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<a name="nm"></a>
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Next: <a rel="next" accesskey="n" href="objcopy.html#objcopy">objcopy</a>,
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Previous: <a rel="previous" accesskey="p" href="ar.html#ar">ar</a>,
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<h2 class="chapter">2 nm</h2>
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<p><a name="index-symbols-38"></a><a name="index-nm-39"></a>
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<!-- man title nm list symbols from object files -->
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<pre class="smallexample"> <!-- man begin SYNOPSIS nm -->
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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>]
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[<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>]]
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[<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>]
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[<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>]
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[<samp><span class="option">-l</span></samp>|<samp><span class="option">--line-numbers</span></samp>] [<samp><span class="option">--inlines</span></samp>]
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[<samp><span class="option">-n</span></samp>|<samp><span class="option">-v</span></samp>|<samp><span class="option">--numeric-sort</span></samp>]
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[<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>]
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[<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>]
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[<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>]
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[<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>]
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[<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>]
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[<samp><span class="option">--plugin</span></samp> <var>name</var>]
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[<samp><span class="option">--no-recurse-limit</span></samp>|<samp><span class="option">--recurse-limit</span></samp>]]
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[<samp><span class="option">--size-sort</span></samp>] [<samp><span class="option">--special-syms</span></samp>]
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[<samp><span class="option">--synthetic</span></samp>] [<samp><span class="option">--with-symbol-versions</span></samp>] [<samp><span class="option">--target=</span></samp><var>bfdname</var>]
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[<var>objfile</var>...]
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<!-- man end -->
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</pre>
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<!-- man begin DESCRIPTION nm -->
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<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>.
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If no object files are listed as arguments, <samp><span class="command">nm</span></samp> assumes the file
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<samp><span class="file">a.out</span></samp>.
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<p>For each symbol, <samp><span class="command">nm</span></samp> shows:
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<ul>
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<li>The symbol value, in the radix selected by options (see below), or
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hexadecimal by default.
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<li>The symbol type. At least the following types are used; others are, as
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well, depending on the object file format. If lowercase, the symbol is
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usually local; if uppercase, the symbol is global (external). There
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are however a few lowercase symbols that are shown for special global
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symbols (<code>u</code>, <code>v</code> and <code>w</code>).
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<!-- Some more detail on exactly what these symbol types are used for -->
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<!-- would be nice. -->
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<dl>
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<dt><code>A</code><dd>The symbol's value is absolute, and will not be changed by further
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linking.
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<br><dt><code>B</code><dt><code>b</code><dd>The symbol is in the BSS data section. This section typically
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contains zero-initialized or uninitialized data, although the exact
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behavior is system dependent.
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<br><dt><code>C</code><dd>The symbol is common. Common symbols are uninitialized data. When
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linking, multiple common symbols may appear with the same name. If the
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symbol is defined anywhere, the common symbols are treated as undefined
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references.
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For more details on common symbols, see the discussion of
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–warn-common in <a href="../ld/Options.html#Options">Linker options</a>.
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<br><dt><code>D</code><dt><code>d</code><dd>The symbol is in the initialized data section.
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<br><dt><code>G</code><dt><code>g</code><dd>The symbol is in an initialized data section for small objects. Some
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object file formats permit more efficient access to small data objects,
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such as a global int variable as opposed to a large global array.
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<br><dt><code>i</code><dd>For PE format files this indicates that the symbol is in a section
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specific to the implementation of DLLs. For ELF format files this
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indicates that the symbol is an indirect function. This is a GNU
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extension to the standard set of ELF symbol types. It indicates a
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symbol which if referenced by a relocation does not evaluate to its
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address, but instead must be invoked at runtime. The runtime
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execution will then return the value to be used in the relocation.
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<br><dt><code>I</code><dd>The symbol is an indirect reference to another symbol.
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<br><dt><code>N</code><dd>The symbol is a debugging symbol.
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<br><dt><code>n</code><dd>The symbol is in the read-only data section.
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<br><dt><code>p</code><dd>The symbol is in a stack unwind section.
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<br><dt><code>R</code><dt><code>r</code><dd>The symbol is in a read only data section.
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<br><dt><code>S</code><dt><code>s</code><dd>The symbol is in an uninitialized or zero-initialized data section
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for small objects.
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<br><dt><code>T</code><dt><code>t</code><dd>The symbol is in the text (code) section.
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<br><dt><code>U</code><dd>The symbol is undefined.
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<br><dt><code>u</code><dd>The symbol is a unique global symbol. This is a GNU extension to the
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standard set of ELF symbol bindings. For such a symbol the dynamic linker
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will make sure that in the entire process there is just one symbol with
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this name and type in use.
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<br><dt><code>V</code><dt><code>v</code><dd>The symbol is a weak object. When a weak defined symbol is linked with
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a normal defined symbol, the normal defined symbol is used with no error.
