The runlevel field can define multiple run levels for a process by selecting more than one run level in any combination from 0 through 9. If no run level is specified, the process is assumed to be valid at all run levels. They differ from run levels in that the init command can never enter run level a , b , or c . Also, a request for the execution of any of these processes does not change the current run level. Furthermore, a process started by an a , b , or c command is not killed when the init command changes levels.
Action Tells the init command how to treat the process specified in the process field.
Restart the process when it dies. When the init command enters the run level that matches the entry's run level, start the process and wait for its termination. When it dies, do not restart the process. When the system enters a new run level, and the process is still running from a previous run level change, the program will not be restarted. Start the process, do not wait for its termination, and when it dies, do not restart the process.