EOF error when reading from stdin - Python3

Question

I'm receiving the following error when I run this script and press CTR-D to end my input to the program:

The Error:

My-MacBook-Pro-2:python me$ python3 test.py 
>> Traceback (most recent call last):
  File "test.py", line 4, in <module>
    line = input(">> ")
EOFError

The Script

import sys

while(1):
    line = input("Say Something: ")
    print(line)

Why is this happening?

Has anything else changed in test.py vs what you copied and pasted? Because the Traceback as well as the output shows a completely different input command. I cannot replicate this error on my system. (I get KeyboardInterrupt as expected.) — Two-Bit Alchemist
– Two-Bit Alchemist, Commented Oct 10, 2014 at 21:19
Are you sure you're not sending a CTRL+D? That sends an EOF character to stdin, which would explain what you're seeing. — dano
– dano, Commented Oct 10, 2014 at 21:21
@dano I apologize, I mean to type CTRL+D. Yes, essentially my question is how do I handle EOF when reading stdin? — Apollo
– Apollo, Commented Oct 10, 2014 at 21:28

Tammi · Accepted Answer · 2018-10-03 08:21:51Z

This is not likely to help Apollo (besides, question is 4 years old), but this might help someone like myself.

I had this same issue and without hitting a single key, the same code would terminate immediately into EOFError. In my case, culprit was another script executed earlier in the same terminal, which had set stdin into non-blocking mode.

Should the cause be the same, this should help:

flag = fcntl.fcntl(sys.stdin.fileno(), fcntl.F_GETFL)
fcntl.fcntl(sys.stdin.fileno(), fcntl.F_SETFL, flag & ~os.O_NONBLOCK)

I identified the offending Python script and made the correction. Other scripts with input() now work just fine after it.

Edit (plus couple of typos above): This should let you see if STDIN is non-blocking mode:

import os
import sys
import fcntl
flag = fcntl.fcntl(sys.stdin.fileno(), fcntl.F_GETFL)
print(
    "STDIN is in {} mode"
    .format(
        ("blocking", "non-blocking")[
            int(flag & os.O_NONBLOCK == os.O_NONBLOCK)
        ]
    )
)

dano · Accepted Answer · 2014-10-10 22:07:27Z

1

When you use input, there's no need to send EOF to end your input; just press enter. input is designed to read until a newline character is sent.

If you're looking for a way to break out of the while loop, you could use CTRL+D, and just catch the EOFError:

try:
    while(1):
        line = input("Say Something: ")
        print(line)
except EOFError:
    pass

answered Oct 10, 2014 at 22:07

dano

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