NMEDIT(1) General Commands Manual NMEDIT(1)
nmedit - change global symbols to local symbols
nmedit -s list_file [-R list_file] [-p] [-A] [-] [[-arch arch_type] ...]
object_file ... [-o output]
Nmedit changes the global symbols not listed in the list_file file of the
-s list_file option to static symbols. Undefined symbols and common
symbols are not affected and shouldn't be listed in list_file. For
dynamic libraries symbols are turned into private extern symbols that are
no longer external (rather than static symbols). This is done so that
the references between modules of a dynamic library are resolved to the
symbols in the dynamic library. Nmedit differs from strip(1) in that it
also changes the symbolic debugging information (produce by the -g option
to cc(1)) for the global symbols it changes to static symbols so that the
resulting object can still be used with the debugger.
Nmedit like strip(1) is useful to limit the symbols for use with later
linking. This allows control of the interface that the executable wants
to provide to the objects that it will dynamically load, and it will not
have to publish symbols that are not part of its interface. For example
an executable that wishes to allow only a subset of its global symbols
but all of the shared libraries globals to be used would have its symbol
table edited with:
% nmedit -s interface_symbols -A executable
where the file interface_symbols would contain only those symbols from
the executable that it wishes the objects loaded at runtime to have
access to. Another example is an object that is made up of a number of
other objects that will be loaded into an executable would built and then
have its symbol table edited with:
% ld -o relocatable.o -r a.o b.o c.o
% nmedit -s interface_symbols relocatable.o
which would leave only the symbols listed in the file interface_symbols
(and the undefined and common symbols) as global symbols in the object
The one or more of the following options is required to nmedit(1) is:
Leave the symbol table entries for the global symbols listed in
filename global but turn all other global symbols (except
undefined and common symbols) into static symbols. The symbol
names listed in filename must be one per line. Leading and
trailing white space are not part of the symbol name. Lines
starting with # are ignored, as are lines with only white space.
Change the symbol table entries for the global symbols listed in
filename into static symbols. This file has the same format as
the -s filename option above. If the -R filename option is
specified without the -s filename option, then all symbols not
listed in the -R filename option's filename are left as globals.
If both a -R filename and a -s filename are given the symbols
listed in the -R filename are basically ignored and only those
symbols listed in the -s filename are saved.
-p Change symbols to private externs instead of static. This is
allowed as the only option to change all defined global symbols to
The options to nmedit(1) are:
-A Leave all global absolute symbols except those with a value of
zero, and save objective-C class symbols as globals. This is
intended for use of programs that load code at runtime and want
the loaded code to use symbols from the shared libraries.
-D When editing a static library, set the archive's SYMDEF file's
user id, group id, date, and file mode to reasonable defaults. See
the libtool(1) documentation for -D for more information.
- Treat all remaining arguments as file names and not options.
Specifies the architecture, arch_type, of the file for nmedit(1)
to process when the file is a universal file (see arch(3) for the
currently know arch_types). The arch_type can be all to process
all architectures in the file. The default is to process all
architectures that are contained in the file.
Write the result into the file output.
strip(1), ld(1), libtool(1), arch(3)
The changing of the symbolic debugging information by nmedit is not known
to be totally correct and could cause the debugger to crash, get confused
or produce incorrect information.
Apple Inc. May 29, 2007 NMEDIT(1)