Tracing python programs. Today, Evan Dandrea asked a general question "Where is set -x for python". A quick google for sys.settrace found: Some code snippets. I thought this was nice, but surely you want to be able to just trace an arbitrary program. So I present a 'quick hack' (5 minutes precisely :)) to do that based on the previous links final version:

#!/usr/bin/env python

 import linecache
import os
import os.path
import sys

 def traceit(frame, event, arg):
    if event == "line":
        lineno = frame.f_lineno
        filename = frame.f_globals["__file__"]
        if (filename.endswith(".pyc") or
            filename.endswith(".pyo")):
            filename = filename[:-1]
        name = frame.f_globals["__name__"]
        line = linecache.getline(filename, lineno)
        print "%s:%s: %s" % (name, lineno, line.rstrip())
    return traceit

 def main():
    search_path = os.environ.get('PATH',
        '').split(os.path.pathsep)
    argv = sys.argv[1:]
    if not argv:
        raise Exception("No command to trace supplied")
    args = argv[1:]
    command = argv[0]
    if os.path.sep not in command:
        for path in search_path:
            if os.path.exists(os.path.join(path, command)):
                command = os.path.join(path, command)
                break
    del sys.argv[0]
    source = open(command, 'rt')
    exec_symbols = dict(globals())
    exec_symbols['__name__'] = '__main__'
    sys.settrace(traceit)
    exec source in exec_symbols, exec_symbols

 main()