* objcopy.c (gap_fill): Explicitly initialize, for clarity.

[deliverable/binutils-gdb.git] / binutils / binutils.texi

\input texinfo       @c                    -*- Texinfo -*-
@setfilename binutils.info

@ifinfo
@format
START-INFO-DIR-ENTRY
* Binutils: (binutils).         The GNU binary utilities "ar", "objcopy",
                                "objdump", "nm", "nlmconv", "size", 
                                "strings", "strip", and "ranlib".
END-INFO-DIR-ENTRY
@end format
@end ifinfo

@ifinfo
Copyright @copyright{} 1991, 1992, 1993, 1994 Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

@ignore
Permission is granted to process this file through TeX and print the
results, provided the printed document carries a copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).

@end ignore

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided also that
the entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions.
@end ifinfo

@synindex ky cp
@c
@c This file documents the GNU binary utilities "ar", "ld", "objcopy",
@c  "objdump", "nm", "size", "strings", "strip", and "ranlib".
@c
@c Copyright (C) 1991, 1992, 1993 Free Software Foundation, Inc.
@c 
@c This text may be freely distributed under the terms of the GNU
@c General Public License.
@c

@setchapternewpage odd
@settitle GNU Binary Utilities
@titlepage
@finalout
@title The GNU Binary Utilities
@subtitle Version 2.2
@sp 1
@subtitle May 1993
@author Roland H. Pesch
@author Jeffrey M. Osier
@author Cygnus Support
@page

@tex
{\parskip=0pt \hfill Cygnus Support\par \hfill
\TeX{}info \texinfoversion\par }
@end tex

@vskip 0pt plus 1filll
Copyright @copyright{} 1991, 1992, 1993, 1994 Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided also that
the entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions.
@end titlepage

@node Top
@top Introduction

@cindex version
This brief manual contains preliminary documentation for the GNU binary
utilities (collectively version 2.2): 

@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 size
List file section sizes and total size

@item strings
List printable strings from files

@item strip
Discard symbols

@item c++filt
Demangle encoded C++ symbols

@item nlmconv
Convert object code into a Netware Loadable Module
@end table
@end iftex

@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
* nlmconv::                     Converts object code into an NLM
* Selecting The Target System:: How these utilities determine the target.
* Index::                       
@end menu

@node ar
@chapter ar

@kindex ar
@cindex archives
@cindex collections of files
@smallexample
ar [-]@var{p}[@var{mod} [@var{relpos}]] @var{archive} [@var{member}@dots{}]
ar -M [ <mri-script ]
@end smallexample

The GNU @code{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
GNU @code{ar} can maintain archives whose members have names of any
length; however, depending on how @code{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
@code{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
@code{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 @code{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 @code{ar} called
@code{ranlib} can be used to add just the table.

@cindex compatibility, @code{ar}
@cindex @code{ar} compatibility
GNU @code{ar} is designed to be compatible with two different
facilities.  You can control its activity using command-line options,
like the different varieties of @code{ar} on Unix systems; or, if you
specify the single command-line option @samp{-M}, you can control it
with a script supplied via standard input, like the MRI ``librarian''
program.

@menu
* ar cmdline::                  Controlling @code{ar} on the command line
* ar scripts::                  Controlling @code{ar} with a script
@end menu

@page
@node ar cmdline
@section Controlling @code{ar} on the command line

@smallexample
ar [-]@var{p}[@var{mod} [@var{relpos}]] @var{archive} [@var{member}@dots{}]
@end smallexample

@cindex Unix compatibility, @code{ar}
When you use @code{ar} in the Unix style, @code{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.

GNU @code{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 @code
@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, @code{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}; 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 @code{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 @samp{ar s} or
@code{ranlib} explicitly to update the symbol table index.

@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, @code{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 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
@code{ar} list each name as it extracts it.

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

@end table

A number of modifiers (@var{mod}) may immediately follow the @var{p}
keyletter, to specify variations on an operation's behavior:

@table @code
@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 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???---pesch@@cygnus.com, 25jan91 

@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 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 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 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 @code{ar}.
@end table

@node ar scripts
@section Controlling @code{ar} with a script

@smallexample
ar -M [ <@var{script} ]
@end smallexample

@cindex MRI compatibility, @code{ar}
@cindex scripts, @code{ar}
If you use the single command-line option @samp{-M} with @code{ar}, you
can control its operation with a rudimentary command language.  This
form of @code{ar} operates interactively if standard input is coming
directly from a terminal.  During interactive use, @code{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 @code{ar} abandons execution (with a nonzero exit code)
on any error.

The @code{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 GNU @code{ar} for developers who already have scripts
written for the MRI ``librarian'' program.

The syntax for the @code{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 @code{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 @code{ar} scripts, or when using
@code{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, cancelling 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, @code{ar} directs the
output to that file.

