How do I restart UNIX server or workstation?

You can use the following procedure to restart a UNIX system.

Login as root user. If you are not root use, use su or sudo command as follows:
su -
OR
sudo -i

Once logged in as root, type the reboot command to reboot the system:
# reboot
You can also use the shutdown command as follows:
# shutdown -r now
If you are using Solaris UNIX, try the following command:
# shutdown -y -i6 -g0
Where,

• -y : Do not prompt for any questions.
• -i6 : Indicates init level 6 which is nothing but reboot.
• -g0: Grace period, the default is 60 seconds. To reboot immediately set it to zero (0).