NM(1)

📦
version 2.47 · 3 versions
, in arch rolling

💅 nm(1) — GNU Development Tools

okay bestie, welcome to nm, aka the manual page for nm from the GNU Development Tools lineup. this is the tool that reads your object files and tells you what symbols are hiding in there. it's giving detective energy and honestly? iconic. let's get into it 🕵️‍♀️✨

✨ NAME ✨

nm — list symbols from object files

like, that's the whole job. it looks inside object files and lists out the symbols. simple queen behavior 👑

🌸 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]
   [--ifunc-chars=CHARS]
   [-j|--format=just-symbols]
   [-l|--line-numbers] [--inlines]
   [-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]
   [-U|--defined-only]
   [-V|--version]
   [-W|--no-weak]
   [-X 32_64]
   [--no-demangle]
   [--no-recurse-limit|--recurse-limit]]
   [--plugin name]
   [--size-sort]
   [--special-syms]
   [--synthetic]
   [--target=bfdname]
   [--unicode=method]
   [--with-symbol-versions]
   [--without-symbol-versions]
   [objfile...]

look at all those flags, she's got range 💅 (and yes, the ]] at the end of the recurse-limit line is exactly how it's written here — we don't fix, we report 🫡)

🦋 DESCRIPTION 🦋

GNU nm lists the symbols from object files objfile... . and here's the little detail that gets people every time: if no object files are listed as arguments, nm assumes the file a.out. no cap, it just goes looking for a.out on its own 🙈

so for each symbol, nm shows you a few things. let's break it down 🎀

⭐ what you get for every symbol

  • The symbol value, in the radix selected by options (see below), or hexadecimal by default.
  • The symbol type.
  • The symbol name. (plus version info if there is any — more on that at the bottom 👀)

💜 the symbol types (the alphabet lore)

At least the following types are used — others are used as well, depending on the object file format. and here's the vibe check rule: 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). exceptions to every rule, honestly main character energy 💀

  • A — The symbol's value is absolute, and will not be changed by further linking.
  • B, b — The symbol is in the BSS data section. This section typically contains zero-initialized or uninitialized data, although the exact behavior is system dependent.
  • C, 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. The lower case c character is used when the symbol is in a special section for small commons.
  • 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.

Note — the actual symbols display for GNU indirect symbols is controlled by the --ifunc-chars command line option. If this option has been provided then the first character in the string will be used for global indirect function symbols. If the string contains a second character then that will be used for local indirect function symbols.

  • I — The symbol is an indirect reference to another symbol.
  • N — The symbol is a debugging symbol.
  • n — The symbol is in a non-data, non-code, non-debug read-only section.
  • p — The symbol 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 or zero-initialized 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. one of one, literally 🔥
  • 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 + version tea

The symbol name. If a symbol has version information associated with it, then the version information is displayed as well. 💫

  • If the versioned symbol is undefined or hidden from linker, the version string is displayed as a suffix to the symbol name, preceded by an @ character. For example foo@VER_1.
  • If the version is the default version to be used when resolving unversioned references to the symbol, then it is displayed as a suffix preceded by two @ characters. For example foo@@VER_2.

double @ means default, single @ means the other thing. iykyk 🎀

more coming, bestie — don't go anywhere 🌈🫶

✨ OPTIONS ✨

okay bestie, real talk before we get into the flag buffet: the long and short forms of these options are equivalent — same energy, same result, pick whichever one feels cuter in your shell 💅