@item END
Exit from @code{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 GNU @code{ld}
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 GNU linker @code{ld} is now described in a separate manual.
@xref{Top,, Overview,, Using LD: the GNU linker}.
@end iftex

@node nm
@chapter nm
@cindex symbols
@kindex nm

@smallexample
nm [ -a | --debug-syms ]  [ -g | --extern-only ]
   [ -B ]  [ -C | --demangle ] [ -D | --dynamic ]
   [ -s | --print-armap ]  [ -A | -o | --print-file-name ]
   [ -n | -v | --numeric-sort ]  [ -p | --no-sort ]
   [ -r | --reverse-sort ]  [ --size-sort ] [ -u | --undefined-only ]
   [ -t @var{radix} | --radix=@var{radix} ] [ -P | --portability ]
   [ --target=@var{bfdname} ] [ -f @var{format} | --format=@var{format} ]
   [ --no-demangle ] [ -V | --version ]  [ --help ]  [ @var{objfile}@dots{} ]
@end smallexample

GNU @code{nm} lists the symbols from object files @var{objfile}@dots{}.
If no object files are listed as arguments, @code{nm} assumes
@file{a.out}.

For each symbol, @code{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
local; if uppercase, the symbol is global (external).

@c Some more detail on exactly what these symbol types are used for
@c would be nice.
@table @code
@item A
Absolute.

@item B
BSS (uninitialized data).

@item C
Common.

@item D
Initialized data.

@item I
Indirect reference.

@item T
Text (program code).

@item U
Undefined.
@end table

@item
The symbol name.
@end itemize

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

@table @code
@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 element)
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 @code{nm} format
@cindex @code{nm} compatibility
The same as @samp{--format=bsd} (for compatibility with the MIPS @code{nm}).

@item -C
@itemx --demangle
@cindex demangling C++ symbols
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.  @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 @code{nm} format
@cindex @code{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 -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 -s
@itemx --print-armap
@cindex symbol index, listing
When listing symbols from archive members, include the index: a mapping
(stored in the archive by @code{ar} or @code{ranlib}) of which modules
contain definitions for which names.

@item -r
@itemx --reverse-sort 
Reverse the order of the sort (whether numeric or alphabetic); let the
last come first.

@item --size-sort
Sort symbols by size.  The size is computed as the difference between
the value of the symbol and the value of the symbol with the next higher
value.  The size of the symbol is printed, rather than the value.

@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 --target=@var{bfdname}
@cindex object code format
Specify an object code format other than your system's default format.
@xref{Target Selection}, for more information.

@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 @code{nm} and exit.

@item --help
Show a summary of the options to @code{nm} and exit.
@end table

@node objcopy
@chapter objcopy

@smallexample
objcopy [ -F @var{bfdname} | --target=@var{bfdname} ]
        [ -I @var{bfdname} | --input-target=@var{bfdname} ]
        [ -O @var{bfdname} | --output-target=@var{bfdname} ]
        [ -S | --strip-all ]  [ -g | --strip-debug ]
        [ -x | --discard-all ]  [ -X | --discard-locals ]
        [ -b @var{byte} | --byte=@var{byte} ]
        [ -i @var{interleave} | --interleave=@var{interleave} ]
        [ -R @var{sectionname} | --remove-section=@var{sectionname} ]
        [ --gap-fill=@var{val} ] [ --pad-to=@var{address} ]
        [ --set-start=@var{val} ] [ --adjust-start=@var{incr} ]
        [ --adjust-vma=@var{incr} ]
        [ --adjust-section-vma=@var{section}@{=,+,-@}@var{val} ]
        [ --adjust-warnings ] [ --no-adjust-warnings ]
        [ -v | --verbose ] [ -V | --version ]  [ --help ]
        @var{infile} [@var{outfile}]
@end smallexample

The @sc{gnu} @code{objcopy} utility copies the contents of an object
file to another.  @code{objcopy} uses the @sc{gnu} @sc{bfd} Library to
read and write the object files.  It can write the destination object
file in a format different from that of the source object file.  The
exact behavior of @code{objcopy} is controlled by command-line options.

@code{objcopy} creates temporary files to do its translations and
deletes them afterward.  @code{objcopy} uses @sc{bfd} to do all its
translation work; it has access to all the formats described in @sc{bfd}
and thus is able to recognize most formats without being told
explicitly.  @xref{BFD,,BFD,ld.info,Using LD}.

@code{objcopy} can be used to generate S-records by using an output
target of @samp{srec} (e.g., use @samp{-O srec}).

@code{objcopy} can be used to generate a raw binary file by using an
output target of @samp{binary} (e.g., use @samp{-O binary}).  When
@code{objcopy} generates a raw binary file, it will essentially produce
a memory dump of the contents of the input object file.  All symbols and
relocation information will be discarded.  The memory dump will start at
the virtual address of the lowest section copied into the output file.

