The Linux system boots so fast that most of the output scrolls by too quickly to read the text (showing services being started) sent to the console. Therefore observing boot issues/errors becomes a little of a challenge for us.
In this article, we will briefly explain the different stages in a Linux system boot process, then learn how to establish and get to the bottom of boot issues: in terms files to look into or commands to view system boot messages.
Summary Of Linux Boot Process
In summary, once we press the Power On button, the BIOS (Basic Input Output System) a program integrated in a motherboard performs a POST (Power on Self Test) – where hardware such as disks, RAM (Random Access Memory), keyboard, etc are scanned. In case of an error (missing/malfunctioning hardware), it is reported on the screen.
During POST, the BIOS also looks for the boot device, the disk to stat up from (usually the first hard disk, however we may configure it to be a DVD, USB, Network Card etc instead).