python os模块进行文件的删除与重命名

#coding:utf-8
import os
import string

def replace(file, search_for, replace_with):
# replace strings in a text file
back = os.path.splitext(file)[0] + ".bak"
temp = os.path.splitext(file)[0] + ".tmp"
try:
# remove old temp file, if any
os.remove(temp)
except os.error:
pass
fi = open(file)
fo = open(temp, "w")
for s in fi.readlines():
fo.write(string.replace(s,search_for, replace_with))
fi.close()
fo.close()
try: #remove old backup file, if any
os.remove(back)
except os.error:
pass #rename original to backup...
os.rename(file,back) # ...and temporary to original
os.rename(temp,file)# #try it out!

file ="test.txt"
replace(file,"hello", "tjena2")
replace(file,"tjena", "hello2")