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OpenDarwin 7.2.1 - man page for strip (opendarwin section 1)

STRIP(1)			     General Commands Manual				 STRIP(1)

NAME
       strip - remove symbols

SYNOPSIS
       strip [ option ] name ...

DESCRIPTION
       strip  removes  or  modifies  the symbol table attached to the output of the assembler and
       link editor.  This is useful to save space after a program has been debugged and to  limit
       dynamically bound symbols.

       strip  no  longer removes relocation entries under any condition.  Instead, it updates the
       external relocation entries (and indirect symbol table entries) to reflect  the	resulting
       symbol table.  strip prints an error message for those symbols not in the resulting symbol
       table that are needed by an external relocation entry or an indirect  symbol  table.   The
       link  editor ld(1) is the only program that can strip relocation entries and know if it is
       safe to do so.

       When strip is used with no options on an executable file, it checks that file to see if it
       uses  the dynamic link editor.  If it does, the effect of the strip command is the same as
       using the -u and -r options. If the file does not use the dynamic link editor, the  effect
       of strip without any options is the same as using the -s option of ld(1).  The options -S,
       -x, and -X have the same effect as the ld(1) options.  The options to strip(1) can be com-
       bined to trim the symbol table to just what is desired.

       You  should  trim  the  symbol table of files used with dynamic linking so that only those
       symbols intended to be external interfaces are saved.  Files  used  with  dynamic  linking
       include	executables,  objects  that  are  loaded  (usually  bundles),  and dynamic shared
       libraries.  Only global symbols are used by the dynamic linking process. You should  strip
       all non-global symbols.

       When  an  executable is built with all its dependent dynamic shared libraries, it is typi-
       cally stripped with:
	      % strip -u -r executable
       which saves all undefined symbols (usually defined in the dynamic  shared  libraries)  and
       all  global  symbols  defined  in  the  executable referenced by the dynamic libraries (as
       marked by the static link editor when the executable was  built).   This  is  the  maximum
       level  of  striping  for  an executable that will still allow the program to run correctly
       with its libraries.

       If the executable loads objects, however, the global symbols that  the  objects	reference
       from  the  executable also must not be stripped.  In this case, you should list the global
       symbols that the executable wants to allow the objects to reference in a file,  and  those
       global symbols are then saved when the executable is stripped. For example:
	      % strip -u -r -s interface_symbols executable
       where  the  file  interface_symbols  would contain only those global symbols from the exe-
       cutable that the executable wants the loaded objects to have access to.

       For objects that will be loaded into an executable, you should trim the	symbol	table  to
       limit the global symbols the executable will see.  This would be done with:
	      % strip -s interface_symbols -u object
       which would leave only the undefined symbols and symbols listed in the file interface_sym-
       bols in the object file.  In this case, strip(1) has updated the  relocation  entries  and
       indirect symbol table to reflect the new symbol table.

       For  dynamic shared libraries, the maximum level of stripping is usually -x (to remove all
       non-global symbols).

STRIPPING FILES FOR USE WITH RUNTIME LOADED CODE
       Trimming the symbol table for programs that load code at runtime allows you to control the
       interface  that	the executable wants to provide to the objects that it will load; it will
       not have to publish symbols that are not part of its  interface.   For  example,  an  exe-
       cutable that wishes to allow only a subset of its global symbols but all of the statically
       linked shared library's globals to be used would be stripped with:
	      % strip -s interface_symbols -A executable
       where the file interface_symbols would contain only those symbols from the executable that
       it wishes the code 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 stripped with:
	      % ld -o relocatable.o -r a.o b.o c.o
	      % strip -s interface_symbols -u relocatable.o
       which would leave only the undefined symbols and symbols listed in the file interface_sym-
       bols in the object file.  In this case strip(1) has  updated  the  relocation  entries  to
       reflect the new symbol table.

OPTIONS
       The  first  set	of  options  indicate symbols that are to be save in the resulting output
       file.

       -u     Save all undefined symbols.  This is intended for use with relocatable  objects  to
	      save  symbols referred to by external relocation entries.  Note that common symbols
	      are also referred to by external relocation entries and this  flag  does	not  save
	      those symbols.

       -r     Save all symbols referenced dynamically.

       -s filename
	      Save  the symbol table entries for the global symbols listed in filename.  The sym-
	      bol 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
	      Remove the symbol table entries for the global symbols listed  in  filename.   This
	      file  has  the same format as the -s filename option above.  This option is usually
	      used in combination with other options that save some symbols, -S, -x, etc.

       -i     Ignore symbols listed in the -s filename or -R filename options that are not in the
	      files to be stripped (this is normally an error).

       -d filename
	      Save  the  debugging symbol table entries for each source file name listed in file-
	      name.  The source file names listed in filename must be one per line with no  other
	      white space in the file except the newlines on the end of each line.  And they must
	      be just the base name of the source file without any leading directories.

       -A     Save all global absolute symbols except those with a value of zero, and save Objec-
	      tive  C class symbols.  This is intended for use of programs that load code at run-
	      time and want the loaded code to use symbols from the  shared  libraries	(this  is
	      only used with NEXTSTEP 3.3 and earlier releases).

       -n     Save  all N_SECT global symbols.	This is intended for use with executable programs
	      in combination with -A to remove the symbols needed for correct static link editing
	      which  are  not  needed  for use with runtime loading interfaces where using the -s
	      filename would be too much trouble (this is only used with NEXTSTEP 3.3 and earlier
	      releases).

       These options specify symbols to be removed from the resulting output file.

       -S     Remove  the debugging symbol table entries (those created by the -g option to cc(1)
	      and other compilers).

       -X     Remove the local symbols whose names begin with `L'.

       -x     Remove all local symbols (saving only global symbols).

       -c     Remove the section contents of a dynamic library creating  a  stub  library  output
	      file.

       And the last options:

       -      Treat all remaining arguments as file names and not options.

       -o output
	      Write the result into the file output.

SEE ALSO
       ld(1), cc(1)

LIMITATIONS
       Not  every  layout of a Mach-O file can be stripped by this program.  But all layouts pro-
       duced by the Apple compiler system can be stripped.

Apple Computer, Inc.			  April 21, 2001				 STRIP(1)


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