[ Previous | Next | Table of Contents | Index | Library Home | Legal | Search ]

System Management Concepts: Operating System and Devices

Starting the System

When the base operating system starts, the system initiates a complex set of tasks. Under normal conditions, these tasks are performed automatically. For additional information about restarting the system, see:

Booting the System

There are some situations when you want to instruct the system to reboot; for example, to cause the system to recognize newly installed software, to reset peripheral devices, to perform routine maintenance tasks like checking file systems, or to recover from a system hang or crash. For information on these procedures, see:

Creating Boot Images

When the system is first installed, the bosboot command creates a boot image from a RAM (random access memory) disk file system image and the operating system kernel. The boot image is transferred to a particular media such as the hard disk. When the machine is rebooted, the boot image is loaded from the media into memory.

For more information, see "Creating Boot Images" .

Identifying and Changing the System Run Level

The system run level specifies the system state and defines which processes are started. For example, when the system run level is 3, all processes defined to operate at that run level are started. Near the end of the system boot phase of the boot process, the run level is read from the initdefault entry of the /etc/inittab file. The system run level can be changed with the init command. The /etc/inittab file contains a record for each process that defines run levels for that process. When the system boots, the init command reads the /etc/inittab file to determine which processes to start. For information on these procedures, see:

[ Previous | Next | Table of Contents | Index | Library Home | Legal | Search ]