1<html lang="en"> 2<head> 3<title>nm - GNU Binary Utilities</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="GNU Binary Utilities"> 6<meta name="generator" content="makeinfo 4.13"> 7<link title="Top" rel="start" href="index.html#Top"> 8<link rel="prev" href="ar.html#ar" title="ar"> 9<link rel="next" href="objcopy.html#objcopy" title="objcopy"> 10<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 11<!-- 12Copyright (C) 1991-2013 Free Software Foundation, Inc. 13 14Permission is granted to copy, distribute and/or modify this document 15under the terms of the GNU Free Documentation License, Version 1.3 16or any later version published by the Free Software Foundation; 17with no Invariant Sections, with no Front-Cover Texts, and with no 18Back-Cover Texts. A copy of the license is included in the 19section entitled ``GNU Free Documentation License''. 20 21--> 22<meta http-equiv="Content-Style-Type" content="text/css"> 23<style type="text/css"><!-- 24 pre.display { font-family:inherit } 25 pre.format { font-family:inherit } 26 pre.smalldisplay { font-family:inherit; font-size:smaller } 27 pre.smallformat { font-family:inherit; font-size:smaller } 28 pre.smallexample { font-size:smaller } 29 pre.smalllisp { font-size:smaller } 30 span.sc { font-variant:small-caps } 31 span.roman { font-family:serif; font-weight:normal; } 32 span.sansserif { font-family:sans-serif; font-weight:normal; } 33--></style> 34<link rel="stylesheet" type="text/css" href="../cs.css"> 35</head> 36<body> 37<div class="node"> 38<a name="nm"></a> 39<p> 40Next: <a rel="next" accesskey="n" href="objcopy.html#objcopy">objcopy</a>, 41Previous: <a rel="previous" accesskey="p" href="ar.html#ar">ar</a>, 42Up: <a rel="up" accesskey="u" href="index.html#Top">Top</a> 43<hr> 44</div> 45 46<h2 class="chapter">2 nm</h2> 47 48<p><a name="index-symbols-36"></a><a name="index-nm-37"></a> 49<!-- man title nm list symbols from object files --> 50 51<pre class="smallexample"> <!-- man begin SYNOPSIS nm --> 52 nm [<samp><span class="option">-A</span></samp>|<samp><span class="option">-o</span></samp>|<samp><span class="option">--print-file-name</span></samp>] [<samp><span class="option">-a</span></samp>|<samp><span class="option">--debug-syms</span></samp>] 53 [<samp><span class="option">-B</span></samp>|<samp><span class="option">--format=bsd</span></samp>] [<samp><span class="option">-C</span></samp>|<samp><span class="option">--demangle</span></samp>[=<var>style</var>]] 54 [<samp><span class="option">-D</span></samp>|<samp><span class="option">--dynamic</span></samp>] [<samp><span class="option">-f</span></samp><var>format</var>|<samp><span class="option">--format=</span></samp><var>format</var>] 55 [<samp><span class="option">-g</span></samp>|<samp><span class="option">--extern-only</span></samp>] [<samp><span class="option">-h</span></samp>|<samp><span class="option">--help</span></samp>] 56 [<samp><span class="option">-l</span></samp>|<samp><span class="option">--line-numbers</span></samp>] [<samp><span class="option">-n</span></samp>|<samp><span class="option">-v</span></samp>|<samp><span class="option">--numeric-sort</span></samp>] 57 [<samp><span class="option">-P</span></samp>|<samp><span class="option">--portability</span></samp>] [<samp><span class="option">-p</span></samp>|<samp><span class="option">--no-sort</span></samp>] 58 [<samp><span class="option">-r</span></samp>|<samp><span class="option">--reverse-sort</span></samp>] [<samp><span class="option">-S</span></samp>|<samp><span class="option">--print-size</span></samp>] 59 [<samp><span class="option">-s</span></samp>|<samp><span class="option">--print-armap</span></samp>] [<samp><span class="option">-t</span></samp> <var>radix</var>|<samp><span class="option">--radix=</span></samp><var>radix</var>] 60 [<samp><span class="option">-u</span></samp>|<samp><span class="option">--undefined-only</span></samp>] [<samp><span class="option">-V</span></samp>|<samp><span class="option">--version</span></samp>] 61 [<samp><span class="option">-X 32_64</span></samp>] [<samp><span class="option">--defined-only</span></samp>] [<samp><span class="option">--no-demangle</span></samp>] 62 [<samp><span class="option">--plugin</span></samp> <var>name</var>] [<samp><span class="option">--size-sort</span></samp>] [<samp><span class="option">--special-syms</span></samp>] 63 [<samp><span class="option">--synthetic</span></samp>] [<samp><span class="option">--target=</span></samp><var>bfdname</var>] 64 [<var>objfile</var>...] 65 <!