Solaris shutdown, reboot, init, and halt command differences

In summary, init and shutdown commands cleanly shutdown the system by running the shutdown rc scripts.

The advantage of shutdown is that you can set a shutdown delay and warning message.

halt and reboot are not as clean, no shutdown rc scripts are run so applications will not be brought down clean, I generally do not use these commands unless its a last resort.

init (runs the shutdown scripts in /etc/rc*)
init 0 (shutdown (on sparc it takes it to the ok prompt)
init s (single user mode)
init 5 (shutdown)
init 6 (reboot)

shutdown (runs the shutdown scripts in /etc/rc*, prints message warning users)
shutdown -y -g 0
shutdown -y -i 0 (shutdown to ok prompt)
shutdown -y -i S (single user mode)
shutdown -y -i 5 (shutdown)
shutdown -y -i 6 (reboot)

halt (ungraceful shutdown, use sync;sync;halt)
halt

reboot (ungraceful reboot. Always run sync;sync;reboot. The prefered method is using init.)
reboot (reboot) 
reboot -- -r  (reconfiguration reboot)
reboot -- -s (reboot into single usermode)