RHCSA Exam Study Guide with Complete Solutions
commands/process to reset root password - Answer️️ -on boot:
select most recent kernel
`e` to edit
goto line with linux16, add `` to end of line
`ctrl+x` to continue boot to rd rescue mode
remount /sysroot as readable (defaults to read only i...
add `systemd.unit=rescue.target` to the end of the linux16 line
regenerate grub config with the following command:
`grub2-mkconfig -o /boot/grub2/grub.cfg`
To diagnose boot issues more easily, you decide to disable 'quiet boot' and
'graphical boot' by removing 'quiet' and 'rhgb' from the kernel boot
parameters. How would you accomplish this so it's persistent? -
Answer✔️✔️-Edit the 'GRUB_CMDLINE_LINUX' line in
'/etc/default/grub' then regenerate the bootloader config using 'grub2-
mkconfig -o /boot/grub2/grub.cfg'.
Under normal circumstances, what is systemd's PID (Process ID)? -
Answer✔️✔️-PID 1 - because it's the very first binary called by the kernel at
boot, and is responsible for starting up all other processes.
Which rescue parameter would you pass to the kernel from the grub2
menu if your system was failing to boot because a filesystem check was
failing? - Answer✔️✔️-systemd.unit=emergency.target
Booting to the emergency target state drops to a rescue shell after the 'root'
filesystem has been mounted readonly, but BEFORE other FS checks are
carried out. Although you could do the same with 'rd.break' it would
require considerably more effort.
You are a member of a team of admins who are responsible for a critical
system. This system has two different web servers installed: The first
(Nginx) is used to serve content, the other (httpd) is installed only to satisfy
dependencies and should never be started as it causes a conflict. What
command could you run to ensure that 'httpd' is never accidentally started
or enabled by another admin? - Answer✔️✔️-systemctl mask httpd
You're having a bad day and accidentally delete the 'initramfs' file in /boot
that matches your current kernel. Which command would you run to
recover from this? - Answer✔️✔️-dracut
You've just made a configuration change to the 'SSHD' service and want to
daemon to reload it's configuration without disconnecting anyone. How
could you accomplish this? - Answer✔️✔️-systemctl reload sshd.service
persistent hostname change with systemd - Answer✔️✔️-hostnamectl set-
hostname your.host.name
command to show open/listening ports - Answer✔️✔️-ss -taupen
t = tcp
a = all types of connections (sending as well as listening)
u = udp
p = process ids (and information about the processes that are holding those
ports
e = extra information
n = numbers only (don't resolve the hostnames)
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