平时会对一些对系统文件或者目录的进行增删改查，这就需要用到python的一些库，例如os等
对文件进行操作
首先要先引入os
Import os
读写一个文件需要打开这个文件
可以用Open(dir,type)来操作，打开一个文件，或者写一个文件,中的目录如果在windows中路径需要用
”\” 双斜杠分隔，也可以用r来保持字符串中目录原路径r’c:/test.txt’
file = open(“c:\test.txt”,”w+”) #打开并对文件进行写操作
file = open(“c:\test.txt”,”r”) #打开并对文件进行读操作
删除一个文件可以用os.remove(dir,)
如果文件为只读的需要做一些其他的操作
引入stat
Import stat,os
os.chmod( filename, stat.S_IWRITE )
对一个目录（文件夹）进行操作
列出指定目录下的文件
import os
for filename in os.listdir(dir)
#操作
判断一个字符串是不是一个目录
利用os.isdir(dir)
遍历一个目录下的文件可以用walk
for root,dirs,files in os.walk(rootdir)
#
删除一个文件夹（里边可以有文件）可以用：
先要包含一个shutil
import shutil
shutil.rmtree(path)
上面一些基础的文件处理，下面我来介绍一个朋友写的文件创建，删除,修改处理类。
#!/usr/bin/env python
#encoding:utf-8 # 支持中文输入
import sys
import getpass
import shutil
import commands
import time
import fileinput
staff_list = 'contact_list.txt'
# 参数配置
user = 'admin'
passwd = '123456'
s = file(staff_list)
ss = s.readlines()
a = file(staff_list,'a')
counter = 0
_counter = 0
# 认证登陆
while True:
# 计数器,超过3次强制退出
if counter <= 3:
# 空用户名判断
name = raw_input("please input your name: ").strip()
if len(name) == 0:
print "empty name,try again!"
continue
# 用户名密码判断,密码隐藏
# pwd = raw_input("please input your password: ")
pwd = getpass.getpass('please input your password:')
if pwd == passwd and name == user:
print "Welcome to login,%s" %name
else:
print "name or password is not valid,please try again!"
counter +=1
continue
break
else:
print "exceeded 3 times user login..exit the script"
sys.exit()
# 选择增删改查
while True:
item = raw_input('''33[36;1mWelcome to login %s, what do you want to do?
-----------------------
press 'p' for print
press 'a' for add
press 'd' for delete
press 'u' for update
press 's' for select
press 'q' for quit
-----------------------
please make your choise: 33[0m''' % user)
# 打印所有
if item == 'p':
while True:
user_select = open(staff_list,'r')
s_ = user_select.read()
print ' '
print '33[32;1mThe content of the file33[0m '
print '33[32;1m--------------------------33[0m '
print s_
print '33[32;1m--------------------------33[0m '
print ' '
break
# 增加
elif item == 'a':
while True:
user_add_num = raw_input(("33[32;1mplease input your number: 33[0m ").strip())
user_add_name = raw_input(("33[32;1mplease input your name: 33[0m ").strip())
user_add_dept = raw_input(("33[32;1mplease input your department: 33[0m ").strip
())
user_add_id = raw_input(("33[32;1mplease input your id: 33[0m ").strip())
user_item = '%st%st%st%s' %(user_add_num,user_add_name,user_add_dept,user_add_id)
a.write("n%s" %user_item)
a.flush()
print "33[32;1mAdd item:33[0m"
print "33[32;1m------------------33[0m"
print user_item
print "33[32;1m------------------33[0m"
print "33[32;1mAdded successful!33[0m"
# 删除空行
del_blank_in = open('contact_list.txt','r')
del_blank_out = open('contact_list_new.txt','w')
lines = del_blank_in.readlines()
for blank in lines:
if blank.split():
del_blank_out.writelines(blank)
del_blank_in.close()
del_blank_out.close()
# 覆盖原文件
shutil.move('contact_list_new.txt','contact_list.txt')
user_add_choise = raw_input('press Q for quit or press any key to continue: ')
if user_add_choise == 'Q':
print 'bye!'
