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Am I in a Terminal?

Leonora Tindall 2016/09/13

Sometimes, it can be useful to know if your program is running in a terminal. Since Python 3.3, this functionality has been available in the os module:

#!/usr/bin/env python3

# Test if this Python script is running in a terminal or not.

import os

    size = os.get_terminal_size()
    print("I am in a terminal of size {}x{}"
        .format(size[0], size[1]))
except OSError:
    print("I am not in a terminal.")

Here is an example of it in operation:

$ ./ 
I am in a terminal of size 80x24

$ ./ | tee
I am not in a terminal.

This is useful for many reasons. For example, scripts which have interactive “beautifications” like progress bars, no-freeze spinners, and animations should cease these antics when piped into the input of other programs or redirected to files. Additionally, programs being run from scripts can disable all performance-impacting interactivity, including interactive KeyboardInterrupt handling; if a user Ctrl+Cs a script, they want it to stop, immediately, not ask to quit.