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STRIP(1)							      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  sym‐
       bol 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	 relo‐
       cation 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 combined 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 typically 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 ref‐
       erenced 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 sym‐
       bols from the executable 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_symbols 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 executable 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_symbols	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 relo‐
	      catable objects to save symbols referred to by external  reloca‐
	      tion  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 symbol names listed in filename must be  one  per
	      line.  Leading and trailing white space are not part of the sym‐
	      bol 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 filename.	 The source file names listed in file‐
	      name 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 direc‐
	      tories.

       -A     Save  all	 global	 absolute symbols except those with a value of
	      zero, and save Objective C class symbols.	 This is intended  for
	      use  of  programs	 that load code at runtime 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 produced by the Apple compiler system can be stripped.

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