最終更新:2019-10-01 (火) 18:16:01 (43d)  

nm はてなブックマークを見る
Top / nm

nm - list symbols from object files

オブジェクトファイルに含まれるシンボル(クラス関数など)を表示する

nm library.a [--demangle]

対象

オプション

  • -A or -oシンボル情報にファイル名を追加
    -l行番号を追加
    -aすべてのシンボルを(デバッグ用も)表示
    -D動的シンボルの情報を表示
    -g外部シンボルのみ表示
    -sアーカイブファイルのインデックスを表示

シンボル種類

  • 小文字はそのシンボルがローカルであることを意味し、大文字はそのシンボルがグローバル (外部定義) であることを意味
    B未初期化データ(bss)グローバル初期化されないデータセクション
    b未初期化データ(bss)ローカル(static)
    D/d初期化されたデータセクション
    Tテキストセクションのシンボルグローバルコードセクション内の普通の定義
    tテキストセクションのシンボルローカル(static)
    U未定義シンボル外部モジュールの公開シンボルを参照している
    Wweak symbolもしも他のライブラリも同じシンボルを定義している場合、その定義によりオーバーライドされる

  • $ nm hello
    0000000000601038 B __bss_start
    0000000000601038 b completed.7594
    0000000000601028 D __data_start
    0000000000601028 W data_start
    0000000000400460 t deregister_tm_clones
    00000000004004e0 t __do_global_dtors_aux
    0000000000600e18 t __do_global_dtors_aux_fini_array_entry
    0000000000601030 D __dso_handle
    0000000000600e28 d _DYNAMIC
    0000000000601038 D _edata
    0000000000601040 B _end
    00000000004005c4 T _fini
    0000000000400500 t frame_dummy
    0000000000600e10 t __frame_dummy_init_array_entry
    0000000000400708 r __FRAME_END__
    0000000000601000 d _GLOBAL_OFFSET_TABLE_
                     w __gmon_start__
    00000000004005e4 r __GNU_EH_FRAME_HDR
    00000000004003c8 T _init
    0000000000600e18 t __init_array_end
    0000000000600e10 t __init_array_start
    00000000004005d0 R _IO_stdin_used
                     w _ITM_deregisterTMCloneTable
                     w _ITM_registerTMCloneTable
    0000000000600e20 d __JCR_END__
    0000000000600e20 d __JCR_LIST__
                     w _Jv_RegisterClasses
    00000000004005c0 T __libc_csu_fini
    0000000000400550 T __libc_csu_init
                     U __libc_start_main@@GLIBC_2.2.5
    0000000000400526 T main
                     U puts@@GLIBC_2.2.5
    00000000004004a0 t register_tm_clones
    0000000000400430 T _start
    0000000000601038 D __TMC_END__

man

  • NM(1)                                     GNU Development Tools                                     NM(1)
    
    NAME
           nm - list symbols from object files
    
    SYNOPSIS
           nm [-A|-o|--print-file-name] [-a|--debug-syms]
              [-B|--format=bsd] [-C|--demangle[=style]]
              [-D|--dynamic] [-fformat|--format=format]
              [-g|--extern-only] [-h|--help]
              [-l|--line-numbers] [-n|-v|--numeric-sort]
              [-P|--portability] [-p|--no-sort]
              [-r|--reverse-sort] [-S|--print-size]
              [-s|--print-armap] [-t radix|--radix=radix]
              [-u|--undefined-only] [-V|--version]
              [-X 32_64] [--defined-only] [--no-demangle]
              [--plugin name] [--size-sort] [--special-syms]
              [--synthetic] [--target=bfdname]
              [objfile...]
    
    DESCRIPTION
           GNU nm lists the symbols from object files objfile....  If no object files are listed as
           arguments, nm assumes the file a.out.
    
           For each symbol, nm shows:
    
           ·   The symbol value, in the radix selected by options (see below), or hexadecimal by default.
    
           ·   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 ("u", "v" and "w").
    
               "A" The symbol's value is absolute, and will not be changed by further linking.
    
               "B"
               "b" The symbol is in the uninitialized data section (known as BSS).
    
               "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.
    
               "D"
               "d" The symbol is in the initialized data section.
    
               "G"
               "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.
    
               "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.
    
               "I" The symbol is an indirect reference to another symbol.
    
               "N" The symbol is a debugging symbol.
    
