I want to create cron job that runs a script every 5 seconds. Seeing that cron jobs only allows increments of minutes 0-59 and so on.
I thought to create another scr
Try using anacron or, better yet, an init script to start when the computer starts.
If you want the script to "restart itself", you'll need to run something every few minutes to check the original is still running. This can be done in inittab (/etc/inittab) or, on Ubuntu, /etc/event.d. Try man 5 inittab, looking at the 'respawn' option.