1linux init: runlevel for halting the system,0,linux_init
2linux init: runlevel for single user mode,1,linux_init
3linux init: runlevel for multi user mode (traditionally no networking),2,linux_init
4linux init: runlevel for extended multi user mode (networking and services started),3,linux_init
5linux init: runlevel for user defined customization,4,linux_init
6linux init: runlevel for graphical mode,5,linux_init
7linux init: runlevel for reboot,6,linux_init