               "p" The symbols is in a stack unwind section.
    
               "R"
               "r" The symbol is in a read only data section.
    
               "S"
               "s" The symbol is in an uninitialized data section for small objects.
    
               "T"
               "t" The symbol is in the text (code) section.
    
               "U" The symbol is undefined.
    
               "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.
    
               "V"
               "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.
    
               "W"
               "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.
    
               "-" 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.
    
               "?" The symbol type is unknown, or object file format specific.
    
           ·   The symbol name.
    
    OPTIONS
           The long and short forms of options, shown here as alternatives, are equivalent.
    
           -A
           -o
           --print-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.
    
           -a
           --debug-syms
               Display all symbols, even debugger-only symbols; normally these are not listed.
    
           -B  The same as --format=bsd (for compatibility with the MIPS nm).
    
           -C
           --demangle[=style]
               Decode (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.
    
           --no-demangle
               Do not demangle low-level symbol names.  This is the default.
    
           -D
           --dynamic
               Display the dynamic symbols rather than the normal symbols.  This is only meaningful for
               dynamic objects, such as certain types of shared libraries.
    
           -f format
           --format=format
               Use the output format format, which can be "bsd", "sysv", or "posix".  The default is "bsd".
               Only the first character of format is significant; it can be either upper or lower case.
    
           -g
           --extern-only
               Display only external symbols.
    
           -h
           --help
               Show a summary of the options to nm and exit.
    
           -l
           --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.
    
           -n
           -v
           --numeric-sort
               Sort symbols numerically by their addresses, rather than alphabetically by their names.
    
           -p
           --no-sort
               Do not bother to sort the symbols in any order; print them in the order encountered.
    
           -P
           --portability
               Use the POSIX.2 standard output format instead of the default format.  Equivalent to -f posix.
    
           -r
           --reverse-sort
               Reverse the order of the sort (whether numeric or alphabetic); let the last come first.
    
           -S
           --print-size
               Print both value and size of defined symbols for the "bsd" output style.  This option has no
               effect for object formats that do not record symbol sizes, unless --size-sort is also used in
               which case a calculated size is displayed.
    
           -s
           --print-armap
               When listing symbols from archive members, include the index: a mapping (stored in the archive
               by ar or ranlib) of which modules contain definitions for which names.
    
           -t radix
           --radix=radix
               Use radix as the radix for printing the symbol values.  It must be d for decimal, o for octal,
               or x for hexadecimal.
    
           -u
           --undefined-only
               Display only undefined symbols (those external to each object file).
    
           -V
           --version
               Show the version number of nm and exit.
    
           -X  This option is ignored for compatibility with the AIX version of nm.  It takes one parameter
               which must be the string 32_64.  The default mode of AIX nm corresponds to -X 32, which is not
               supported by GNU nm.
    
           --defined-only
               Display only defined symbols for each object file.
    
           --plugin name
               Load the plugin called name to add support for extra target types.  This option is only
               available if the toolchain has been built with plugin support enabled.
    
           --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.  If the "bsd" output format is used
               the size of the symbol is printed, rather than the value, and -S must be used in order both
               size and value to be printed.
    
           --special-syms
               Display symbols which have a target-specific special meaning.  These symbols are usually used
               by the target for some special processing and are not normally helpful when included in the
               normal symbol lists.  For example for ARM targets this option would skip the mapping symbols
               used to mark transitions between ARM code, THUMB code and data.
    
           --synthetic
               Include synthetic symbols in the output.  These are special symbols created by the linker for
               various purposes.  They are not shown by default since they are not part of the binary's
               original source code.
    
           --target=bfdname
               Specify an object code format other than your system's default format.
    
           @file
               Read command-line options from file.  The options read are inserted in place of the original
               @file option.  If file does not exist, or cannot be read, then the option will be treated
               literally, and not removed.
    
               Options in file are separated by whitespace.  A whitespace character may be included in an
               option by surrounding the entire option in either single or double quotes.  Any character
               (including a backslash) may be included by prefixing the character to be included with a
               backslash.  The file may itself contain additional @file options; any such options will be
               processed recursively.
    
    SEE ALSO
           ar(1), objdump(1), ranlib(1), and the Info entries for binutils.
    
    COPYRIGHT
           Copyright (c) 1991-2015 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".
    
    binutils-2.26.1                                 2016-06-29                                          NM(1)

関連

参考