NMEDIT(1) NMEDIT(1)
NAME
nmedit - change global symbols to local symbols
SYNOPSIS
nmedit -s list_file [-R list_file] [-p] [-A] [-] [[-arch arch_type] ...] object_file ... [-o output]
DESCRIPTION
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 effected 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 exe-cutable executable
cutable 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 file.
The one or more of the following options is required to nmedit(1) is:
-s filename
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.
-R filename
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 private externs.
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.
- Treat all remaining arguments as file names and not options.
-arch arch_type
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.
-o output
Write the result into the file output.
SEE ALSO
strip(1), ld(1), arch(3)
BUGS
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 Computer, Inc. July 28, 2005 NMEDIT(1)
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