tina@lugosi:~$ cat mainloop 
#!/usr/bin/perl
use strict;
use warnings;
use Tk;
tkinit;
MainLoop;
tina@lugosi:~$ gdb perl mainloop 
GNU gdb 6.3-debian
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu"...(no debugging symbols found)
Using host libthread_db library "/lib/libthread_db.so.1".

"/home/tina/mainloop" is not a core dump: File format not recognized
(gdb)