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

You can use this function to detect if the input is from a pipeline or not.

sys.stdin.isatty()

It returns false if the input is from pipeline or true otherwise.