nmedit

NMEDIT(1)                    General Commands Manual                   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 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
       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.

       -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.

       -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), libtool(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 Inc.                        May 29, 2007                         NMEDIT(1)