#!/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
    args = cmd.split()
    res = os.spawnvp(os.P_WAIT, args[0], args)
    if res==127: print >>sys.stderr,\
        "command not found: %s" % args[0]