Sync is no longer necessary in any modern version of Unix (Solaris and Linux included). If you're a system administrator, you should learn proper use of the init command, which allows you to change runlevels. Here are a few different uses of init:
# init 6 - reboots the system # init 5 - halts the system (turns power off) # init 0 - sends you to runlevel 0, which is the "ok" prompt (OpenBoot PROM) # init 1 - sends you to single user mode, useful for installing patches.