.

The optional command line switch @option{--plugin} @var{name} causes

@command{ar} to load the plugin called @var{name} which adds support

for more file formats. This option is only available if the toolchain

has been built with plugin support enabled.

The optional command line switch @option{--target} @var{bfdname}

specifies that the archive members are in an object code format

different from your system's default format. See

@xref{Target Selection}, for more information.

@c man end

@ignore

@c man begin SEEALSO ar

nm(1), ranlib(1), and the Info entries for @file{binutils}.

@c man end

@end ignore

@node ar scripts

@section Controlling @command{ar} with a Script

@smallexample

ar -M [ <@var{script} ]

@end smallexample

@cindex MRI compatibility, @command{ar}

@cindex scripts, @command{ar}

If you use the single command-line option @samp{-M} with @command{ar}, you

can control its operation with a rudimentary command language. This

form of @command{ar} operates interactively if standard input is coming

directly from a terminal. During interactive use, @command{ar} prompts for

input (the prompt is @samp{AR >}), and continues executing even after

errors. If you redirect standard input to a script file, no prompts are

issued, and @command{ar} abandons execution (with a nonzero exit code)

on any error.

The @command{ar} command language is @emph{not} designed to be equivalent

to the command-line options; in fact, it provides somewhat less control

over archives. The only purpose of the command language is to ease the

transition to @sc{gnu} @command{ar} for developers who already have scripts

written for the MRI ``librarian'' program.

The syntax for the @command{ar} command language is straightforward:

@itemize @bullet

@item

commands are recognized in upper or lower case; for example, @code{LIST}

is the same as @code{list}. In the following descriptions, commands are

shown in upper case for clarity.

@item

a single command may appear on each line; it is the first word on the

line.

@item

empty lines are allowed, and have no effect.

@item

comments are allowed; text after either of the characters @samp{*}

or @samp{;} is ignored.

@item

Whenever you use a list of names as part of the argument to an @command{ar}

command, you can separate the individual names with either commas or

blanks. Commas are shown in the explanations below, for clarity.

@item

@samp{+} is used as a line continuation character; if @samp{+} appears

at the end of a line, the text on the following line is considered part

of the current command.

@end itemize

Here are the commands you can use in @command{ar} scripts, or when using

@command{ar} interactively. Three of them have special significance:

@code{OPEN} or @code{CREATE} specify a @dfn{current archive}, which is

a temporary file required for most of the other commands.

@code{SAVE} commits the changes so far specified by the script. Prior

to @code{SAVE}, commands affect only the temporary copy of the current

archive.

@table @code

@item ADDLIB @var{archive}

@itemx ADDLIB @var{archive} (@var{module}, @var{module}, @dots{} @var{module})

Add all the contents of @var{archive} (or, if specified, each named

@var{module} from @var{archive}) to the current archive.

Requires prior use of @code{OPEN} or @code{CREATE}.

@item ADDMOD @var{member}, @var{member}, @dots{} @var{member}

@c FIXME! w/Replacement?? If so, like "ar r @var{archive} @var{names}"

@c else like "ar q..."

Add each named @var{member} as a module in the current archive.

Requires prior use of @code{OPEN} or @code{CREATE}.

@item CLEAR

Discard the contents of the current archive, canceling the effect of

any operations since the last @code{SAVE}. May be executed (with no

effect) even if no current archive is specified.

@item CREATE @var{archive}

Creates an archive, and makes it the current archive (required for many

other commands). The new archive is created with a temporary name; it

is not actually saved as @var{archive} until you use @code{SAVE}.

You can overwrite existing archives; similarly, the contents of any

existing file named @var{archive} will not be destroyed until @code{SAVE}.

@item DELETE @var{module}, @var{module}, @dots{} @var{module}

Delete each listed @var{module} from the current archive; equivalent to

@samp{ar -d @var{archive} @var{module} @dots{} @var{module}}.

Requires prior use of @code{OPEN} or @code{CREATE}.

@item DIRECTORY @var{archive} (@var{module}, @dots{} @var{module})

@itemx DIRECTORY @var{archive} (@var{module}, @dots{} @var{module}) @var{outputfile}

List each named @var{module} present in @var{archive}. The separate

command @code{VERBOSE} specifies the form of the output: when verbose

output is off, output is like that of @samp{ar -t @var{archive}

@var{module}@dots{}}. When verbose output is on, the listing is like

@samp{ar -tv @var{archive} @var{module}@dots{}}.

Output normally goes to the standard output stream; however, if you

specify @var{outputfile} as a final argument, @command{ar} directs the

output to that file.

@item END

Exit from @command{ar}, with a @code{0} exit code to indicate successful

completion. This command does not save the output file; if you have

changed the current archive since the last @code{SAVE} command, those

changes are lost.

@item EXTRACT @var{module}, @var{module}, @dots{} @var{module}

Extract each named @var{module} from the current archive, writing them

into the current directory as separate files. Equivalent to @samp{ar -x

@var{archive} @var{module}@dots{}}.

Requires prior use of @code{OPEN} or @code{CREATE}.