-- man end --> 66</pre> 67 <!-- man begin DESCRIPTION nm --> 68 <p><span class="sc">gnu</span> <samp><span class="command">nm</span></samp> lists the symbols from object files <var>objfile</var><small class="dots">...</small>. 69If no object files are listed as arguments, <samp><span class="command">nm</span></samp> assumes the file 70<samp><span class="file">a.out</span></samp>. 71 72 <p>For each symbol, <samp><span class="command">nm</span></samp> shows: 73 74 <ul> 75<li>The symbol value, in the radix selected by options (see below), or 76hexadecimal by default. 77 78 <li>The symbol type. At least the following types are used; others are, as 79well, depending on the object file format. If lowercase, the symbol is 80usually local; if uppercase, the symbol is global (external). There 81are however a few lowercase symbols that are shown for special global 82symbols (<code>u</code>, <code>v</code> and <code>w</code>). 83 84 <!-- Some more detail on exactly what these symbol types are used for --> 85 <!-- would be nice. --> 86 <dl> 87<dt><code>A</code><dd>The symbol's value is absolute, and will not be changed by further 88linking. 89 90 <br><dt><code>B</code><dt><code>b</code><dd>The symbol is in the uninitialized data section (known as BSS). 91 92 <br><dt><code>C</code><dd>The symbol is common. Common symbols are uninitialized data. When 93linking, multiple common symbols may appear with the same name. If the 94symbol is defined anywhere, the common symbols are treated as undefined 95references. 96For more details on common symbols, see the discussion of 97–warn-common in <a href="../ld/Options.html#Options">Linker options</a>. 98 99 <br><dt><code>D</code><dt><code>d</code><dd>The symbol is in the initialized data section. 100 101 <br><dt><code>G</code><dt><code>g</code><dd>The symbol is in an initialized data section for small objects. Some 102object file formats permit more efficient access to small data objects, 103such as a global int variable as opposed to a large global array. 104 105 <br><dt><code>i</code><dd>For PE format files this indicates that the symbol is in a section 106specific to the implementation of DLLs. For ELF format files this 107indicates that the symbol is an indirect function. This is a GNU 108extension to the standard set of ELF symbol types. It indicates a 109symbol which if referenced by a relocation does not evaluate to its 110address, but instead must be invoked at runtime. The runtime 111execution will then return the value to be used in the relocation. 112 113 <br><dt><code>I</code><dd>The symbol is an indirect reference to another symbol. 114 115 <br><dt><code>N</code><dd>The symbol is a debugging symbol. 116 117 <br><dt><code>p</code><dd>The symbols is in a stack unwind section. 118 119 <br><dt><code>R</code><dt><code>r</code><dd>The symbol is in a read only data section. 120 121 <br><dt><code>S</code><dt><code>s</code><dd>The symbol is in an uninitialized data section for small objects. 122 123 <br><dt><code>T</code><dt><code>t</code><dd>The symbol is in the text (code) section. 124 125 <br><dt><code>U</code><dd>The symbol is undefined. 126 127 <br><dt><code>u</code><dd>The symbol is a unique global symbol. This is a GNU extension to the 128standard set of ELF symbol bindings. For such a symbol the dynamic linker 129will make sure that in the entire process there is just one symbol with 130this name and type in use. 131 132 <br><dt><code>V</code><dt><code>v</code><dd>The symbol is a weak object. When a weak defined symbol is linked with 133a normal defined symbol, the normal defined symbol is used with no error. 134When a weak undefined symbol is linked and the symbol is not defined, 135the value of the weak symbol becomes zero with no error. On some 136systems, uppercase indicates that a default value has been specified. 137 138 <br><dt><code>W</code><dt><code>w</code><dd>The symbol is a weak symbol that has not been specifically tagged as a 139weak object symbol. When a weak defined symbol is linked with a normal 140defined symbol, the normal defined symbol is used with no error. 141When a weak undefined symbol is linked and the symbol is not defined, 142the value of the symbol is determined in a system-specific manner without 143error. On some systems, uppercase indicates that a default value has been 144specified. 145 146 <br><dt><code>-</code><dd>The symbol is a stabs symbol in an a.out object file. In this case, the 147next values printed are the stabs other field, the stabs desc field, and 148the stab type. Stabs symbols are used to hold debugging information. 