Actions Available in inittab
respawn Restart the process whenever it terminates. Usually used for getty processes, which monitor for logins.
wait Start the process once when the specified runlevel is entered and wait for its termination before init proceeds.
once Start the process once when the specified runlevel is entered.
initdefault Specifies the runlevel to enter after system boot.
ctrlaltdel Execute the associated process when init receives the SIGINT signal, for example, when someone on the system console presses CTRL-ALT-DEL.