When generating an S-record or a raw binary file, it may be helpful to
use @samp{-S} to remove sections containing debugging information.  In
some cases @samp{-R} will be useful to remove sections which contain
information which is not needed by the binary file.

@table @code
@item @var{infile}
@itemx @var{outfile}
The source and output files, respectively.
If you do not specify @var{outfile}, @code{objcopy} creates a
temporary file and destructively renames the result with
the name of @var{infile}.

@item -I @var{bfdname}  
@itemx --input-target=@var{bfdname}
Consider the source file's object format to be @var{bfdname}, rather than
attempting to deduce it.  @xref{Target Selection}, for more information.

@item -O @var{bfdname}
@itemx --output-target=@var{bfdname}
Write the output file using the object format @var{bfdname}.
@xref{Target Selection}, for more information.

@item -F @var{bfdname}
@itemx --target=@var{bfdname}
Use @var{bfdname} as the object format for both the input and the output
file; i.e., simply transfer data from source to destination with no
translation.  @xref{Target Selection}, for more information.

@item -R @var{sectionname}
@itemx --remove-section=@var{sectionname}
Remove any section named @var{sectionname} from the output file.  This
option may be given more than once.  Note that using this option
inappropriately may make the output file unusable.

@item -S
@itemx --strip-all
Do not copy relocation and symbol information from the source file.

@item -g
@itemx --strip-debug
Do not copy debugging symbols from the source file.

@item -x
@itemx --discard-all
Do not copy non-global symbols from the source file.
@c FIXME any reason to prefer "non-global" to "local" here?

@item -X
@itemx --discard-locals
Do not copy compiler-generated local symbols.
(These usually start with @samp{L} or @samp{.}.)

@item -b @var{byte}
@itemx --byte=@var{byte}
Keep only every @var{byte}th byte of the input file (header data is not
affected).  @var{byte} can be in the range from 0 to @var{interleave}-1,
where @var{interleave} is given by the @samp{-i} or @samp{--interleave}
option, or the default of 4.  This option is useful for creating files
to program @sc{rom}.  It is typically used with an @code{srec} output
target.

@item -i @var{interleave}
@itemx --interleave=@var{interleave}
Only copy one out of every @var{interleave} bytes.  Select which byte to
copy with the @var{-b} or @samp{--byte} option.  The default is 4.
@code{objcopy} ignores this option if you do not specify either @samp{-b} or
@samp{--byte}.

@item --gap-fill @var{val}
Fill gaps between sections with @var{val}.  This is done by increasing
the size of the section with the lower address, and filling in the extra
space created with @var{val}.

@item --pad-to @var{address}
Pad the output file up to the virtual address @var{address}.  This is
done by increasing the size of the last section.  The extra space is
filled in with the value specified by @samp{--gap-fill} (default zero).

@item --set-start @var{val}
Set the address of the new file to @var{val}.  Not all object file
formats support setting the start address.

@item --adjust-start @var{incr}
Adjust the start address by adding @var{incr}.  Not all object file
formats support setting the start address.

@item --adjust-vma @var{incr}
Adjust the address of all sections, as well as the start address, by
adding @var{incr}.  Some object file formats do not permit section
addresses to be changed arbitrarily.  Note that this does not relocate
the sections; if the program expects sections to be loaded at a certain
address, and this option is used to change the sections such that they
are loaded at a different address, the program may fail.

@item --adjust-section-vma @var{section}@{=,+,-@}@var{val}
Set or adjust the address of the named @var{section}.  If @samp{=} is
used, the section address is set to @var{val}.  Otherwise, @var{val} is
added to or subtracted from the section address.  See the comments under
@samp{--adjust-vma}, above.  If @var{section} does not exist in the
input file, a warning will be issued, unless @samp{--no-adjust-warnings}
is used.

@item --adjust-warnings
If @samp{--adjust-section-vma} is used, and the named section does not
exist, issue a warning.  This is the default.

@item --no-adjust-warnings
Do not issue a warning if @samp{--adjust-section-vma} is used, even if
the named section does not exist.

@item -V
@itemx --version
Show the version number of @code{objcopy}.

@item -v
@itemx --verbose
Verbose output: list all object files modified.  In the case of
archives, @samp{objcopy -V} lists all members of the archive.

