0                                                                            
       Shut the machine down so it is safe to remove the power.              
       Have the machine remove power if it can. This state can be            
       executed only from the console.                                       
       Note that init 0 should not be used if you have a USB                 
       keyboard attached to the console. During an init 0, the               
       USB stack gets shut down and the system then waits for a              
       keyboard keypress interrupt before rebooting. Since USB is            
       gone, there's no way for a keypress on the USB keyboard to            
       get serviced, and the system does not respond. If this                
       occurs, you must either press the hardware reset button or            
       power cycle the system.                                               
1                                                                            
       Put the system in single-user mode. Unmount all file                  
       systems except the root filesystem. All user processes are            
       killed except those connected to the console. It is                   
       recommended that this state be executed only from the                 
       console.                                                              
2                                                                            
       Put the system in multiuser mode. All multiuser                       
       environment terminal processes and daemons are spawned.               
   5                                                                            
          Stop the UNIX system and go to the firmware monitor.                  
   6                                                                            
          Stop the UNIX system and reboot to the run-level defined              
          by the initdefault entry in /etc/inittab.