14.1 Boot Issues

When an error occurs during boot, the Linux VM will boot into a panic mode. To fix this, we need to boot into single user mode to regain control and repair the problem.

Single user mode is reached by rebooting your machine and in the Kernel selection changing the kernel entry to boot into single user mode.

Single user mode

Imagine: you had a new admin in your team, but it was decided that it would be in everybody’s best interest if Nietzche pursued a different career.

Now that your staffing issue has been solved, there are a couple of remaining issues. One of them is a machine that has been “fixed” by this admin.

Go to the console of your server; you should see a message during the boot crash.

You can give the machine it’s root password greater to continue, we can check the boot log in journalctl or for example by reading the file /var/log/boot.log

cat /var/log/boot.log

Read it carefully to understand what is wrong, when you have an idea what is wrong, trigger a reboot.
There is a button at the top right.

At the following screen use the keyboard arrow keys to move up and down to stop the timer:

Go to the top kernel and press the e button.

Go to the line that begins with linux ($root)

Go to the end of this line and add rd.break

It should now look something like this:

Press ctrl-x to start the boot process with this kernel and therefor into single user mode.

During boot the real root file system will be mounted under /sysroot but the mount is in read-only so we cannot change anything.

To change the /sysroot to read-write we must remount it:

Mount -o remount,rw /sysroot

Can you find the problem?

Check the /sysroot/etc/fstab file.

Remove the broken entry.

Reboot your system by typing exit until the system reboots.

Check if it boots normaly.