From the terminal verify if python 3 is installed

Question

I am writing a shell script, and before the script runs I want to verify that the user has Python 3 installed. Does anyone know or have any ideas of how I could check that, and the output be a boolean value?

Answer 1

Interactive shell

Simply run python3 --version. You should get some output like Python 3.8.1 if Python 3 is installed.

Shell script

You can use the command or type builtins:

command -v python3 >/dev/null 2>&1 && echo Python 3 is installed  # POSIX-compliant type -P python3 >/dev/null 2>&1 && echo Python 3 is installed     # Bash only 

Using which is not recommended as it requires launching an external process and might give you incorrect output in some cases.