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When a weak undefined symbol is linked and the symbol is not defined,
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the value of the weak symbol becomes zero with no error. On some
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systems, uppercase indicates that a default value has been specified.
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<br><dt><code>W</code><dt><code>w</code><dd>The symbol is a weak symbol that has not been specifically tagged as a
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weak object symbol. When a weak defined symbol is linked with a normal
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defined symbol, the normal defined symbol is used with no error.
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When a weak undefined symbol is linked and the symbol is not defined,
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the value of the symbol is determined in a system-specific manner without
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error. On some systems, uppercase indicates that a default value has been
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specified.
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<br><dt><code>-</code><dd>The symbol is a stabs symbol in an a.out object file. In this case, the
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next values printed are the stabs other field, the stabs desc field, and
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the stab type. Stabs symbols are used to hold debugging information.
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<br><dt><code>?</code><dd>The symbol type is unknown, or object file format specific.
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</dl>
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<li>The symbol name.
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</ul>
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<!-- man end -->
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<!-- man begin OPTIONS nm -->
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<p>The long and short forms of options, shown here as alternatives, are
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equivalent.
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<dl>
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<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-40"></a><a name="index-file-name-41"></a><a name="index-source-file-name-42"></a>Precede each symbol by the name of the input file (or archive member)
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in which it was found, rather than identifying the input file once only,
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before all of its symbols.
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<br><dt><samp><span class="env">-a</span></samp><dt><samp><span class="env">--debug-syms</span></samp><dd><a name="index-debugging-symbols-43"></a>Display all symbols, even debugger-only symbols; normally these are not
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listed.
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<br><dt><samp><span class="env">-B</span></samp><dd><a name="index-g_t_0040command_007bnm_007d-format-44"></a><a name="index-g_t_0040command_007bnm_007d-compatibility-45"></a>The same as <samp><span class="option">--format=bsd</span></samp> (for compatibility with the MIPS <samp><span class="command">nm</span></samp>).
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<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-46"></a>Decode (<dfn>demangle</dfn>) low-level symbol names into user-level names.
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Besides removing any initial underscore prepended by the system, this
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makes C++ function names readable. Different compilers have different
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mangling styles. The optional demangling style argument can be used to
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choose an appropriate demangling style for your compiler. See <a href="c_002b_002bfilt.html#c_002b_002bfilt">c++filt</a>,
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for more information on demangling.
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<br><dt><samp><span class="env">--no-demangle</span></samp><dd>Do not demangle low-level symbol names. This is the default.
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<br><dt><samp><span class="env">--recurse-limit</span></samp><dt><samp><span class="env">--no-recurse-limit</span></samp><dt><samp><span class="env">--recursion-limit</span></samp><dt><samp><span class="env">--no-recursion-limit</span></samp><dd>Enables or disables a limit on the amount of recursion performed
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whilst demangling strings. Since the name mangling formats allow for
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an inifinite level of recursion it is possible to create strings whose
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decoding will exhaust the amount of stack space available on the host
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machine, triggering a memory fault. The limit tries to prevent this
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from happening by restricting recursion to 2048 levels of nesting.
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<p>The default is for this limit to be enabled, but disabling it may be
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necessary in order to demangle truly complicated names. Note however
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that if the recursion limit is disabled then stack exhaustion is
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possible and any bug reports about such an event will be rejected.
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<br><dt><samp><span class="env">-D</span></samp><dt><samp><span class="env">--dynamic</span></samp><dd><a name="index-dynamic-symbols-47"></a>Display the dynamic symbols rather than the normal symbols. This is
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only meaningful for dynamic objects, such as certain types of shared
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libraries.
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<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-48"></a><a name="index-g_t_0040command_007bnm_007d-compatibility-49"></a>Use the output format <var>format</var>, which can be <code>bsd</code>,
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<code>sysv</code>, or <code>posix</code>. The default is <code>bsd</code>.
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Only the first character of <var>format</var> is significant; it can be
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either upper or lower case.
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<br><dt><samp><span class="env">-g</span></samp><dt><samp><span class="env">--extern-only</span></samp><dd><a name="index-external-symbols-50"></a>Display only external symbols.
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<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.
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<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-51"></a>For each symbol, use debugging information to try to find a filename and
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line number. For a defined symbol, look for the line number of the
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address of the symbol. For an undefined symbol, look for the line
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number of a relocation entry which refers to the symbol. If line number
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information can be found, print it after the other symbol information.
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<br><dt><samp><span class="env">--inlines</span></samp><dd><a name="index-objdump-inlines-52"></a>When option <samp><span class="option">-l</span></samp> is active, if the address belongs to a
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function that was inlined, then this option causes the source
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information for all enclosing scopes back to the first non-inlined
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function to be printed as well. For example, if <code>main</code> inlines
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<code>callee1</code> which inlines <code>callee2</code>, and address is from
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<code>callee2</code>, the source information for <code>callee1</code> and <code>main</code>
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will also be printed.