@ignore

@c FIXME Tokens but no commands???

@item FULLDIR

@item HELP

@end ignore

@item LIST

Display full contents of the current archive, in ``verbose'' style

regardless of the state of @code{VERBOSE}. The effect is like @samp{ar

tv @var{archive}}. (This single command is a @sc{gnu} @command{ar}

enhancement, rather than present for MRI compatibility.)

Requires prior use of @code{OPEN} or @code{CREATE}.

@item OPEN @var{archive}

Opens an existing archive for use as the current archive (required for

many other commands). Any changes as the result of subsequent commands

will not actually affect @var{archive} until you next use @code{SAVE}.

@item REPLACE @var{module}, @var{module}, @dots{} @var{module}

In the current archive, replace each existing @var{module} (named in

the @code{REPLACE} arguments) from files in the current working directory.

To execute this command without errors, both the file, and the module in

the current archive, must exist.

Requires prior use of @code{OPEN} or @code{CREATE}.

@item VERBOSE

Toggle an internal flag governing the output from @code{DIRECTORY}.

When the flag is on, @code{DIRECTORY} output matches output from

@samp{ar -tv }@dots{}.

@item SAVE

Commit your changes to the current archive, and actually save it as a

file with the name specified in the last @code{CREATE} or @code{OPEN}

command.

Requires prior use of @code{OPEN} or @code{CREATE}.

@end table

@iftex

@node ld

@chapter ld

@cindex linker

@kindex ld

The @sc{gnu} linker @command{ld} is now described in a separate manual.

@xref{Top,, Overview,, Using LD: the @sc{gnu} linker}.

@end iftex

@node nm

@chapter nm

@cindex symbols

@kindex nm

@c man title nm list symbols from object files

@smallexample

@c man begin SYNOPSIS nm

nm [@option{-A}|@option{-o}|@option{--print-file-name}] [@option{-a}|@option{--debug-syms}]

[@option{-B}|@option{--format=bsd}] [@option{-C}|@option{--demangle}[=@var{style}]]

[@option{-D}|@option{--dynamic}] [@option{-f}@var{format}|@option{--format=}@var{format}]

[@option{-g}|@option{--extern-only}] [@option{-h}|@option{--help}]

[@option{-l}|@option{--line-numbers}] [@option{-n}|@option{-v}|@option{--numeric-sort}]

[@option{-P}|@option{--portability}] [@option{-p}|@option{--no-sort}]

[@option{-r}|@option{--reverse-sort}] [@option{-S}|@option{--print-size}]

[@option{-s}|@option{--print-armap}] [@option{-t} @var{radix}|@option{--radix=}@var{radix}]

[@option{-u}|@option{--undefined-only}] [@option{-V}|@option{--version}]

[@option{-X 32_64}] [@option{--defined-only}] [@option{--no-demangle}]

[@option{--plugin} @var{name}] [@option{--size-sort}] [@option{--special-syms}]

[@option{--synthetic}] [@option{--with-symbol-versions}] [@option{--target=}@var{bfdname}]

[@var{objfile}@dots{}]

@c man end

@end smallexample

@c man begin DESCRIPTION nm

@sc{gnu} @command{nm} lists the symbols from object files @var{objfile}@dots{}.

If no object files are listed as arguments, @command{nm} assumes the file

@file{a.out}.

For each symbol, @command{nm} shows:

@itemize @bullet

@item

The symbol value, in the radix selected by options (see below), or

hexadecimal by default.

@item

The symbol type. At least the following types are used; others are, as

well, depending on the object file format. If lowercase, the symbol is

usually local; if uppercase, the symbol is global (external). There

are however a few lowercase symbols that are shown for special global

symbols (@code{u}, @code{v} and @code{w}).

@c Some more detail on exactly what these symbol types are used for

@c would be nice.

@table @code

@item A

The symbol's value is absolute, and will not be changed by further

linking.

@item B

@itemx b

The symbol is in the uninitialized data section (known as BSS).

@item C

The symbol is common. Common symbols are uninitialized data. When

linking, multiple common symbols may appear with the same name. If the

symbol is defined anywhere, the common symbols are treated as undefined

references.

@ifclear man

For more details on common symbols, see the discussion of

--warn-common in @ref{Options,,Linker options,ld.info,The GNU linker}.

@end ifclear

@item D

@itemx d

The symbol is in the initialized data section.

@item G

@itemx g

The symbol is in an initialized data section for small objects. Some

object file formats permit more efficient access to small data objects,

such as a global int variable as opposed to a large global array.

@item i

For PE format files this indicates that the symbol is in a section

specific to the implementation of DLLs. For ELF format files this

indicates that the symbol is an indirect function. This is a GNU

extension to the standard set of ELF symbol types. It indicates a

symbol which if referenced by a relocation does not evaluate to its

address, but instead must be invoked at runtime. The runtime

execution will then return the value to be used in the relocation.

@item I

The symbol is an indirect reference to another symbol.

@item N

The symbol is a debugging symbol.

@item p

The symbols is in a stack unwind section.

@item R

@itemx r

The symbol is in a read only data section.

