nm






nm − list symbols from object files

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] [−−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] [−V|−−version]
   [−X 32_64] [−−defined−only] [−−no−demangle]
   [−−plugin name] [−−size−sort] [−−special−syms]
   [−−synthetic] [−−with−symbol−versions] [−−target=bfdname]
   [objfile...]

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"











                             ‐2‐


    "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.









                             ‐3‐


    "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.

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









                             ‐4‐


    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.

−−inlines
    When option −l is active, if the address belongs to a
    function that was inlined, then this option causes the
    source information for all enclosing scopes back to the
    first non‐inlined function to be printed as well.  For
    example, if "main" inlines "callee1" which inlines
    "callee2", and address is from "callee2", the source
    information for "callee1" and "main" will also be
    printed.

−n










                             ‐5‐


−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).











                             ‐6‐


−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.

    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.

−−size−sort
    Sort symbols by size.  For ELF objects symbol sizes are
    read from the ELF, for other object types the 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 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









                             ‐7‐


    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.

−−with−symbol−versions
    Enables the display of symbol version information if any
    exists.  The version string is displayed as a suffix to
    the symbol name, preceeded 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 preceeded
    by two @ characters.  For example foo@@VER_2.

−−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.

ar(1), objdump(1), ranlib(1), and the Info entries for
binutils.

Copyright (c) 1991−2018 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".