python模拟sed在每行添加##

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python模拟sed在每行添加##

科技探索者 2017-11-22 12:32:00 浏览525
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 我们在平常的工作中有时候需要对摸一个文件进行操作,比如在一个文件的每行前面添加##之类的,在shell中这个需求很简单,用sed单行就能搞定,下面我们来看看一个文件:

[root@host-192-168-209-128 py-sed]# cat a.txt
this is a text
this is use for python
this is also user for sed
this is a end test file
[root@host-192-168-209-128 py-sed]#
用sed的单行命令来搞定这个需求很简单,看下代码:
[root@host-192-168-209-128 py-sed]# sed 's/^/##/g' a.txt
##this is a text
##this is use for python
##this is also user for sed
##this is a end test file
[root@host-192-168-209-128 py-sed]#

看看,果然够强大的sed啊,下面我来给大家介绍介绍如何用python实现这个有时候经常需要的操作,直接上代码了:
[root@host-192-168-209-128 py-sed]# cat a.py
#!/usr/bin/env python

with open('a.txt') as f:
       con=f.readlines()
       for i in range(0,len(con)):
               print "###"+con[i].rstrip('\n')
代码实在很简单,看看效果如何吧:
[root@host-192-168-209-128 py-sed]# python a.py
###this is a text
###this is use for python
###this is also user for sed
###this is a end test file

呵呵,效果出来了吧,但是稍有缺陷,这个需要操作的对象文件我们是写死在代码里面的,如何把文件名作为参数传递给脚本呢,我们需要修改,以实现如下几个功能:
1. 需要把操作的文件作为参数传给脚本
2.需要对操作的对象进行判断,是否存在
3.如果脚本运行错误,需要有友好的提示效果
基于以上的需求,给出代码的最终版本,代码如下:

[root@host-192-168-209-128 py-sed]# cat tou.py
#!/usr/bin/env python
'''
edit by qhz
Email : world77@163.coom
This scrip to add "###" at every line for file

'''
def usage():
       print   '''
===============================================
This script to add "###" at every line for file
Use Example:
python script.py file
===============================================
'''
import sys
import os
if len(sys.argv) == 2:
        if os.path.isfile(sys.argv[1]):
                with open(sys.argv[1]) as f:
                       con=f.readlines()
                       for i in range(0,len(con)):
                              print '###'+con[i].strip('\n')
      else:
                print "==============================================="
                 print "Your input file name is not exit or not correct"
                 print "Please try again ,bye ..."
                 print "==============================================="
else:
          usage()
          exit()
[root@host-192-168-209-128 py-sed]#

下面来看看各种情况和效果:
[root@host-192-168-209-128 py-sed]# python tou.py

===============================================
This script to add "###" at every line for file
Use Example:
python script.py file
===============================================

[root@host-192-168-209-128 py-sed]# python tou.py a.tx
===============================================
Your input file name is not exit or not correct
Please try again ,bye ...
===============================================
[root@host-192-168-209-128 py-sed]# python tou.py a.txt
###this is a text
###this is use for python
###this is also user for sed
###this is a end test file
[root@host-192-168-209-128 py-sed]#
本文转自你是路人甲还是霍元甲博客51CTO博客,原文链接http://blog.51cto.com/world77/1348328如需转载请自行联系原作者

world77

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