149 150 <br><dt><code>?</code><dd>The symbol type is unknown, or object file format specific. 151</dl> 152 153 <li>The symbol name. 154</ul> 155 156<!-- man end --> 157<!-- man begin OPTIONS nm --> 158 <p>The long and short forms of options, shown here as alternatives, are 159equivalent. 160 161 <dl> 162<dt><samp><span class="env">-A</span></samp><dt><samp><span class="env">-o</span></samp><dt><samp><span class="env">--print-file-name</span></samp><dd><a name="index-input-file-name-38"></a><a name="index-file-name-39"></a><a name="index-source-file-name-40"></a>Precede each symbol by the name of the input file (or archive member) 163in which it was found, rather than identifying the input file once only, 164before all of its symbols. 165 166 <br><dt><samp><span class="env">-a</span></samp><dt><samp><span class="env">--debug-syms</span></samp><dd><a name="index-debugging-symbols-41"></a>Display all symbols, even debugger-only symbols; normally these are not 167listed. 168 169 <br><dt><samp><span class="env">-B</span></samp><dd><a name="index-g_t_0040command_007bnm_007d-format-42"></a><a name="index-g_t_0040command_007bnm_007d-compatibility-43"></a>The same as <samp><span class="option">--format=bsd</span></samp> (for compatibility with the MIPS <samp><span class="command">nm</span></samp>). 170 171 <br><dt><samp><span class="env">-C</span></samp><dt><samp><span class="env">--demangle[=</span><var>style</var><span class="env">]</span></samp><dd><a name="index-demangling-in-nm-44"></a>Decode (<dfn>demangle</dfn>) low-level symbol names into user-level names. 172Besides removing any initial underscore prepended by the system, this 173makes C++ function names readable. Different compilers have different 174mangling styles. The optional demangling style argument can be used to 175choose an appropriate demangling style for your compiler. See <a href="c_002b_002bfilt.html#c_002b_002bfilt">c++filt</a>, 176for more information on demangling. 177 178 <br><dt><samp><span class="env">--no-demangle</span></samp><dd>Do not demangle low-level symbol names. This is the default. 179 180 <br><dt><samp><span class="env">-D</span></samp><dt><samp><span class="env">--dynamic</span></samp><dd><a name="index-dynamic-symbols-45"></a>Display the dynamic symbols rather than the normal symbols. This is 181only meaningful for dynamic objects, such as certain types of shared 182libraries. 183 184 <br><dt><samp><span class="env">-f </span><var>format</var></samp><dt><samp><span class="env">--format=</span><var>format</var></samp><dd><a name="index-g_t_0040command_007bnm_007d-format-46"></a><a name="index-g_t_0040command_007bnm_007d-compatibility-47"></a>Use the output format <var>format</var>, which can be <code>bsd</code>, 185<code>sysv</code>, or <code>posix</code>. The default is <code>bsd</code>. 186Only the first character of <var>format</var> is significant; it can be 187either upper or lower case. 188 189 <br><dt><samp><span class="env">-g</span></samp><dt><samp><span class="env">--extern-only</span></samp><dd><a name="index-external-symbols-48"></a>Display only external symbols. 190 191 <br><dt><samp><span class="env">-h</span></samp><dt><samp><span class="env">--help</span></samp><dd>Show a summary of the options to <samp><span class="command">nm</span></samp> and exit. 192 193 <br><dt><samp><span class="env">-l</span></samp><dt><samp><span class="env">--line-numbers</span></samp><dd><a name="index-symbol-line-numbers-49"></a>For each symbol, use debugging information to try to find a filename and 194line number. For a defined symbol, look for the line number of the 195address of the symbol. For an undefined symbol, look for the line 196number of a relocation entry which refers to the symbol. If line number 197information can be found, print it after the other symbol information. 198 199 <br><dt><samp><span class="env">-n</span></samp><dt><samp><span class="env">-v</span></samp><dt><samp><span class="env">--numeric-sort</span></samp><dd>Sort symbols numerically by their addresses, rather than alphabetically 200by their names. 201 202 <br><dt><samp><span class="env">-p</span></samp><dt><samp><span class="env">--no-sort</span></samp><dd><a name="index-sorting-symbols-50"></a>Do not bother to sort the symbols in any order; print them in the order 203encountered. 204 205 <br><dt><samp><span class="env">-P</span></samp><dt><samp><span class="env">--portability</span></samp><dd>Use the POSIX.2 standard output format instead of the default format. 