How to check in a bash script if something is running and exit if it is

Question

I have a script that runs every 15 minutes but sometimes if the box is busy it hangs and the next process will start before the first one is finished creating a snowball effect.

Answer 1

I had recently the same question and found from above that kill -0 is best for my case:

echo "Starting process..."
run-process > $OUTPUT &
pid=$!
echo "Process started pid=$pid"
while true; do
    kill -0 $pid 2> /dev/null || { echo "Process exit detected"; break; }
    sleep 1
done
echo "Done."