Chpt 3: How Linux Boots

Question 1

Расскажи вообще, как Linux грузится?

Answer 1

1. A boot loader finds the kernel image on the disk, loads it into memory, and starts it.
2. The kernel initializes the devices and its drivers.
3. The kernel mounts the root filesystem.
4. The kernel starts a program called init.
5. init sets the rest of the processes in motion.
6. The last processes that init starts as part of the boot sequence allow you to log in

Question 2

How many runlevels Linux system has and how it works on them?

Answer 2

There are a few different variations, but most Linux distributions use the System V style discussed here.
Some distributions use a simpler version that resembles the BSD init, but you are unlikely to encounter
this.
3.1.1 Runlevels
At any given time on a Linux system, a certain base set of processes are running. This state of the
machine is called its runlevel, and it is denoted with a number from 0 through 6. The system spends most
of its time in a single runlevel. However, when you shut the machine down, init switches to a different
runlevel in order to terminate the system services in an orderly fashion and to tell the kernel to stop. Yet
another runlevel is for single-user mode.

Question 3

What is init process (/sbin/init)?

Answer 3

There is nothing special about init. It is a program just like any other on the Linux system, and you’ll find
it in /sbin along with other system binaries. The main purpose of init is to start and stop other programs
in a particular sequence.

Question 4

What is init configuration file?

Answer 4

/etc/inittab.

Question 5

Where are rc scripts located?

Answer 5

/etc/rc.d/rc[runlevel number].d

Question 6

What are files in /etc/rc.d?

Answer 6

Actually symlinks to files in /etc/init.d

Question 7

stopped at: 3.1.4 Controlling init

Answer 7

f