How to Accept Command Line Arguments With Python Using <

Question

Is it possible to run a python script and feed in a file as an argument using <? For example, my script works as intended using the following command python scriptname.py input.txt and the following code stuffFile = open(sys.argv[1], 'r').

However, what I'm looking to do, if possible, is use this command line syntax: python scriptname.py < input.txt. Right now, running that command gives me only one argument, so I likely have to adjust my code in my script, but am not sure exactly how.

I have an automated system processing this command, so it needs to be exact. If that's possible with a Python script, I'd greatly appreciate some help!

Answer 1

< file is handled by the shell: the file doesn't get passed as an argument. Instead it becomes the standard input of your program, i.e., sys.stdin.

Answer 2

You can use the sys module's stdin attribute as a file like object.

Answer 3

When you use the < operator in a shell you are actually opening the file and adding its contents to your scripts stdin However there is is a python module that can do both. It's called fileinput. https://docs.python.org/2/library/fileinput.html It was shown in this post How do you read from stdin in Python?