Python to search text file string and replace it

DannyMc

Hi ,

i am in the middle of creating the script to match the string and replace it

in mount.txt
mickey:/work1 /work1 bla bla bla
mickey:/work2 /work2 bla bla bla
micket:/job /job bla bla bla

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#!/usr/bin/python

import string

s = open("/usr2/py/mount.txt","r+")

for line in s.readlines():

   print line

   string.replace(line, 'mickey','minnie')

   print line

s.close()

However, the string.replace seems not working, any advice??? Thank you!

I am using CentOS 4.6 and the python is 2.3.4

bvdet

Hello DannyMc,

string.replace() does not modify the argument string in place, but returns a modified string. You must make an assignment. Unless your file is very large, I would suggest updating the text in the file by reading the file, modifying the text, and writing the modified text back to the file. You can use string method replace() instead of importing the string module.

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 s = open("mount.txt").read()

s = s.replace('mickey', 'minnie')

f = open("mount.txt", 'w')

f.write(s)

f.close()

DannyMc

thanks for the solution bvdet!!

ghostdog74

you can use fileinput for inplace editing

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import fileinput

for line in fileinput.FileInput("file", inplace=1):

    line=line.replace("old","new")

    print line

DannyMc

Hi guys, i managed to solve my problem with the following scripts:

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#!/usr/bin/python

import re

#fstab location, use w mode as need to overwrite whole file.

s = open("/usr2/py/mount.txt","r")

#temp txt file to store new mount.

tmpfile = open("/usr2/py/tmp.txt","a")

#new nas mount point

newmount = open("/usr2/py/newmount.txt","r")

#search pg-swnas1 line

for line in s.readlines():

    if re.search("filer", line, re.IGNORECASE) != None:

        print line

    else:

        tmpfile.write(line)

#read the latest mount point

readmount = newmount.read()

#append to temp file

tmpfile.write(readmount)

s.close()

tmpfile.close()

tmpfile = open("/usr2/py/tmp.txt","r")

readtmp = tmpfile.read()

s = open("/usr2/py/mount.txt","w")

s.write(readtmp)
 
tmpfile.close()

newmount.close()

Though the code works, but it seems not a clean code. Is there anyway to simplify it???

bvdet

I am a bit unclear about what mount.txt and newmount.txt contain and what you need to replace. You do not need re. You can test for membership with the in operator. If I understand correctly, this should work (untested):

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 mountList = open("/usr2/py/mount.txt", "r").readlines()

newmountList = open("/usr2/py/newmount.txt","r").readlines()

outputList = [item for item in mountList if "filer" not in item.lower()]

outputList.extend(newmountList)

f = open("/usr2/py/mount.txt","w")

f.write(''.join(outputList))

f.close()

Python to search text file string and replace it

re: Python to search text file string and replace it

re: Python to search text file string and replace it

re: Python to search text file string and replace it

re: Python to search text file string and replace it

re: Python to search text file string and replace it

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