How do I determine if standard input is being passed to a Python script?

Question

Some programs hang if they are executed by themselves on the command line such that they are supposed to be receiving input from standard input (i.e., sed "s/test/text/g"). How can a Python script determine if it is being passed data from standard input so an appropriate an error can be raised to avoid hanging for such input?

Answer 1

How about:

import sys
if sys.__stdin__.isatty():
     print('Interactive')
else
     print('Non-Interactive')

Which produces the following output:

C:\>python bobo.py
Interactive

C:\>echo "test" | python bobo.py
Non-Interactive

See also os.isatty()