• Identify and resolve service failures affecting boot

  • Regain root control of a system

You will have to modify the kernel line during boot time as follows:

Press e to edit the selected grub boot line

Add rd.break to the end of the  line that has linux16 then press CTRL+X to boot the system with the grub information entered

Mount the file system

#mount -o remount,rw /sysroot

#chroot /sysroot

Change the root password

#passwd

Update the selinux labels

#touch /.autorelabel

Restart the system

  • Troubleshoot boot issues

This is dependent of the type of bios that the system is running. You will need to identify  what type of BIOS this system is running.

BIOS - GRUB

If the configuration files are missing run the following commands

#grub2-mkconfig -o /boot/grub2/grub.cfg

or reinstall it on a chroot environment on the right disk

UEFI - EFI

#grub2-mkconfig -o /boot/efi/UEFI/redhat/grub.cfg

  • Identify hardware and hardware problems

There are different commands that can be used to identify the hardware running on the system

To get the CPU information

#lscpu

# dmidecode

To get DISK information

#lsblk

To get ISCSI disk information

# lsscsi

To get PCI devices

#lscpci

To see all the options for each command run the man command.

  • Manage kernel modules and their parameters