Python sed simulation to add ##

In our normal work, we sometimes need to operate on a file, such as adding ##in front of each line of a file. In shell, this requirement is very simple, you can use the sed single line to solve the problem. Let's take a look at a file:

[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] #

It is very easy to use sed's single-line command to solve this requirement. Let's look at the Code:

[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] #

Let's take a look at the powerful sed. Next I will introduce you to how to use python to implement this operation that is often needed, and directly go to the Code:

[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 ')

The code is really simple. Let's see how it works:

[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

Haha, the effect is coming out, but there is a slight defect. We write the object file to be operated in the Code. How can we pass the file name as a parameter to the script? We need to modify it, to implement the following functions:
1. the file to be operated must be passed as a parameter to the script
2. Determine whether the operation object exists.
3. If the script runs incorrectly, a friendly prompt is required.
Based on the above requirements, the final version of the code is provided. The Code is as follows:

[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] #

Let's take a look at the various situations and effects:

[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] #

Now, the introduction of python is here. I will simulate some simple sed functions for you one after another.

This article from "you are a passer-by or huoyuanjia" blog, please be sure to keep this source http://world77.blog.51cto.com/414605/1348328