@item --help
Show a summary of the options to @code{objcopy}.
@end table

@node objdump
@chapter objdump

@cindex object file information
@kindex objdump

@smallexample
objdump [ -a | --archive-headers ] 
        [ -b @var{bfdname} | --target=@var{bfdname} ]
        [ -d | --disassemble ]  [ -D | --disassemble-all ] 
        [ -f | --file-headers ]
        [ -h | --section-headers | --headers ]  [ -i | --info ]
        [ -j @var{section} | --section=@var{section} ]
        [ -l | --line-numbers ]
        [ -m @var{machine} | --architecture=@var{machine} ]
        [ -r | --reloc ] [ -R | --dynamic-reloc ]
        [ -s | --full-contents ]  [ --stabs ]
        [ -t | --syms ] [ -T | --dynamic-syms ] [ -x | --all-headers ]
        [ --version ]  [ --help ] @var{objfile}@dots{}
@end smallexample

@code{objdump} displays information about one or more object files.
The options control what particular information to display.  This
information is mostly useful to programmers who are working on the
compilation tools, as opposed to programmers who just want their
program to compile and work.

@var{objfile}@dots{} are the object files to be examined.  When you
specify archives, @code{objdump} shows information on each of the member
object files.

The long and short forms of options, shown here as alternatives, are
equivalent.  At least one option besides @samp{-l} must be given.

@table @code
@item -a
@itemx --archive-header
@cindex archive headers
If any of the @var{objfile} files are archives, display the archive
header information (in a format similar to @samp{ls -l}).  Besides the
information you could list with @samp{ar tv}, @samp{objdump -a} shows
the object file format of each archive member.

@item -b @var{bfdname}
@itemx --target=@var{bfdname}
@cindex object code format
Specify that the object-code format for the object files is
@var{bfdname}.  This option may not be necessary; @var{objdump} can
automatically recognize many formats.

For example,
@example
objdump -b oasys -m vax -h fu.o
@end example
@noindent
displays summary information from the section headers (@samp{-h}) of
@file{fu.o}, which is explicitly identified (@samp{-m}) as a VAX object
file in the format produced by Oasys compilers.  You can list the
formats available with the @samp{-i} option.
@xref{Target Selection}, for more information.

@item -d
@itemx --disassemble
@cindex disassembling object code
@cindex machine instructions
Display the assembler mnemonics for the machine instructions from
@var{objfile}.  This option only disassembles those sections which are
expected to contain instructions.

@item -D
@itemx --disassemble-all
Like @samp{-d}, but disassemble the contents of all sections, not just
those expected to contain instructions.

@item -f
@itemx --file-header
@cindex object file header
Display summary information from the overall header of
each of the @var{objfile} files.

@item -h
@itemx --section-header
@itemx --header
@cindex section headers
Display summary information from the section headers of the
object file.

File segments may be relocated to nonstandard addresses, for example by
using the @samp{-Ttext}, @samp{-Tdata}, or @samp{-Tbss} options to
@code{ld}.  However, some object file formats, such as a.out, do not
store the starting address of the file segments.  In those situations,
although @code{ld} relocates the sections correctly, using @samp{objdump
-h} to list the file section headers cannot show the correct addresses.
Instead, it shows the usual addresses, which are implicit for the
target.

@item --help
Print a summary of the options to @code{objdump} and exit.

@item -i
@itemx --info
@cindex architectures available
@cindex object formats available
Display a list showing all architectures and object formats available
for specification with @samp{-b} or @samp{-m}.

@item -j @var{name}
@itemx --section=@var{name}
@cindex section information
Display information only for section @var{name}.

@item -l
@itemx --line-numbers
@cindex source filenames for object files
Label the display (using debugging information) with the filename
and source line numbers corresponding to the object code shown.
Only useful with @samp{-d} or @samp{-D}.

@item -m @var{machine}
@itemx --architecture=@var{machine}
@cindex architecture
Specify that the object files @var{objfile} are for architecture
@var{machine}.  You can list available architectures using the @samp{-i}
option. 

@item -r
@itemx --reloc
@cindex relocation entries, in object file
Print the relocation entries of the file.  If used with @samp{-d} or
@samp{-D}, the relocations are printed interspersed with the
disassembly.

@item -R
@itemx --dynamic-reloc
@cindex dynamic relocation entries, in object file
Print the dynamic relocation entries of the file.  This is only
meaningful for dynamic objects, such as certain types of shared
libraries.

@item -s
@itemx --full-contents
@cindex sections, full contents
@cindex object file sections
Display the full contents of any sections requested.

@item --stabs
@cindex stab
@cindex .stab
@cindex debug symbols
@cindex ELF object file format
Display the full contents of any sections requested.  Display the
contents of the .stab and .stab.index and .stab.excl sections from an
ELF file.  This is only useful on systems (such as Solaris 2.0) in which
@code{.stab} debugging symbol-table entries are carried in an ELF
section.  In most other file formats, debugging symbol-table entries are
interleaved with linkage symbols, and are visible in the @samp{--syms}
output.

@item -t
@itemx --syms
@cindex symbol table entries, printing
Print the symbol table entries of the file.
This is similar to the information provided by the @samp{nm} program.

