Silence is golden

$ touch .hushlogin

Disable Solaris GUI

It could be done by using one of the two methods.
The first one does its job immediate.

# svcadm disable cde-login

(You could also use the full FMRI, svc:/application/graphical-login/cde-login:default)

The second one takes place during the next startup.

# /usr/dt/bin/dtconfig -d

(Use -e switch to enable auto-start)