How do I get a backtrace from a crashing program ?

Here's how to get a backtrace from a crashing program :

Make sure you have gdb installed.
Compile the program with debugging options (usually -g). If the program uses autoconf :

 ./configure --enable-debug ; make clean ; make

Or simply add "-g" to the compiler options (these options are usually contained in an environment variable called CFLAGS for C or CXXFLAGS for C++).

  gdb ./program
  run

Produce the crash.
Type "bt" in the gdb console, this will output a backtrace showing exactly where the crash happens.