Correct way to check for empty or missing file in Python

Question

I want to check both whether a file exists and, if it does, if it is empty.

If the file doesn't exist, I want to exit the program with an error message.

If the file is empty I want to exit with a different error message.

Otherwise I want to continue.

I've been reading about using Try: Except: but I'm not sure how to structure the code 'Pythonically' to achieve what I'm after?

Thank you for all your responses, I went with the following code:

try:
    if os.stat(URLFilePath + URLFile).st_size > 0:
        print "Processing..."
    else:
        print "Empty URL file ... exiting"
        sys.exit()
except OSError:
    print "URL file missing ... exiting"
    sys.exit()

Just to clarify, the program is loading URLs from the file I'm checking, doing stuff with them, then zeroing out the file using `open(URLFile, 'w').close()`. I'm going to run the program every few minutes so I want it to exit if no new URLs have been added in the meantime. — TheRogueWolf, Jul 19 '13 at 13:55
possible duplicate of [python how to check file empty or not](http://stackoverflow.com/questions/2507808/python-how-to-check-file-empty-or-not) — Alex Kulinkovich, Dec 01 '14 at 14:05
Using exceptions for foreseeable and avoidable errors is lazy. Check if the file exists, and if it does, then check its size. — Richard Haven, Jun 11 '16 at 01:00

score 18 · Accepted Answer · edited Jul 19 '13 at 14:19

18

I'd use os.stat here:

try:
    if os.stat(filename).st_size > 0:
       print "All good"
    else:
       print "empty file"
except OSError:
    print "No file"

edited Jul 19 '13 at 14:19

TheRogueWolf

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answered Jul 19 '13 at 13:42

mgilson

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This is IMO the best solution. – Markus Unterwaditzer Jul 19 '13 at 13:46
what about zero byte files? – psukys Jul 19 '13 at 13:53
@shookees -- Forgive my ignorance, but how is a zero byte file different from an empty file? – mgilson Jul 19 '13 at 15:12
@TheRogueWolf -- Thanks for catching that. Too early to code apparently :) – mgilson Jul 19 '13 at 15:12

Tim Pietzcker · Answer 2 · 2013-07-19T13:37:47.183

2

How about this:

try:
    myfile = open(filename)
except IOError:  # FileNotFoundError in Python 3
    print "File not found: {}".format(filename)
    sys.exit()

contents = myfile.read()
myfile.close()

if not contents:
    print "File is empty!"
    sys.exit()

edited Jul 19 '13 at 13:37

answered Jul 19 '13 at 13:32

Tim Pietzcker

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Is `FileNotFoundError` a thing? (it isn't for me with python2.7 -- That just raises a `NameError`) For me it's an `IOError`. Also, I would discourage reading the entire file (what if the user accidentally provides a file which is 8 Gb?) I think you can get the empty/non-empty info from `os.stat`. – mgilson Jul 19 '13 at 13:37
@mgilson: Right; I tested `open("blargh")` in Python 3 and had expected the exception also to be present in Python 2. So my previous version was actually correct :) – Tim Pietzcker Jul 19 '13 at 13:39
Nice, I hadn't realized that they subclassed IOError and created FileNotFoundError in py3k. cool. – mgilson Jul 19 '13 at 13:43

Jakob Bowyer · Answer 3 · 2013-07-19T13:37:55.013

1

os.path.exists and other functions in os.path.

As for reading,

you want something like

if not os.path.exists(path):
    with open(path) as fi:
        if not fi.read(3):  #avoid reading entire file.
             print "File is empty"

edited Jul 19 '13 at 13:37

answered Jul 19 '13 at 13:30

Jakob Bowyer

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score 0 · Answer 4 · answered Jul 19 '13 at 13:41

0

Try this:

import os
import sys

try:
    s = os.stat(filename)
    if s.st_size == 0:
        print "The file {} is empty".format(filename)
        sys.exit(1)
except OSError as e:
    print e
    sys.exit(2)

answered Jul 19 '13 at 13:41

Roland Smith

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score 0 · Answer 5 · answered Oct 07 '22 at 16:00

0

Try this:

if file.tell() == 0:
    print("File is empty!")
else: print("File is not empty")

answered Oct 07 '22 at 16:00

NiktW

1

Correct way to check for empty or missing file in Python

5 Answers5