The GNU Debugger (GDB) is available on HECC systems in the /usr/bin directory. GDB can be used to debug programs written in C, C++, Fortran, and Modula-a.

GDB can perform four main tasks:

• Start your program, specifying anything that might affect its behavior.
• Make your program stop on specified conditions.
• Examine what happened when your program has stopped.
• Change things in your program, so you can experiment with correcting the effects of one bug and go on to learn about another.

Be sure to compile your code with -g for symbolic debugging.

GDB is typically used in the following ways:

• Start the debugger by itself:

  % gdb
  (gdb)

• Start the debugger and specify the executable:

  % gdb your_executable
  (gdb)

• Start the debugger, and specify the executable and core file:

  % gdb your_executable core-file
  (gdb)
  

• Attach gdb to a running process:

  %gdb your_executable pid
  (gdb)

At the prompt (gdb), enter commands such as break (for setting a breakpoint), run (to start running your executable, and step (for stepping into next line). Read man gdb to learn more on using gdb.