#!/usr/bin/python
# -*- Coding: utf-8 -*-

import os
import sys

while True:
    cmd = raw_input('$ ').strip()
    if cmd == "exit": sys.exit(0)
    if cmd == "": continue
    pid = os.fork()
    if pid ==0:
        argv = cmd.split()
        try:
            os.execvp(argv[0], argv)
        except OSError:
            print >>sys.stderr,\
                "command not found: %s" \
                % argv[0]
            sys.exit(0)

    else:
        print "Wait for child (%d)" % pid
        res = os.wait()
        print "(%d) child quit with %d" % res