trying to edit a text file

[snippsat]

I tried many iterations, wish I could remember all of them to post. I just tried f.close() at the end and it still didn't work.

It will not work as you try to do inplace of original file.
Look Gribouillis code it work as he use fileinput with inplace=True.

i am trying to replace the entire line as in replace "whiffenhard" with "woo"

Output of Grib code in fn.txt:

Output:
yipee

wahooo

woo

yerp

To get same output with menator01 code change line 9.

new_line = re.sub('whiffenhard', 'woo', line)

He dos a extra step make new list then overwrite original file,then avoid the inplace problem.

A third party module in-place

from in_place import InPlace.

with InPlace('fn.txt') as fp:
    for line in fp:
        line = line.replace('whiffenhard', 'woo')
        fp.write(line)

Output:
yipee

wahooo

woo

yerp