@item -T
@itemx --dynamic-syms
@cindex dynamic symbol table entries, printing
Print the dynamic symbol table entries of the file.  This is only
meaningful for dynamic objects, such as certain types of shared
libraries.  This is similar to the information provided by the @samp{nm}
program when given the @samp{-D} (@samp{--dynamic}) option.

@item --version
Print the version number of @code{objdump} and exit.

@item -x
@itemx --all-header
@cindex all header information, object file
@cindex header information, all
Display all available header information, including the symbol table and
relocation entries.  Using @samp{-x} is equivalent to specifying all of
@samp{-a -f -h -r -t}.
@end table

@node ranlib
@chapter ranlib

@kindex ranlib
@cindex archive contents
@cindex symbol index

@smallexample
ranlib [-vV] @var{archive}
@end smallexample

@code{ranlib} generates an index to the contents of an archive and
stores it in the archive.  The index lists each symbol defined by a
member of an archive that is a relocatable object file.  

You may use @samp{nm -s} or @samp{nm --print-armap} to list this index.

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.

The GNU @code{ranlib} program is another form of GNU @code{ar}; running
@code{ranlib} is completely equivalent to executing @samp{ar -s}.
@xref{ar}.

@table @code
@item -v
@itemx -V
Show the version number of @code{ranlib}.
@end table

@node size
@chapter size

@kindex size
@cindex section sizes

@smallexample
size [ -A | -B | --format=@var{compatibility} ]
     [ --help ]  [ -d | -o | -x | --radix=@var{number} ]
     [ --target=@var{bfdname} ]  [ -V | --version ]  
     @var{objfile}@dots{}
@end smallexample

The GNU @code{size} utility lists the section sizes---and the total
size---for each of the object or archive files @var{objfile} in its
argument list.  By default, one line of output is generated for each
object file or each module in an archive.

@var{objfile}@dots{} are the object files to be examined.

The command line options have the following meanings:

@table @code
@item -A
@itemx -B
@itemx --format=@var{compatibility}
@cindex @code{size} display format
Using one of these options, you can choose whether the output from GNU
@code{size} resembles output from System V @code{size} (using @samp{-A},
or @samp{--format=sysv}), or Berkeley @code{size} (using @samp{-B}, or
@samp{--format=berkeley}).  The default is the one-line format similar to
Berkeley's.  
@c Bonus for doc-source readers: you can also say --format=strange (or
@c anything else that starts with 's') for sysv, and --format=boring (or
@c anything else that starts with 'b') for Berkeley.

Here is an example of the Berkeley (default) format of output from
@code{size}: 
@smallexample
size --format=Berkeley ranlib size
text    data    bss     dec     hex     filename
294880  81920   11592   388392  5ed28   ranlib
294880  81920   11888   388688  5ee50   size
@end smallexample

@noindent
This is the same data, but displayed closer to System V conventions:

@smallexample
size --format=SysV ranlib size
ranlib  :
section         size         addr
.text         294880         8192       
.data          81920       303104       
.bss           11592       385024       
Total         388392    


size  :
section         size         addr
.text         294880         8192       
.data          81920       303104       
.bss           11888       385024       
Total         388688    
@end smallexample

@item --help
Show a summary of acceptable arguments and options.

@item -d
@itemx -o
@itemx -x
@itemx --radix=@var{number}
@cindex @code{size} number format
@cindex radix for section sizes
Using one of these options, you can control whether the size of each
section is given in decimal (@samp{-d}, or @samp{--radix=10}); octal
(@samp{-o}, or @samp{--radix=8}); or hexadecimal (@samp{-x}, or
@samp{--radix=16}).  In @samp{--radix=@var{number}}, only the three
values (8, 10, 16) are supported.  The total size is always given in two
radices; decimal and hexadecimal for @samp{-d} or @samp{-x} output, or
octal and hexadecimal if you're using @samp{-o}.

@item --target=@var{bfdname}
@cindex object code format
Specify that the object-code format for @var{objfile} is
@var{bfdname}.  This option may not be necessary; @code{size} can
automatically recognize many formats.
@xref{Target Selection}, for more information.

@item -V
@itemx --version
Display the version number of @code{size}.
@end table

@node strings
@chapter strings
@kindex strings
@cindex listings strings
@cindex printing strings
@cindex strings, printing

@smallexample
strings [-afov] [-@var{min-len}] [-n @var{min-len}] [-t @var{radix}] [-]
        [--all] [--print-file-name] [--bytes=@var{min-len}]
        [--radix=@var{radix}] [--target=@var{bfdname}]
        [--help] [--version] @var{file}@dots{}
@end smallexample

For each @var{file} given, GNU @code{strings} prints the printable
character sequences that are at least 4 characters long (or the number
given with the options below) and are followed by a NUL or newline
character.  By default, it only prints the strings from the initialized
data sections of object files; for other types of files, it prints the
strings from the whole file.

@code{strings} is mainly useful for determining the contents of non-text
files.

