一個小巧的Python Shell

#!/usr/bin/python# -*- coding: cp936 -*-##################################   Written by caocao           ##   caocao@eastday.com          ##   http://nethermit.yeah.net   ##################################import osimport sysimport stringimport reprint "Written by caocao"print "caocao@eastday.com"print "http://nethermit.yeah.net"printif os.name=="nt": print "OS: Windows NT"else: print "OS: Unknown"print "Python Shell Version 1.0"printwhile 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)  printprint "Byebye!"