Shut Down a Solaris UNIX System

How do I shutdown a Solaris UNIX machine or server using command prompt?

You need to use the shutdown command as follows (you must login as root):
# shutdown -y -g0 -i S
The following command will scheduled a shutdown in 180 seconds and will display message "Memory upgrade, save all data " to all logged in members:

shutdown -i S -g 180 "***  Memory upgrade, save all data ***"

The shutdown command can be aborted before completing 180 seconds counter.

poweroff Command

You can also use the poweroff command its is equivalent init 5:
# poweroff
OR
# init 5