break
# 删除
elif item == 'd':
while True:
user_del_input = raw_input("please input sth to delete: ").strip()
if len(user_del_input) == 0:
print "empty input,try again!"
else:
# 输入值与源文件比对，有则丢弃，没有则添加到新文件，最后新文件覆盖源文件，实现删除
功能
with open('contact_list.txt','r') as ff:
with open('contact_list.txt.new','w') as gg:
for line in ff.readlines():
if user_del_input not in line:
gg.write(line)
if user_del_input in line:
print "33[32;1mDelete item:33[0m"
print "33[32;1m------------------33[0m"
print " %s " %line
_counter += 1 # 计数器,判断输入值命中次数
print "33[32;1m------------------33[0m"
print "33[32;1mDeleted successful!33[0m"
if _counter == 0:
print 'nothing delete!'
shutil.move('contact_list.txt.new','contact_list.txt')
# 退出删除
user_del_input_quit = raw_input("33[32;1mpress Q for quit or press any key to
continue? 33[0m").strip()
if user_del_input_quit == 'Q':
break
# 查询
elif item == 's':
while True:
match_yes = 0
#输入判断，忽略空格输入,加入颜色
user_select_input = raw_input("33[32;1mplease input sth to search:33[0m ").strip
()
contact_file = file (staff_list)
if len(user_select_input) == 0:
print "empty input,try again!"
else:
while True:
line = contact_file.readline()
if len(line) == 0:
break
if user_select_input in line:
match_yes = 1
print line
else:
pass
if match_yes == 0 :
print "No match item found"
# 退出查询
user_select_input_quit = raw_input("33[32;1mpress Q for quit or press any key to
continue? 33[0m").strip()
if user_select_input_quit == 'Q':
break
# 修改
elif item == 'u':
while True:
# 输入为空以及匹配查询内容判断
user_update_input_from = raw_input("33[32;1mplease search sth to update: 33
[0m").strip()
update_match = 0
update_file = file(staff_list).readlines()
for n_ in range(len(update_file)):
if user_update_input_from in update_file[n_]:
update_match = 1
else:
pass
if update_match == 0:
print "No match item found"
elif len(user_update_input_from) == 0:
print "empty input,try again!"
else:
# 将匹配到的字符修改为新字符
while True:
user_update_input_to = raw_input("33[32;1mupdate %s to what?33[0m " %
(user_update_input_from)).strip()
if len(user_update_input_to) == 0:
print "empty input,try again!"
else:
for line_ in fileinput.input(staff_list,inplace = 1,backup='.bak'):
line_ = line_.replace(user_update_input_from,user_update_input_to)
print line_
# 打印修改字符的行
print "33[32;1mupdate item:33[0m"
output_ = commands.getoutput("diff contact_list.txt contact_list.txt.bak|grep
'^>.*' | sed 's/^>//g'")
print "33[32;1m---------------------------33[0m"
print output_
print "33[32;1m---------------------------33[0m"
print "33[32;1mupdate successfully!33[0m"
# 删除空行
del_blank_in = open('contact_list.txt','r')
del_blank_out = open('contact_list_new.txt','w')
lines = del_blank_in.readlines()
for blank in lines:
if blank.split():
del_blank_out.writelines(blank)
del_blank_in.close()
del_blank_out.close()
# 覆盖原文件
shutil.move('contact_list_new.txt','contact_list.txt')
break
# 退出更新
user_update_input_quit = raw_input("33[32;1mpress Q for quit or press any key to
continue? 33[0m").strip()
if user_update_input_quit == 'Q':
break
# 退出
elif item == 'q':
print 'bye!'
sys.exit()
else:
print "33[31;1mnot a valid key word33[0m"
time.sleep(1)