Linux Boot and Shutdown 29 init will wait until the script has finished before running any other scripts. Other options include respawn, which will restart the process if it dies or stops (for getty), and once, meaning that the process should be run only once and never again. The fourth field lists the script or process to run. You can see how these scripts work below. What's a Runlevel? The runlevel of a machine determines what functionality the system should be providing. Just as Windows 98 provides a safe mode, UNIX has a single-user safe mode, plus other configurations available: Runlevel 0 1 2 3 4 5 6 Functionality Halt Single-user mode Multiuser, no NFS Multiuser, with NFS Unused X11 console (xdm, gdm, or kdm) a Reboot a In Solaris 2.x, runlevel 5 will power down the system. It won't do that in Linux. Two of these runlevels are really for stopping or rebooting the machine. Runlevel 1 allows only root to log in, and only the root partition is mounted. This is primarily for emergency situations where one of the other partitions is corrupted. The default runlevel for Red Hat is 3, which is a typical