Elaborating this answer, with pathlib you can use the as_posix method:

>>> import pathlib
>>> p = pathlib.PureWindowsPath(r'\dir\anotherdir\foodir\more')
>>> print(p)    
\dir\anotherdir\foodir\more
>>> print(p.as_posix())
/dir/anotherdir/foodir/more
>>> str(p)
'\\dir\\anotherdir\\foodir\\more'
>>> str(p.as_posix())
'/dir/anotherdir/foodir/more'

I recently found this and thought worth sharing:

import os

path = "C:\\temp\myFolder\example\\"
newPath = path.replace(os.sep, '/')
print(newPath)  # -> C:/temp/myFolder/example/

The second argument should be a string, not a regex pattern:

foo.replace(r'/DIR/', '\\\\MYDIR\\data\\')

You have to remember that strings in python are interpreted. Only raw strings do not follow this rule. Here I mean that if for example you have a "\n" included in your string, it would be interpreted as a new line. Fortunately strings read from file are already raw.

All you have to do is simply use the regular expression:

s.replace('\\','/')

Oh boy, this is a bit more complicated than first appears.

Your problem is that you have stored your windows paths as normal strings, instead of raw strings. The conversion from strings to their raw representation is lossy and ugly.

This is because when you make a string like "\a", the intperter sees a special character "\x07".

This means you have to manually know which of these special characters you expect, then [lossily] hack back if you see their representation (such as in this example):

def str_to_raw(s):
    raw_map = {8:r'\b', 7:r'\a', 12:r'\f', 10:r'\n', 13:r'\r', 9:r'\t', 11:r'\v'}
    return r''.join(i if ord(i) > 32 else raw_map.get(ord(i), i) for i in s)

>>> str_to_raw("\\ftac\admin\rec\pir")
'\\ftac\\admin\\rec\\pir'

Now you can use the pathlib module, this can handle paths in a system agnsotic way. In your case, you know you have Windows like paths as input, so you can use as follows:

import pathlib

def fix_path(path):
    # get proper raw representaiton
    path_fixed = str_to_raw(path)

    # read in as windows path, convert to posix string
    return pathlib.PureWindowsPath(path_fixed).as_posix()

>>> fix_path("\\ftac\admin\rec\pir")
'/ftac/admin/rec/pir'

Your \ is hiding the closing " so you need to use \\ - but python shouldn't care about the slashes in the path.

When you use a raw string, the backslash is no longer used as an escape character, and everything shows up in the string just as you typed it (you still can't end a string with a backslash, though). You only need to double it up if you're not using raw strings. Also, the result you saw was directly returned in an interactive session, which means you saw the repr of that string - meaning, it's telling you what you'd need to type in to produce the same object. Don't overdo it with raw strings and backslashes, and use print.

>>> myString = 'http://www.test.com/'
>>> print(mystring.replace('/', r'\/'))
http:\/\/www.test.com\/

Two backslashes mean a literal backslash:

s.replace("/", "\\")