206Equivalent to ‘<samp><span class="samp">-f posix</span></samp>’. 207 208 <br><dt><samp><span class="env">-r</span></samp><dt><samp><span class="env">--reverse-sort</span></samp><dd>Reverse the order of the sort (whether numeric or alphabetic); let the 209last come first. 210 211 <br><dt><samp><span class="env">-S</span></samp><dt><samp><span class="env">--print-size</span></samp><dd>Print both value and size of defined symbols for the <code>bsd</code> output style. 212This option has no effect for object formats that do not record symbol 213sizes, unless ‘<samp><span class="samp">--size-sort</span></samp>’ is also used in which case a 214calculated size is displayed. 215 216 <br><dt><samp><span class="env">-s</span></samp><dt><samp><span class="env">--print-armap</span></samp><dd><a name="index-symbol-index_002c-listing-51"></a>When listing symbols from archive members, include the index: a mapping 217(stored in the archive by <samp><span class="command">ar</span></samp> or <samp><span class="command">ranlib</span></samp>) of which modules 218contain definitions for which names. 219 220 <br><dt><samp><span class="env">-t </span><var>radix</var></samp><dt><samp><span class="env">--radix=</span><var>radix</var></samp><dd>Use <var>radix</var> as the radix for printing the symbol values. It must be 221‘<samp><span class="samp">d</span></samp>’ for decimal, ‘<samp><span class="samp">o</span></samp>’ for octal, or ‘<samp><span class="samp">x</span></samp>’ for hexadecimal. 222 223 <br><dt><samp><span class="env">-u</span></samp><dt><samp><span class="env">--undefined-only</span></samp><dd><a name="index-external-symbols-52"></a><a name="index-undefined-symbols-53"></a>Display only undefined symbols (those external to each object file). 224 225 <br><dt><samp><span class="env">-V</span></samp><dt><samp><span class="env">--version</span></samp><dd>Show the version number of <samp><span class="command">nm</span></samp> and exit. 226 227 <br><dt><samp><span class="env">-X</span></samp><dd>This option is ignored for compatibility with the AIX version of 228<samp><span class="command">nm</span></samp>. It takes one parameter which must be the string 229<samp><span class="option">32_64</span></samp>. The default mode of AIX <samp><span class="command">nm</span></samp> corresponds 230to <samp><span class="option">-X 32</span></samp>, which is not supported by <span class="sc">gnu</span> <samp><span class="command">nm</span></samp>. 231 232 <br><dt><samp><span class="env">--defined-only</span></samp><dd><a name="index-external-symbols-54"></a><a name="index-undefined-symbols-55"></a>Display only defined symbols for each object file. 233 234 <br><dt><samp><span class="env">--plugin </span><var>name</var></samp><dd><a name="index-load-plugin-56"></a>Load the plugin called <var>name</var> to add support for extra target 235types. This option is only available if the toolchain has been built 236with plugin support enabled. 237 238 <br><dt><samp><span class="env">--size-sort</span></samp><dd>Sort symbols by size. The size is computed as the difference between 239the value of the symbol and the value of the symbol with the next higher 240value. If the <code>bsd</code> output format is used the size of the symbol 241is printed, rather than the value, and ‘<samp><span class="samp">-S</span></samp>’ must be used in order 242both size and value to be printed. 243 244 <br><dt><samp><span class="env">--special-syms</span></samp><dd>Display symbols which have a target-specific special meaning. These 245symbols are usually used by the target for some special processing and 246are not normally helpful when included in the normal symbol lists. 247For example for ARM targets this option would skip the mapping symbols 248used to mark transitions between ARM code, THUMB code and data. 249 250 <br><dt><samp><span class="env">--synthetic</span></samp><dd>Include synthetic symbols in the output. These are special symbols 251created by the linker for various purposes. They are not shown by 252default since they are not part of the binary's original source code. 253 254 <br><dt><samp><span class="env">--target=</span><var>bfdname</var></samp><dd><a name="index-object-code-format-57"></a>Specify an object code format other than your system's default format. 255See <a href="Target-Selection.html#Target-Selection">Target Selection</a>, for more information. 256 257 </dl> 258 259<!-- man end --> 260 </body></html> 261 262