Linux Cron job rerun script everytime it finish running

view story

http://stackoverflow.com – Hello i have a script that i run that takes about a hour to finish and at the moment i have the script in cron job running 40 7-20 * * * /opt/inventory/run.sh -incremental >/dev/null every hour but sometimes the file doesn't finish in a hour it takes a little over an hour like a hour 5 min sometimes its short sometimes its longer I don't want to allow two instances of the script to be allowed to be running at the same time. Also i want for when a process if its after an hour for it to auto start once it sees the process has terminated. Is this possible? Thank you (HowTos)