To change the runlevel for a system without rebooting or changing the /etc/inittab

$ sudo telinit 0   halt

$ sudo telinit 1   single-user mode

$ sudo telinit 2   Not used (user-definable)

$ sudo telinit 3   Full multi-user mode

$ sudo telinit 4   Not used (user-definable)

$ sudo telinit 5   Full multi-user mode (with an X-based login screen)

$ sudo telinit 6   Reboot

$ sudo telinit q   Reload daemon configuration equivalent systemctl daemon-reload

regards,

T.Dhanasekar