Python - IOError: [Errno 2] No such file or directory: u'lastid.py' for file in same directory. Works locally, doesn't on Heroku

Question

I suspect this is a very newbie question but I can\'t find any solutions that are helping :( I\'ve been trying to get started with Python by building a simple Twitter bot w

Answer 1

Probably the python interpreter is being executed from a different directory than where your script lives.

Here's the same setup:

oliver@aldebaran /tmp/junk $ cat test.txt 
a
b
c
baseoliver@aldebaran /tmp/junk $ cat sto.py 
with open('test.txt', 'r') as f:
    for line in f:
        print(line)
baseoliver@aldebaran /tmp/junk $ python sto.py 
a

b

c

baseoliver@aldebaran /tmp/junk $ cd ..
baseoliver@aldebaran /tmp $ python ./junk/sto.py 
Traceback (most recent call last):
  File "./junk/sto.py", line 1, in <module>
    with open('test.txt', 'r') as f:
IOError: [Errno 2] No such file or directory: 'test.txt'

To solve this, import os and use absolute pathnames:

import os
MYDIR = os.path.dirname(__file__)
with open(os.path.join(MYDIR, 'test.txt')) as f:
    pass
    # and so on