How to flush output of print function?

Question

How do I force Python's print function to output to the screen?

_{This is not a duplicate of Disable output buffering - the linked question is attempting unbuffered output, while this is more general. The top answers in that question are too powerful or involved for this one (they're not good answers for this), and this question can be found on Google by a relative newbie.}

Answer 1

Also as suggested in this blog one can reopen sys.stdout in unbuffered mode:

sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)

Each stdout.write and print operation will be automatically flushed afterwards.

Answer 2

I did it like this in Python 3.4:

'''To write to screen in real-time'''
message = lambda x: print(x, flush=True, end="")
message('I am flushing out now...')

Answer 3

Loved Dan's solution! For python3 do:

import io,sys
class flushfile:
    def __init__(self, f):
        self.f = f
    def write(self, x):
        self.f.write(x)
        self.f.flush()
sys.stdout = flushfile(sys.stdout)

Answer 4

Running python -h, I see a command line option:

-u : unbuffered binary stdout and stderr; also PYTHONUNBUFFERED=x see man page for details on internal buffering relating to '-u'

Here is the relevant doc.

Answer 5

With Python 3.x the print() function has been extended:

print(*objects, sep=' ', end='\n', file=sys.stdout, flush=False)

So, you can just do:

print("Visiting toilet", flush=True)

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Python Docs Entry

Answer 6

Why not try using an unbuffered file?

f = open('xyz.log', 'a', 0)

OR

sys.stdout = open('out.log', 'a', 0)