How do I check if I am in a graphical environment on a Mac using bash?

Question

I am trying to determine whether or not I am in a graphical environment via bash on a Mac.

The goal is to have an if/else structure within a bash script that can handle these two cases.

Case 1: I can open windows from the command-line.

Case 2: I cannot open windows from the command-line.

Answer 1

Assuming it's enough to check whether Finder is running, you may use

if pgrep -qx Finder; then
    echo 'Finder is running'
else
    echo 'Finder is not running'
fi

If you are running some X server (not commonly the case on macOS), and want to check whether the current session is attached to it,

if [ -n "$DISPLAY" ]; then
    echo 'In X'
else
    echo 'Not in X'
fi

Both of these tests are quite naive but would at least cover the most basic situations.