Conceptual understanding needed for LPIC
Dynamically generated at startup.
running process appear as folder in /proc/
/dev$ ls -hal (...) crw-rw---- 1 root dialout 4, 89 Dec 2 19:51 ttyS25 brw-rw---- 1 root disk 8, 0 Dec 2 19:51 sda brw-rw---- 1 root disk 1, 14 Dec 2 19:51 ram14 (...)
Note: The boot order (ressource the computer will boot on) is definted in the BIOS.
GRUB = GNU GRand Unified Bootloader ( https://en.wikipedia.org/wiki/GNU_GRUB ) LILO = LInux LOder ( https://en.wikipedia.org/wiki/LILO_%28boot_loader%29 )
Both are now covered in LPIC1 ! GRUB Legacy and GRUB2 use different configuration file.
GRUB is typically installed on a harddrive (but can also be on CR-ROM, USB, network drive).
GRUB display list of OS. Including sometimes more than one kernel version. It can include additional entries (recovery mode, memory test…)
To determine Grub version: $ grub-install -v
How to access GRUB?: Hold shift key on startup or ESC at timer
LILO is not covered in LPIC 1 anymore
LILO is hardly used anymore
The bootloader is written on the Master Boot Record. The BIOS looks at a specific area of the harddrive to load the bootloader.
MBR is being replace with the GUID Partition Table.
There are many options that can be passed to the kernel by the bootloader. The most essential one are:
The harddrive on which the OS is present
Where the linux kernel is located
An initial ram disk that contain kernel module and tools necessary to boot
The system load both vmlinux and initrd in memory and then start the kernel
Other boot options
Changing boot options at boot time is non-persistent
dmesg refers to the kernel message
The log file /var/log/dmesg show the kernel message up to when the system finished booting (log prompt).
Contain kernel message and additional message from other deamon.
/!\ Not present in latest ubuntu (12.10), has been replaced by /var/log/syslog
Process that starts all other process. (parent process)
Being replaced with upstart / systemd.