Create a file if it doesn't exist

Question

I\'m trying to open a file, and if the file doesn\'t exist, I need to create it and open it for writing. I have this so far:

#open file for reading
fn = input(\"         


        

Answer 1

Be warned, each time the file is opened with this method the old data in the file is destroyed regardless of 'w+' or just 'w'.

import os

with open("file.txt", 'w+') as f:
    f.write("file is opened for business")

Answer 2

Using input() implies Python 3, recent Python 3 versions have made the IOError exception deprecated (it is now an alias for OSError). So assuming you are using Python 3.3 or later:

fn = input('Enter file name: ')
try:
    file = open(fn, 'r')
except FileNotFoundError:
    file = open(fn, 'w')

Answer 3

If you don't need atomicity you can use os module:

import os

if not os.path.exists('/tmp/test'):
    os.mknod('/tmp/test')

UPDATE:

As Cory Klein mentioned, on Mac OS for using os.mknod() you need a root permissions, so if you are Mac OS user, you may use open() instead of os.mknod()

import os

if not os.path.exists('/tmp/test'):
    with open('/tmp/test', 'w'): pass