一个小巧的Python Shell

#!/usr/bin/python
# -*- coding: cp936 -*-

#################################
#   Written by caocao           #
#   caocao@eastday.com          #
#   http://nethermit.yeah.net   #
#################################

import os
import sys
import string
import re

print "Written by caocao"
print "caocao@eastday.com"
print "http://nethermit.yeah.net"
print

if os.name=="nt":
 print "OS: Windows NT"
else:
 print "OS: Unknown"
print "Python Shell Version 1.0"
print
while True:
 try:
  command=string.strip(raw_input("PS "+os.getcwd()+">"), " ")
  commandLow=string.lower(command)
 except EOFError:
  break
 else:
  if commandLow=="exit" or commandLow=="quit":
   break
  elif commandLow=="":
   continue
  elif re.match("^[a-z]{1}:$", command, re.I)!=None:
   try:
    os.chdir(command)
   except OSError:
    print "No such file or directory"
  elif re.match("^cd (.+)$", command, re.I)!=None:
   matchObject=re.search("^cd (.+)$", command, re.I)
   if matchObject!=None:
    try:
     os.chdir(matchObject.group(1))
    except OSError:
     print "No such file or directory"
   else:
    print "Bad command"
  else:
   os.system(command)
  print
print "Byebye!"