Solaris - GUI and CLI mode using dtlogin

Stopping dtlogin
# /etc/init.d/dtlogin stop

Starting dtlogin
# /etc/init.d/dtlogin start

To enable dtlogin type command:
# /usr/dt/bin/dtconfig -e

To disable dtlogin
# /usr/dt/bin/dtconfig -d

To kill dtlogin type command:
# /usr/dt/bin/dtconfig -kill

Read man page of dtlogin for more information.