@table @code
@item -a
@itemx --all
@itemx -
Do not scan only the initialized data section of object files; scan
the whole files.

@item -f
@itemx --print-file-name
Print the name of the file before each string.

@item --help
Print a summary of the program usage on the standard output and exit.

@itemx -@var{min-len}
@item -n @var{min-len}
@itemx --bytes=@var{min-len}
Print sequences of characters that are at least @var{min-len} characters
long, instead of the default 4.

@item -o
Like @samp{-t o}.  Some other versions of @code{strings} have @samp{-o}
act like @samp{-t d} instead.  Since we can not be compatible with both
ways, we simply chose one.

@item -t @var{radix}
@itemx --radix=@var{radix}
Print the offset within the file before each string.  The single
character argument specifies the radix of the offset---@samp{o} for
octal, @samp{x} for hexadecimal, or @samp{d} for decimal.

@item --target=@var{bfdname}
@cindex object code format
Specify an object code format other than your system's default format.
@xref{Target Selection}, for more information.

@item -v
@itemx --version
Print the program version number on the standard output and exit.
@end table

@node strip
@chapter strip

@kindex strip
@cindex removing symbols
@cindex discarding symbols
@cindex symbols, discarding

@smallexample
strip [ -F @var{bfdname} | --target=@var{bfdname} | --target=@var{bfdname} ]
      [ -I @var{bfdname} | --input-target=@var{bfdname} ]
      [ -O @var{bfdname} | --output-target=@var{bfdname} ]
      [ -s | --strip-all ] [ -S | -g | --strip-debug ]
      [ -x | --discard-all ] [ -X | --discard-locals ]
      [ -R @var{sectionname} | --remove-section=@var{sectionname} ]
      [ -v | --verbose ]  [ -V | --version ]  [ --help ]
      @var{objfile}@dots{}
@end smallexample

GNU @code{strip} discards all symbols from object files
@var{objfile}.  The list of object files may include archives.
At least one object file must be given.

@code{strip} modifies the files named in its argument,
rather than writing modified copies under different names.

@table @code
@item -F @var{bfdname}
@itemx --target=@var{bfdname}
Treat the original @var{objfile} as a file with the object
code format @var{bfdname}, and rewrite it in the same format.
@xref{Target Selection}, for more information.

@item --help
Show a summary of the options to @code{strip} and exit.

@item -I @var{bfdname}  
@itemx --input-target=@var{bfdname}
Treat the original @var{objfile} as a file with the object
code format @var{bfdname}.
@xref{Target Selection}, for more information.

@item -O @var{bfdname}
@itemx --output-target=@var{bfdname}
Replace @var{objfile} with a file in the output format @var{bfdname}.
@xref{Target Selection}, for more information.

@item -R @var{sectionname}
@itemx --remove-section=@var{sectionname}
Remove any section named @var{sectionname} from the output file.  This
option may be given more than once.  Note that using this option
inappropriately may make the output file unusable.

@item -s
@itemx --strip-all
Remove all symbols.

@item -g
@itemx -S
@itemx --strip-debug
Remove debugging symbols only.

@item -x
@itemx --discard-all
Remove non-global symbols.

@item -X
@itemx --discard-locals
Remove compiler-generated local symbols.
(These usually start with @samp{L} or @samp{.}.)

@item -V
@itemx --version
Show the version number for @code{strip}.

@item -v
@itemx --verbose
Verbose output: list all object files modified.  In the case of
archives, @samp{strip -v} lists all members of the archive.
@end table

@node c++filt
@chapter c++filt

@kindex c++filt
@cindex demangling C++ symbols

@smallexample
c++filt [ -_ | --strip-underscores ]
        [ -n | --no-strip-underscores ]
        [ -s @var{format} | --format=@var{format} ]
        [ --help ]  [ --version ]  [ @var{symbol}@dots{} ]
@end smallexample

The C++ language provides function overloading, which means that you can
write many functions with the same name (providing each takes parameters
of different types).  All C++ function names are encoded into a
low-level assembly label (this process is known as
@dfn{mangling}). The @code{c++filt} program does the inverse mapping: it
decodes (@dfn{demangles}) low-level names into user-level names so that
the linker can keep these overloaded functions from clashing.

Every alphanumeric word (consisting of letters, digits, underscores,
dollars, or periods) seen in the input is a potential label.  If the
label decodes into a C++ name, the C++ name replaces the low-level
name in the output.

You can use @code{c++filt} to decipher individual symbols:

@example
c++filt @var{symbol}
@end example

If no @var{symbol} arguments are given, @code{c++filt} reads symbol
names from the standard input and writes the demangled names to the
standard output.  All results are printed on the standard output.

@table @code
@item -_
@itemx --strip-underscores
On some systems, both the C and C++ compilers put an underscore in front
of every name.  For example, the C name @code{foo} gets the low-level
name @code{_foo}.  This option removes the initial underscore.  Whether
@code{c++filt} removes the underscore by default is target dependent.

