Systems vary widely in the steps required to fully bring up UNIX and allow users to log in and do their work. This is because UNIX has been ported to many different types of computers and different processors by different computer companies. In the simplest case, you simply turn on the power, and the UNIX system comes up on its own. The system will be ready for use in a few minutes, or it could take much longer depending on firmware diagnostics, restoring network connections, initializing devices and databases, and so on. Other types of UNIX systems will not come up on their own, and you must enter specific commands to bring them up.
Warning: Improper Startup Can Damage the System Severely
On system startup, some UNIX ...