STRIP(1)STRIP(1)NAMEstrip - remove symbols
SYNOPSISstrip [ option ] name ...
DESCRIPTIONstrip 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.
In NEXTSTEP 4.0, executable files can use the dynamic link editor. 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.
In NEXTSTEP 4.0, dynamic linking is done automatically with the dynamic
linker. 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
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 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 RLD(3)
In NEXTSTEP 3.3, dynamic linking files is done with rld(3), which is
still supported in NEXTSTEP 4.0. Trimming the symbol table for files
linked with rld(3) 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 objects loaded with rld 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
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 symbol 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.
-i Ignore symbols listed in the -s filename option 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
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 Objective-C class symbols. This is intended for
use of programs that use rld(3) 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 rld(3) 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).
And one last option:
- Treat all remaining arguments as file names and not options.
SEE ALSOld(1), rld(3), cc(1)LIMITATIONS
Not every layout of a Mach-O file can be stripped by this program. But
all layouts produced by the compiler system can be stripped.
NeXT Computer, Inc. April 11, 1995 STRIP(1)
