Bash:Variables

Bash is a *nix shell

To check within a startup script (like .bashrc) whether or not Bash is running interactively. Test if $- has an 'i' in it or if $PS1 (the prompt) exists.

case "$-" in
*i*)	echo This shell is interactive ;;
*)	echo This shell is not interactive ;;
esac

if [ -z "$PS1" ]; then
        echo This shell is not interactive
else
        echo This shell is interactive