edit text file using Python

Question

I need to update a text file whenever my IP address changes, and then run a few commands from the shell afterwards.

1. Create variable LASTKNOWN = \"212.171.13

Answer 1

fileinput module has very ugly API, I find beautiful module for this task - in_place, example for Python 3:

import in_place

with in_place.InPlace('data.txt') as file:
    for line in file:
        line = line.replace('test', 'testZ')
        file.write(line)

main difference from fileinput:

• Instead of hijacking sys.stdout, a new filehandle is returned for writing.
• The filehandle supports all of the standard I/O methods, not just readline().

for example - fileinput can line by line editing only, in_pace allow read whole file to memory (if it not big) and modify it.