NMEDIT(1) NMEDIT(1)
NAME
nmedit - change global symbols to local symbols
SYNOPSIS
nmedit -s listfile [-R listfile] [-p] [-A] [-] [-arch archtype]
...] objectfile ... [-o output]
DESCRIPTION
Nmedit changes the global symbols not listed in the listfile file of
the -s listfile option to static symbols. Undefined symbols and com-
mon symbols are not effected and shouldn't be listed in listfile. 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 interfacesymbols -A executable
where the file interfacesymbols 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 interfacesymbols relocatable.o
which would leave only the symbols listed in the file interfacesymbols
(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 unde-
fined 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 archtype
Specifies the architecture, archtype, of the file for nmedit(1)
to process when the file is a universal file (see arch(3) for
the currently know archtypes). The archtype 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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