Display a small progress spinner in bash while running your commands with optional message.

This can be used for anything that takes time.

This example passes a static string to start_spinner which remains in place until stop_spinner is called.

source spinner.sh

start_spinner "This is my cool spinner message"
sleep 10

stop_spinner

This example passes a command to start_spinner_eval which will be re-evaluated each time the spinner is drawn until stop_spinner is called.

source spinner.sh

start_spinner_eval 'cat log | tail -1'

for i in {1..10}; do
    echo "Iteration number ${i}" >> log
    sleep 1
done

stop_spinner

You can set an environment value called SPINNER_DELAY to change the default (0.25 seconds) delay used when drawing the spinner.