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<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
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by their names.
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<br><dt><samp><span class="env">-p</span></samp><dt><samp><span class="env">--no-sort</span></samp><dd><a name="index-sorting-symbols-53"></a>Do not bother to sort the symbols in any order; print them in the order
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encountered.
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<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.
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Equivalent to ‘<samp><span class="samp">-f posix</span></samp>’.
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<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
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last come first.
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<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.
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This option has no effect for object formats that do not record symbol
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sizes, unless ‘<samp><span class="samp">--size-sort</span></samp>’ is also used in which case a
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calculated size is displayed.
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<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-54"></a>When listing symbols from archive members, include the index: a mapping
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(stored in the archive by <samp><span class="command">ar</span></samp> or <samp><span class="command">ranlib</span></samp>) of which modules
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contain definitions for which names.
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<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
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‘<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.
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<br><dt><samp><span class="env">-u</span></samp><dt><samp><span class="env">--undefined-only</span></samp><dd><a name="index-external-symbols-55"></a><a name="index-undefined-symbols-56"></a>Display only undefined symbols (those external to each object file).
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<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.
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<br><dt><samp><span class="env">-X</span></samp><dd>This option is ignored for compatibility with the AIX version of
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<samp><span class="command">nm</span></samp>. It takes one parameter which must be the string
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<samp><span class="option">32_64</span></samp>. The default mode of AIX <samp><span class="command">nm</span></samp> corresponds
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to <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>.
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<br><dt><samp><span class="env">--defined-only</span></samp><dd><a name="index-external-symbols-57"></a><a name="index-undefined-symbols-58"></a>Display only defined symbols for each object file.
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<br><dt><samp><span class="env">--plugin </span><var>name</var></samp><dd><a name="index-plugins-59"></a>Load the plugin called <var>name</var> to add support for extra target
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types. This option is only available if the toolchain has been built
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with plugin support enabled.
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<p>If <samp><span class="option">--plugin</span></samp> is not provided, but plugin support has been
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enabled then <samp><span class="command">nm</span></samp> iterates over the files in
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<samp><span class="file">${libdir}/bfd-plugins</span></samp> in alphabetic order and the first
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plugin that claims the object in question is used.
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<p>Please note that this plugin search directory is <em>not</em> the one
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used by <samp><span class="command">ld</span></samp>'s <samp><span class="option">-plugin</span></samp> option. In order to make
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<samp><span class="command">nm</span></samp> use the linker plugin it must be copied into the
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<samp><span class="file">${libdir}/bfd-plugins</span></samp> directory. For GCC based compilations
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the linker plugin is called <samp><span class="file">liblto_plugin.so.0.0.0</span></samp>. For Clang
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based compilations it is called <samp><span class="file">LLVMgold.so</span></samp>. The GCC plugin
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is always backwards compatible with earlier versions, so it is
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sufficient to just copy the newest one.
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<br><dt><samp><span class="env">--size-sort</span></samp><dd>Sort symbols by size. For ELF objects symbol sizes are read from the
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ELF, for other object types the symbol sizes are computed as the
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difference between the value of the symbol and the value of the symbol
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with the next higher value. If the <code>bsd</code> output format is used
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the size of the symbol is printed, rather than the value, and
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‘<samp><span class="samp">-S</span></samp>’ must be used in order both size and value to be printed.
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<br><dt><samp><span class="env">--special-syms</span></samp><dd>Display symbols which have a target-specific special meaning. These
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symbols are usually used by the target for some special processing and
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are not normally helpful when included in the normal symbol lists.
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For example for ARM targets this option would skip the mapping symbols
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used to mark transitions between ARM code, THUMB code and data.
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<br><dt><samp><span class="env">--synthetic</span></samp><dd>Include synthetic symbols in the output. These are special symbols
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created by the linker for various purposes. They are not shown by
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default since they are not part of the binary's original source code.
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<br><dt><samp><span class="env">--with-symbol-versions</span></samp><dd>Enables the display of symbol version information if any exists. The
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version string is displayed as a suffix to the symbol name, preceeded by
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an @ character. For example ‘<samp><span class="samp">foo@VER_1</span></samp>’. If the version is
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|
the default version to be used when resolving unversioned references
|
|
to the symbol then it is displayed as a suffix preceeded by two @
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|
characters. For example ‘<samp><span class="samp">foo@@VER_2</span></samp>’.
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<br><dt><samp><span class="env">--target=</span><var>bfdname</var></samp><dd><a name="index-object-code-format-60"></a>Specify an object code format other than your system's default format.
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See <a href="Target-Selection.html#Target-Selection">Target Selection</a>, for more information.
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</dl>
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<!-- man end -->
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</body></html>
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