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

#!/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.

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

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:

#!/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):

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()

[sarrae1406]

Works nice, thanks !

[Mrityunj2018]

hi bvdet,

The script works fine for single file but how can i replace for multiple files in a directory .

could you write the script please .
My file extensions are .xlf
folder c:/mrit/

with kind regards,
MJ