-bash-3.1# shutdown -rn now
Connection to localhost closed by remote host.
Connection to localhost closed.
Sometimes I work with embedded systems/custom kernels without any of the fancy init scripts and other common Linux basics that most would expect. This means that often the "reboot" command (which uses an init script) will never work, not only that but it will hang the server and a manual power cycle or reboot will be necessary.
The above command forces it to reboot and works even without an init script, but be warned that it won't unmount anything so make sure the system is truly ready and safe to be rebooted.