Linux Boot Process 5

Question 1

Which file in GRUB2 is used to add custom menu entries that persist across grub2-mkconfig runs?

Accepted Answer

/etc/grub.d/40_custom

Answer

/etc/grub.d/40_custom is designed for user-added menu entries that are preserved when grub.cfg is regenerated.

Question 2

When systemd starts units in parallel, what mechanism does it use to determine dependency order?

Accepted Answer

Unit file directives like After=, Before=, Requires=, and Wants=

Answer

systemd uses dependency directives (After=, Before=, Requires=, Wants=) in unit files to build a dependency graph for ordered parallel startup.

Question 3

What is the significance of PID 1 in the Linux boot process?

Accepted Answer

It is the first user-space process, which becomes the parent of all other processes

Answer

PID 1 is the init process (systemd, SysVinit, etc.) — the first user-space process and ancestor of all other user-space processes.

Question 4

Which boot parameter disables all CPU mitigations for Spectre/Meltdown vulnerabilities, sometimes used for performance testing?

Accepted Answer

mitigations=off

Answer

The mitigations=off kernel parameter is a single flag that disables all CPU vulnerability mitigations (available since Linux 5.2).

Question 5

What is the purpose of the 'quiet' kernel boot parameter?

Accepted Answer

It suppresses most kernel messages from appearing on the console

Answer

The 'quiet' parameter sets the kernel log level low, suppressing verbose boot messages and giving a cleaner console experience.

Linux Practice Test