@item -n
@itemx --no-strip-underscores
Do not remove the initial underscore.

@item -s @var{format}
@itemx --format=@var{format}
GNU @code{nm} can decode three different methods of mangling, used by
different C++ compilers.  The argument to this option selects which
method it uses:

@table @code
@item gnu
the one used by the GNU compiler (the default method)
@item lucid
the one used by the Lucid compiler
@item arm
the one specified by the C++ Annotated Reference Manual
@end table

@item --help
Print a summary of the options to @code{c++filt} and exit.

@item --version
Print the version number of @code{c++filt} and exit.
@end table

@quotation
@emph{Warning:} @code{c++filt} is a new utility, and the details of its
user interface are subject to change in future releases.  In particular,
a command-line option may be required in the the future to decode a name
passed as an argument on the command line; in other words, 

@example
c++filt @var{symbol}
@end example

@noindent
may in a future release become

@example
c++filt @var{option} @var{symbol}
@end example
@end quotation

@node nlmconv
@chapter nlmconv

@code{nlmconv} converts a relocatable object file into a NetWare
Loadable Module.

@ignore
@code{nlmconv} currently works with @samp{i386} object
files in @code{coff}, @sc{elf}, or @code{a.out} format, and @sc{SPARC}
object files in @sc{elf}, or @code{a.out} format@footnote{
@code{nlmconv} should work with any @samp{i386} or @sc{sparc} object
format in the Binary File Descriptor library.  It has only been tested
with the above formats.}.
@end ignore

@quotation
@emph{Warning:} @code{nlmconv} is not always built as part of the binary
utilities, since it is only useful for NLM targets.
@end quotation

@smallexample
nlmconv [ -I @var{bfdname} | --input-target=@var{bfdname} ]
        [ -O @var{bfdname} | --output-target=@var{bfdname} ]
        [ -T @var{headerfile} | --header-file=@var{headerfile} ]
        [ -d | --debug]  [ -l @var{linker} | --linker=@var{linker} ]
        [ -h | --help ]  [ -V | --version ]
        @var{infile} @var{outfile}
@end smallexample

@code{nlmconv} converts the relocatable @samp{i386} object file
@var{infile} into the NetWare Loadable Module @var{outfile}, optionally
reading @var{headerfile} for NLM header information.  For instructions
on writing the NLM command file language used in header files, see the
@samp{linkers} section, @samp{NLMLINK} in particular, of the @cite{NLM
Development and Tools Overview}, which is part of the NLM Software
Developer's Kit (``NLM SDK''), available from Novell, Inc.
@code{nlmconv} uses the @sc{gnu} Binary File Descriptor library to read
@var{infile}; see @ref{BFD,,BFD,ld.info,Using LD}, for
more information.

@code{nlmconv} can perform a link step.  In other words, you can list
more than one object file for input if you list them in the definitions
file (rather than simply specifying one input file on the command line).
In this case, @code{nlmconv} calls the linker for you.

@table @code
@item -I @var{bfdname}
@itemx --input-target=@var{bfdname}
Object format of the input file.  @code{nlmconv} can usually determine
the format of a given file (so no default is necessary).
@xref{Target Selection}, for more information.

@item -O @var{bfdname}
@itemx --output-target=@var{bfdname}
Object format of the output file.  @code{nlmconv} infers the output
format based on the input format, e.g. for a @samp{i386} input file the
output format is @samp{nlm32-i386}.
@xref{Target Selection}, for more information.

@item -T @var{headerfile}
@itemx --header-file=@var{headerfile}
Reads @var{headerfile} for NLM header information.  For instructions on
writing the NLM command file language used in header files, see@ see the
@samp{linkers} section, of the @cite{NLM Development and Tools
Overview}, which is part of the NLM Software Developer's Kit, available
from Novell, Inc.

@item -d
@itemx --debug
Displays (on standard error) the linker command line used by @code{nlmconv}.

@item -l @var{linker}
@itemx --linker=@var{linker}
Use @var{linker} for any linking.  @var{linker} can be an abosolute or a
relative pathname.

@item -h
@itemx --help
Prints a usage summary.

@item -V
@itemx --version
Prints the version number for @code{nlmconv}.
@end table

@node Selecting The Target System
@chapter Selecting the target system

You can specify three aspects of the target system to the @sc{gnu}
binary file utilities, each in several ways:

@itemize @bullet
@item
the target

@item
the architecture

@item
the linker emulation (which applies to the linker only)
@end itemize

In the following summaries, the lists of ways to specify values are in
order of decreasing precedence.  The ways listed first override those
listed later.

