The typical usage to break into the debugger from a running program is to insert
import pdb; pdb.set_trace()
at the location you want to break into the debugger. You can then step through the code following this statement, and continue running without the debugger using the c command.
The typical usage to inspect a crashed program is:
>>> import pdb >>> import mymodule >>> mymodule.test() Traceback (most recent call last): File "<stdin>", line 1, in ? File "./mymodule.py", line 4, in test test2() File "./mymodule.py", line 3, in test2 print spam NameError: spam >>> pdb.pm() > ./mymodule.py(3)test2() -> print spam (Pdb) </stdin>