\input texinfo @c -*- Texinfo -*- @setfilename binutils.info @ifinfo @format START-INFO-DIR-ENTRY * Binutils:: The GNU binary utilities "ar", "ld", "objcopy", "objdump", "nm", "size", "strings", "strip", and "ranlib". END-INFO-DIR-ENTRY @end format @end ifinfo @ifinfo Copyright @copyright{} 1991, 1992, 1993 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 @c @smallbook @c @cropmarks @titlepage @finalout @title The GNU Binary Utilities @subtitle Version 2.2 @sp 1 @subtitle May 1993 @author Roland H. Pesch @author Cygnus Support @page @tex \def\$#1${{#1}} % Kluge: collect RCS revision info without $...$ \xdef\manvers{\$Revision$} % For use in headers, footers too {\parskip=0pt \hfill Cygnus Support\par \hfill \manvers\par \hfill \TeX{}info \texinfoversion\par } @end tex @vskip 0pt plus 1filll Copyright @copyright{} 1991, 1992, 1993 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, ar, (dir), (dir) @chapter 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 objcopy Copy and translate object files @item nm List symbols from object files @item objdump Display information from object files @item ranlib Generate index to archive contents @item size List section sizes and total size @item strings List printable strings from files @item strip Discard symbols @end table @end iftex @menu * ar:: Create, modify, and extract from archives * objcopy:: Copy and translate object files * ld:(ld)Overview. Combine object and archive files * nm:: List symbols from 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 * Index:: @end menu @node ar, objcopy, Top, Top @chapter ar @kindex ar @cindex archives @cindex collections of files @smallexample ar [-]@var{p}@var{mod} [ @var{membername} ] @var{archive} @var{file}@dots{} ar -M [ }), 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{file}, @var{file}, @dots{} @var{file} @c FIXME! w/Replacement?? If so, like "ar r @var{archive} @var{names}" @c else like "ar q..." Add each named @var{file} 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 @node objcopy, nm, ar, Top @chapter objcopy @smallexample objcopy [ -F @var{format} | --format=@var{format} ] [ -I @var{format} | --input-format=@var{format} ] [ -O @var{format} | --output-format=@var{format} ] [ -S | --strip-all ] [ -g | --strip-debug ] [ -x | --discard-all ] [ -X | --discard-locals ] [ -v | --verbose ] [ -V | --version ] [ --help ] @var{infile} [@var{outfile}] @end smallexample The GNU @code{objcopy} utility copies the contents of an object file to another. @code{objcopy} uses the GNU 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 BFD to do all its translation work; it knows about all the formats BFD knows about, and thus is able to recognize most formats without being told explicitly. @xref{BFD,,BFD,ld.info,Using LD, the GNU linker}. @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 the input file. @item -I @var{format} @itemx --input-format=@var{format} Consider the source file's object format to be @var{format}, rather than attempting to deduce it. @item -O @var{format} @itemx --output-format=@var{format} Write the output file using the object format @var{format}. @item -F @var{format} @itemx --format=@var{format} Use @var{format} as the object format for both the input and the output file; i.e. simply transfer data from source to destination with no translation. @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 -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 @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, objdump, objcopy, Top @chapter nm @cindex symbols @kindex nm @smallexample nm [ -a | --debug-syms ] [ -g | --extern-only ] [ -B ] [ -C | --demangle ] [ -s | --print-armap ] [ -A | -o | --print-file-name ] [ -n | -v | --numeric-sort ] [ -p | --no-sort ] [ -r | --reverse-sort ] [ -u | --undefined-only ] [ -t @var{radix} | --radix=@var{radix} ] [ -P | --portability ] [ --target=@var{bfdname} ] [ -f @var{format} | --format=@var{format} ] [ -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 -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 Don't 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 -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{objdump}, for information on listing available formats. @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 objdump, ranlib, nm, Top @chapter objdump @cindex object file information @kindex objdump @smallexample objdump [ -a ] [ -b @var{bfdname} ] [ -d ] [ -f ] [ -h | --header ] [ -i ] [ -j @var{section} ] [ -l ] [ -m @var{machine} ] [ -r | --reloc ] [ -s ] [ --stabs ] [ -t | --syms ] [ -x ] [ --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 @c print_arelt_descr @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. @c suggest longname --target or --format or --bfd @item -b @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. @item -d @cindex disassembling object code @cindex machine instructions Disassemble. Display the assembler mnemonics for the machine instructions from @var{objfile}. @item -f @cindex object file header File header. Display summary information from the overall header of each of the @var{objfile} files. @item -h @itemx --header @cindex section headers Header. Display summary information from the section headers of the object file. @item --help Print a summary of the options to @code{objdump} and exit. @item -i @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}. @c suggest longname --section @item -j @var{name} @cindex section information Display information only for section @var{name}. @c suggest longname --label or --linespec @item -l @cindex source filenames for object files Label the display (using debugging information) with the source filename and line numbers corresponding to the object code shown. @c suggest longname --architecture @item -m @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 Relocation. Print the relocation entries of the file. @item -s @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 Symbol Table. Print the symbol table entries of the file. This is similar to the information provided by the @samp{nm} program. @item --version Print the version number of @code{objdump} and exit. @item -x @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, size, objdump, Top @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, strings, ranlib, Top @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{objdump}, for information on listing available formats. @item -V @itemx --version Display the version number of @code{size}. @end table @node strings, strip, size, Top @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}] [--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 -v @itemx --version Print the program version number on the standard output and exit. @end table @node strip, c++filt, strings, Top @chapter strip @kindex strip @cindex removing symbols @cindex discarding symbols @cindex symbols, discarding @smallexample strip [ -F @var{format} | --format=@var{format} | --target=@var{format} ] [ -I @var{format} | --input-format=@var{format} ] [ -O @var{format} | --output-format=@var{format} ] [ -s | --strip-all ] [ -S | -g | --strip-debug ] [ -x | --discard-all ] [ -X | --discard-locals ] [ -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{format} @itemx --format=@var{format} @itemx --target=@var{format} Treat the original @var{objfile} as a file with the object code format @var{format}, and rewrite it in the same format. @item --help Show a summary of the options to @code{strip} and exit. @item -I @var{format} @itemx --input-format=@var{format} Treat the original @var{objfile} as a file with the object code format @var{format}. @item -O @var{format} @itemx --output-format=@var{format} Replace @var{objfile} with a file in the output format @var{format}. @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, Index, strip, Top @chapter c++filt @kindex c++filt @cindex demangling C++ symbols @smallexample c++filt [ -_ | --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 -_ @item --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. @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 Index, , c++filt, Top @unnumbered Index @printindex cp @contents @bye