Questions and answers

1. System Startup

1.1.

Name all four user-mode processes, one of which the kernel will try to execute as the final step in the boot process.

In the final step in the boot process, the kernel will try to execute one of the following programs as the first user-mode process: /sbin/init, /etc/init, /bin/init and /bin/sh.

First user-mode process

1.2.

The parent of all processes init can be found running in one of eight runlevels. What type of levels are the runlevels 2, 3, 4, and 5?

These runlevels are multi-user runlevels.

Multi-user runlevels

1.3.

What does it mean when the action field in the file /etc/inittab contains the string wait?

The process specified in the fourth field of the same line will be started just once when the specified runlevel is entered and init will wait for its termination.

The file /etc/inittab

1.4.

What type of files do the directories /etc/rc*contain?

These directories contain symbolic links to scripts in /etc/init.d starting with either an S or a K which will call the script with either a start or a stop parameter.

The /etc/init.d/rc script

1.5.

What is the purpose of the Linux Standard Base (LSB) standard?

It ensures that a program compiled in an LSB compatible environment will run on any distribution that supports the LSB standard (within a certain processor architecture).

The LSB standard

1.6.

What is chain-loading?

Chain-loading implies that GRUB will be used to boot the system, and in turn will load and run the proprietary systems bootloader, which then boots the operating system.

GRUB chain-loading

1.7.

What is the purpose of the grub-install command?

The grub-install command is used to install stage 1 to either the MBR or within a partition.

The command grub-install

1.8.

Which command enables you to switch to a different runlevel?

This is done via the telinit command.

The command telinit

1.9.

During boot a filesystem check fails. You read something like fsck failed. Please repair manually followed by CONTROL-D will exit from this shell and continue system startup. How do you proceed?

If you do not press CTRL-D but enter the root password, you will get a shell, in fact /sbin/sulogin is launched, and you should be able to run fsck and fix the problem if the root filesystem is mounted read-only.

When fsck is started but fails

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