Breaking exceptions before stack unwind

[Chris Stankevitz <chris-01@stankevitz.com>]

According to the GDB documentation, you can tell gdb to break on all 
exceptions with this command:
  break __raise_exception

This does not work for me (not defined).  Others suggested this:
  break __cp_push_exception

That doesn't work for me either (not defined).

I have two questions:

1. Why don't either of those two options work for me?

2. What can I use to break on exceptions before the stack is unwound?

Thanks so much!

Chris

PS:

[chris@c4isr temp]$ nm a.out
080497a0 A __bss_start
0804846c t call_gmon_start
080497a0 b completed.1
0804976c d __CTOR_END__
08049768 d __CTOR_LIST__
          U __cxa_begin_catch@@CXXABI_1.2
          U __cxa_end_catch@@CXXABI_1.2
          U __cxa_rethrow@@CXXABI_1.2
0804967c D __data_start
0804967c W data_start
080485c8 t __do_global_ctors_aux
08048490 t __do_global_dtors_aux
08049680 D __dso_handle
08049774 d __DTOR_END__
08049770 d __DTOR_LIST__
08049688 D _DYNAMIC
080497a0 A _edata
080497a4 A _end
080485ec T _fini
0804967c A __fini_array_end
0804967c A __fini_array_start
08048608 R _fp_hw
080484cc t frame_dummy
08048664 r __FRAME_END__
0804977c D _GLOBAL_OFFSET_TABLE_
          w __gmon_start__
          U __gxx_personality_v0@@CXXABI_1.2
080483d0 T _init
0804967c A __init_array_end
0804967c A __init_array_start
0804860c R _IO_stdin_used
08049778 d __JCR_END__
08049778 d __JCR_LIST__
          w _Jv_RegisterClasses
08048584 T __libc_csu_fini
0804853c T __libc_csu_init
          U __libc_start_main@@GLIBC_2.0
080484f8 T main
08049684 d p.0
0804967c A __preinit_array_end
0804967c A __preinit_array_start
08048448 T _start
          U _Unwind_Resume@@GCC_3.0