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

Use this script:

FILE="/tmp/my_file"
if [ -f "$FILE" ]; then
   echo "Still running"
   exit
fi
trap EXIT "rm -f $FILE"
touch $FILE

...script here...

This script will create a file and remove it on exit.