CODEWITHSUNDEEP
pythonpython-2.7stdin
mathsaey
mathsaey

Reputation: 78

Using raw_input after using fileinput

I have a python script that can read it's data from stdin or from a file. In order to do this, I use fileinput in the following manner:

for line in fileinput.input(args.path):
    read.parseLine(line)

Which works fine. However, after reading this file/input, I want to be able to ask the user for some additional input through stdin using read:

data = raw_input("Please enter your data for port {}: ".format(core.getPort()))

This does not work, since raw_input keeps on encountering an EOF.

Please enter your data for port 0: Traceback (most recent call last):
    File "app_main.py", line 72, in run_toplevel
    File "/usr/local/bin/dvm", line 98, in <module>
    data = raw_input("Please enter your data for port {}: ".format(core.getPort()))
EOFError

I tried to resolve this by usingsys.stdin.seek(0) But that returns the following error:

Traceback (most recent call last):
    File "app_main.py", line 72, in run_toplevel
    File "/usr/local/bin/dvm", line 88, in <module>
    sys.stdin.seek(0)
IOError: [Errno 29] Illegal seek: '<fdopen>'

Is there any way to ask for user input after using fileinput?

Upvotes: 1

Views: 282

Answers (1)

Martijn Pieters
Martijn Pieters

Reputation: 1123590

fileinput doesn't do anything to sys.stdin other than read (it explicitly makes sure not to close sys.stdin).

But you cannot use sys.stdin both as file input and for raw_input(); either sys.stdin is attached to a pipe, or it is connected to the user terminal. It cannot be attached to both. And fileinput would read from stdin indefinitely unless an end-of-file was reached at some point.

In other words, you cannot use raw_input when sys.stdin is not attached to a terminal. You could use the os.isatty() function to detect if a terminal is available:

if os.isatty(sys.stdin.fileno()):
    # we have a terminal, I can use `raw_input()`

Upvotes: 2

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