@item S

@itemx s

The symbol is in an uninitialized data section for small objects.

@item T

@itemx t

The symbol is in the text (code) section.

@item U

The symbol is undefined.

@item u

The symbol is a unique global symbol. This is a GNU extension to the

standard set of ELF symbol bindings. For such a symbol the dynamic linker

will make sure that in the entire process there is just one symbol with

this name and type in use.

@item V

@itemx v

The symbol is a weak object. When a weak defined symbol is linked with

a normal defined symbol, the normal defined symbol is used with no error.

When a weak undefined symbol is linked and the symbol is not defined,

the value of the weak symbol becomes zero with no error. On some

systems, uppercase indicates that a default value has been specified.

@item W

@itemx w

The symbol is a weak symbol that has not been specifically tagged as a

weak object symbol. When a weak defined symbol is linked with a normal

defined symbol, the normal defined symbol is used with no error.

When a weak undefined symbol is linked and the symbol is not defined,

the value of the symbol is determined in a system-specific manner without

error. On some systems, uppercase indicates that a default value has been

specified.

@item -

The symbol is a stabs symbol in an a.out object file. In this case, the

next values printed are the stabs other field, the stabs desc field, and

the stab type. Stabs symbols are used to hold debugging information.

@item ?

The symbol type is unknown, or object file format specific.

@end table

@item

The symbol name.

@end itemize

@c man end

@c man begin OPTIONS nm

The long and short forms of options, shown here as alternatives, are

equivalent.

@table @env

@item -A

@itemx -o

@itemx --print-file-name

@cindex input file name

@cindex file name

@cindex source file name

Precede each symbol by the name of the input file (or archive member)

in which it was found, rather than identifying the input file once only,

before all of its symbols.

@item -a

@itemx --debug-syms

@cindex debugging symbols

Display all symbols, even debugger-only symbols; normally these are not

listed.

@item -B

@cindex @command{nm} format

@cindex @command{nm} compatibility

The same as @option{--format=bsd} (for compatibility with the MIPS @command{nm}).

@item -C

@itemx --demangle[=@var{style}]

@cindex demangling in nm

Decode (@dfn{demangle}) low-level symbol names into user-level names.

Besides removing any initial underscore prepended by the system, this

makes C++ function names readable. Different compilers have different

mangling styles. The optional demangling style argument can be used to

choose an appropriate demangling style for your compiler. @xref{c++filt},

for more information on demangling.

@item --no-demangle

Do not demangle low-level symbol names. This is the default.

@item -D

@itemx --dynamic

@cindex dynamic symbols

Display the dynamic symbols rather than the normal symbols. This is

only meaningful for dynamic objects, such as certain types of shared

libraries.

@item -f @var{format}

@itemx --format=@var{format}

@cindex @command{nm} format

@cindex @command{nm} compatibility

Use the output format @var{format}, which can be @code{bsd},

@code{sysv}, or @code{posix}. The default is @code{bsd}.

Only the first character of @var{format} is significant; it can be

either upper or lower case.

@item -g

@itemx --extern-only

@cindex external symbols

Display only external symbols.

@item -h

@itemx --help

Show a summary of the options to @command{nm} and exit.

@item -l

@itemx --line-numbers

@cindex symbol line numbers

For each symbol, use debugging information to try to find a filename and

line number. For a defined symbol, look for the line number of the

address of the symbol. For an undefined symbol, look for the line

number of a relocation entry which refers to the symbol. If line number

information can be found, print it after the other symbol information.

@item -n

@itemx -v

@itemx --numeric-sort

Sort symbols numerically by their addresses, rather than alphabetically

by their names.

@item -p

@itemx --no-sort

@cindex sorting symbols

Do not bother to sort the symbols in any order; print them in the order

encountered.

@item -P

@itemx --portability

Use the POSIX.2 standard output format instead of the default format.

Equivalent to @samp{-f posix}.

@item -r

@itemx --reverse-sort

Reverse the order of the sort (whether numeric or alphabetic); let the

last come first.

@item -S

@itemx --print-size

Print both value and size of defined symbols for the @code{bsd} output style.

This option has no effect for object formats that do not record symbol

sizes, unless @samp{--size-sort} is also used in which case a

calculated size is displayed.

@item -s

@itemx --print-armap

@cindex symbol index, listing

When listing symbols from archive members, include the index: a mapping

(stored in the archive by @command{ar} or @command{ranlib}) of which modules

contain definitions for which names.

@item -t @var{radix}

@itemx --radix=@var{radix}

Use @var{radix} as the radix for printing the symbol values. It must be

@samp{d} for decimal, @samp{o} for octal, or @samp{x} for hexadecimal.

@item -u

@itemx --undefined-only

@cindex external symbols

@cindex undefined symbols

Display only undefined symbols (those external to each object file).

@item -V

@itemx --version

Show the version number of @command{nm} and exit.

@item -X

This option is ignored for compatibility with the AIX version of

@command{nm}. It takes one parameter which must be the string

@option{32_64}. The default mode of AIX @command{nm} corresponds