  • -A, -o, --print-file-name — puts the name of the input file (or archive member) in front of every symbol where it was found, instead of naming the input file just once before all its symbols. slay.
  • -a, --debug-syms — shows all the symbols, even the debugger-only ones. normally those don’t get listed at all, so this is the “no secrets” mode 🫶
  • -B — literally the same as --format=bsd, kept for compatibility with the MIPS version of nm.
  • -C, --demangle[=style] — decodes (demangles) those low-level symbol names into user-level names. it strips any initial underscore that the system prepended, and makes C++ function names actually readable. different compilers have different mangling styles, so the optional style argument lets you pick the right demangling style for your compiler ✨
  • --no-demangle — does not demangle low-level symbol names. this is the default, bestie.
  • --recurse-limit, --no-recurse-limit, --recursion-limit, --no-recursion-limit — turns a limit on or off for how much recursion happens while demangling strings. bc name mangling formats allow an infinite level of recursion, it’s possible to create strings whose decoding will exhaust the stack space available on the host machine and trigger a memory fault 😭 the limit tries to stop that by restricting recursion to 2048 levels of nesting. the default is for this limit to be enabled, but you might need to disable it to demangle truly complicated names. note: if you disable the recursion limit, stack exhaustion is possible, and bug reports about that kind of event will be rejected. like, read the room 💀
  • -D, --dynamic — shows the dynamic symbols instead of the normal symbols. this only actually means something for dynamic objects, like certain types of shared libraries.
  • -f format, --format=format — use the output format format, which can be "bsd", "sysv", "posix" or "just-symbols". the default is "bsd". only the first character of format is significant, and it can be upper or lower case. iconic.
  • -g, --extern-only — displays only external symbols. keeping it exclusive 💅
  • -h, --help — shows a summary of the options to nm and exits. the “help me help you” button.
  • --ifunc-chars=CHARS — when displaying GNU indirect function symbols, nm defaults to using the "i" character for both local indirect functions and global indirect functions. this option lets you specify a string with one or two characters: the first character is used for global indirect function symbols, and the second character (if present) is used for local indirect function symbols. custom lettering, no cap 🎀
  • -j — same as --format=just-symbols. simple, clean, just symbols.
  • -l, --line-numbers — for each symbol, tries to find a filename and line number using debugging information. for a defined symbol, it looks for the line number of the address of the symbol. for an undefined symbol, it looks for the line number of a relocation entry that refers to the symbol. if it finds line number info, it prints it after the other symbol info. detective mode 🔍
  • --inlines — when -l is active, if the address belongs to a function that was inlined, this option also prints the source information for all enclosing scopes back to the first non-inlined function. example: if "main" inlines "callee1" which inlines "callee2", and the address is from "callee2", the source info for "callee1" and "main" also gets printed. the whole family tree, exposed 🌸
  • -n, -v, --numeric-sort — sorts symbols numerically by their addresses, instead of alphabetically by their names. numbers first, letters later.
  • -p, --no-sort — does not bother sorting the symbols in any order; prints them in the order encountered. chaos mode, but make it intentional 💀
  • -P, --portability — uses the POSIX.2 standard output format instead of the default format. equivalent to -f posix.
  • -r, --reverse-sort — reverses the order of the sort (whether numeric or alphabetic); the last comes first. plot twist 🔥
  • -S, --print-size — prints both the value and the size of defined symbols for the "bsd" output style. this option has no effect for object formats that don’t record symbol sizes, unless --size-sort is also used — in that case a calculated size is displayed. math-ish, but make it cute.
  • -s, --print-armap — when listing symbols from archive members, includes the index: a mapping (stored in the archive by ar or ranlib) of which modules contain definitions for which names. the archive’s little address book 📖
  • -t radix, --radix=radix — uses radix as the radix for printing symbol values. it must be d for decimal, o for octal, or x for hexadecimal. pick your numeral vibe.
  • -u, --undefined-only — displays only undefined symbols (those external to each object file). by default, both defined and undefined symbols are displayed.
  • -U, --defined-only — displays only defined symbols for each object file. by default, both defined and undefined symbols are displayed. the mirror twin of -u 🪞
  • -V, --version — shows the version number of nm and exits. proof of identity.
  • -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. noted, bestie.
  • --plugin name — loads 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. if --plugin is not provided, but plugin support has been enabled, then nm iterates over the files in ${libdir}/bfd-plugins in alphabetic order and the first plugin that claims the object in question is used. please note that this plugin search directory is not the one used by ld’s -plugin option. in order to make nm use the linker plugin, it must be copied into the ${libdir}/bfd-plugins directory. for GCC-based compilations the linker plugin is called liblto_plugin.so.0.0.0; for Clang-based compilations it is called LLVMgold.so. the GCC plugin is always backwards compatible with earlier versions, so it is sufficient to just copy the newest one. plugin lore, unlocked 🔌
  • --size-sort — sorts symbols by size. for ELF objects, symbol sizes are read from the ELF; for other object types, symbol sizes are 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 for both size and value to be printed. note: this option does not work if --undefined-only has been enabled, because undefined symbols have no size. can’t measure what isn’t there, bestie 😭
  • --special-syms — displays symbols that 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 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. special little guys, handled.
  • --synthetic — includes synthetic symbols in the output. these are special symbols created by the linker for various purposes. they’re not shown by default since they’re not part of the binary’s original source code. manufactured, but make it visible ✨
  • --unicode=[default|invalid|locale|escape|hex|highlight] — controls the display of UTF-8 encoded multibyte characters in strings. the default (--unicode=default) gives them no special treatment. --unicode=locale displays the sequence in the current locale, which may or may not support them. --unicode=hex and --unicode=invalid display them as hex byte sequences enclosed by either angle brackets or curly braces. --unicode=escape displays them as escape sequences (\uxxxx), and --unicode=highlight displays them as escape sequences highlighted in red (if supported by the output device). the colouring is intended to draw attention to the presence of unicode sequences where they might not be expected. rainbow anxiety, but useful 🌈
  • -W, --no-weak — does not display weak symbols. weak symbols, respectfully, not invited.
  • --with-symbol-versions, --without-symbol-versions — enables or disables the display of symbol version information. the version string is displayed as a suffix to the symbol name, preceded by an @ character — for example foo@VER_1. if the version is the default version to be used when resolving unversioned references to the symbol, then it’s displayed as a suffix preceded by two @ characters — for example foo@@VER_2. by default, symbol version information is displayed. the @ situation is real 🎀
  • --target=bfdname — specifies an object code format other than your system’s default format. switching lanes.
  • @file — reads 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 is 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. file-ception, fr fr 📁

🌸 SEE ALSO 🌸

ar(1), objdump(1), ranlib(1), and the Info entries for binutils. go read the extended universe, iykyk 🫶

Copyright (c) 1991-2026 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".

💖 this iconic little page is from binutils-2.47, dated 2026-09-30 — and yes, NM(1) ate, no crumbs 💅

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