The commands to list valid values only list the values for which the
programs you are running were configured.  If they were configured with
@samp{--with-targets=all}, the commands list most of the available
values, but a few are left out; not all targets can be configured in at
once because some of them can only be configured @dfn{native} (on hosts
with the same type as the target system).

@menu
* Target Selection::            
* Architecture Selection::      
* Linker Emulation Selection::  
@end menu

@node Target Selection
@section Target Selection

A @dfn{target} is an object file format.  A given target may be
supported for multiple architectures (@pxref{Architecture Selection}).
A target selection may also have variations for different operating
systems or architectures.

The command to list valid target values is @samp{objdump -i}
(the first column of output contains the relevant information).

Some sample values are: @samp{a.out-hp300bsd}, @samp{ecoff-littlemips},
@samp{a.out-sunos-big}.

@subheading @code{objdump} Target

Ways to specify:

@enumerate
@item
command line option: @samp{-b} or @samp{--target}

@item
environment variable @code{GNUTARGET}

@item
deduced from the input file
@end enumerate

@subheading @code{objcopy} and @code{strip} Input Target

Ways to specify:

@enumerate
@item
command line options: @samp{-I} or @samp{--input-target}, or @samp{-F} or @samp{--target}

@item
environment variable @code{GNUTARGET}

@item
deduced from the input file
@end enumerate

@subheading @code{objcopy} and @code{strip} Output Target

Ways to specify:

@enumerate
@item
command line options: @samp{-O} or @samp{--output-target}, or @samp{-F} or @samp{--target}

@item
the input target (see ``@code{objcopy} and @code{strip} Input Target'' above)

@item
environment variable @code{GNUTARGET}

@item
deduced from the input file
@end enumerate

@subheading @code{nm}, @code{size}, and @code{strings} Target

Ways to specify:

@enumerate
@item
command line option: @samp{--target}

@item
environment variable @code{GNUTARGET}

@item
deduced from the input file
@end enumerate

@subheading Linker Input Target

Ways to specify:

@enumerate
@item
command line option: @samp{-b} or @samp{--format}
(@pxref{Options,,Options,ld.info,Using LD})

@item
script command @code{TARGET}
(@pxref{Option Commands,,Option Commands,ld.info,Using LD})

@item
environment variable @code{GNUTARGET}
(@pxref{Environment,,Environment,ld.info,Using LD})

@item
the default target of the selected linker emulation
(@pxref{Linker Emulation Selection})
@end enumerate

@subheading Linker Output Target

Ways to specify:

@enumerate
@item
command line option: @samp{-oformat}
(@pxref{Options,,Options,ld.info,Using LD})

@item
script command @code{OUTPUT_FORMAT}
(@pxref{Option Commands,,Option Commands,ld.info,Using LD})

@item
the linker input target (see ``Linker Input Target'' above)
@end enumerate

@node Architecture Selection
@section Architecture selection

An @dfn{architecture} is a type of @sc{cpu} on which an object file is
to run.  Its name may contain a colon, separating the name of the
processor family from the name of the particular @sc{cpu}.

The command to list valid architecture values is @samp{objdump -i} (the
second column contains the relevant information).

Sample values: @samp{m68k:68020}, @samp{mips:3000}, @samp{sparc}.

@subheading @code{objdump} Architecture

Ways to specify:

@enumerate
@item
command line option: @samp{-m} or @samp{--architecture}

@item
deduced from the input file
@end enumerate

@subheading @code{objcopy}, @code{nm}, @code{size}, @code{strings} Architecture

Ways to specify:

@enumerate
@item
deduced from the input file
@end enumerate

@subheading Linker Input Architecture

Ways to specify:

@enumerate
@item
deduced from the input file
@end enumerate

@subheading Linker Output Architecture

Ways to specify:

@enumerate
@item
script command @code{OUTPUT_ARCH}
(@pxref{Option Commands,,Option Commands,ld.info,Using LD})

@item
the default architecture from the linker output target
(@pxref{Target Selection})
@end enumerate

@node Linker Emulation Selection
@section Linker emulation selection

A linker @dfn{emulation} is a ``personality'' of the linker, which gives
the linker default values for the other aspects of the target system.
In particular, it consists of

@itemize @bullet
@item
the linker script

@item
the target

@item
several ``hook'' functions that are run at certain stages of the linking
process to do special things that some targets require
@end itemize

The command to list valid linker emulation values is @samp{ld -V}.

Sample values: @samp{hp300bsd}, @samp{mipslit}, @samp{sun4}.

Ways to specify:

@enumerate
@item
command line option: @samp{-m}
(@pxref{Options,,Options,ld.info,Using LD})

@item
environment variable @code{LDEMULATION}

@item
compiled-in @code{DEFAULT_EMULATION} from @file{Makefile},
which comes from @code{EMUL} in @file{config/@var{target}.mt}
@end enumerate

@node Index
@unnumbered Index

@printindex cp

@contents
@bye