How to read from stdin or from a file if no data is piped in Python?

Question

I have a CLI script and want it to read data from a file. It should be able to read it in two ways :

• cat data.txt | ./my_script.py
• ./my

Answer 1

I'm a noob, so this might not be a good answer, but I'm trying to do the same thing (allow one or more files on the command line, default to STDIN otherwise).

The final combo I put together:

parser = argparse.ArgumentParser()
parser.add_argument("infiles", nargs="*")
args = parser.parse_args()

for line in fileinput.input(args.infiles):
    process(line)

This seems like the only way to get all the desired behavior in one elegant package, without requiring named args. Just like unix commands are used as such:

cat file1 file2
wc -l < file1

Not:

cat --file file1 --file file2

Would appreciate feedback/confirmation from veteran idiomatic Pythonistas to make sure I've got the best answer. Haven't seen this complete solution mentioned anywhere else, just fragments.