Let's say you want to add your script or process to UNIX startup, or even you want to be automatically restarted if someone kills it, so here is how you do it:

1. This is done with the help of inittab . So you can check all the current entries via:

lsitab -a

2. Now in order to add your own entry:

vi /etc/inittab

script_name:2:respawn:/usr/sbin/script_name

The respawn option ensures that if someone kills your process, automatically it will be restarted by OS.