Chapter 5

Video 3: Section 101.2 - Boot the system

- BIOS (Basic Input Output System)
    - Change boot order
- Bootloader
    - LILO (linux loader)
    - GRUB (grand unified bootloader)
        - Specifies what to boot: which drive, kernel etc.
- Show all information about boot and after
    - # dmsg
- Show information about boot only
    - # cat var/log/dmsg
- Init manages all other processes and is the parrent process
- Files that are loaded at boot are located at /boot/
- All the grub files are located at /boot/grub

Video 4: Section 101.3 - Runlevels and Rebooting

- Runlevels
    - 0 = Halt (linux standard)
    - 1 = Single User Mode (recovery) (linux standard)
    - 2 = Debian/ubuntu default
    - 3 = Redhat/SUSE (text mode)
    - 4 = Wildcard
    - 5 = Redhat/SUSE (GUI mode)
    - 6 = Reboot (linux standard)
- Shows configuration file for init (when system boots up)
    - # cat /etc/inittab
- Inside the /etc/init.d folder are scrips which can start or stop programs
- Inside the /etc/rc3.d folder are all the symbolic links that directs to /etc/init.d scripts
    - The scripts in this folder are started when the pc is started with runlevel 3 (rc4.d = runlevel 4 etc)
    - The scrips with K01, are killed
    - The scrips with S01, are started
    - Scrips are loaded on order of number
        - One process depends on the other, you cant kill network before mail or mail will complain
- Shutdown
    - # shutdown {options} {time} {message}
        - [ -k ] = Notify users of a shutdown
        - [ -c ] = Cancel a shutdown
        - [ -r ] = Reboot
        - [ -P ] = Power off
        - {time} = now, 2205, +3 = specify a time for the shutdown (+3= 3 minutes for now
        - {message} = A message for all the users
- Change runlevel
    - # telinit {newrunlevel}
    - # init {newrunlevel}
    - On some systems init cant directly recieve commands

Video 6: Section 102.2 - Install Boot Manager

- LILO bootloader configuration file is in /etc/lilo.conf
- Install LILO
    - # lilo
- GRUB Legacy bootloader configuration file is in /boot/grub/menu.lst
    - default = automatic boot to (0 = 1st, 1 =2nd etc)
    - timeout = time until the default boots
    - LINUX
        - title = Title
        - kernel = kernel location, root= drive uuid, ro = read only, quiet = no feedback, splash = bootlogo
    - Windows
        - title = Titel
        - root = drive where the partition is : (hd1,0) second harddrive, first partition
        - chainloader = loads the windows-boot-loader
- Install GRUB Legacy
    - # grub-install {device}
        - {device} = /dev/sda = The device to install GRUB on
- Do not edit the GRUB2 configuration file but edit the /etc/grub.d of /etc/default.grub
- Backup the MBR
    - # dd if={device} of={backupdirectory}.mbr bs=512 count=1
        - {device} = The device that needs to be backuped
        - {backupdirectory} = T
        - bs = block space (standard 512b)
        - count = number of partitions (mbr is first)
- Restore the MBR
    - # dd if={backupdirectory}.mbr of={device} bs=512 count=1
        - {device} = The device that needs to be restored
        - {backupdirectory} = Directory that contains the *.mbr file/backup file
        - bs = block space (standard 512b)
        - count = number of partitions (mbr is first)
- A superblock contains information about a filesystem

Video 17: Section 103.8 - Basic File editing with "vi"

- Open a file in "vi"
    - # vi FILE.txt
- Change modes (command mode is default)
    - [ ESC ] = Go back to Command mode (read only)
    - [ C ] = Command mode
    - [ I ] = Insert mode (type at selected charcter)
    - [ A ] = Append mode (type behind selected character)
    - [ O ] = Add line below selected character
- Getting around the text
    - [ H ] = Go Left
    - [ J ] = Go Down
    - [ K ] = Go Up
    - [ L ] = Go Right
    - Arrowkeys can be used also
- COMMAND MODE: Cut, Copy and pasting
    - [ Y ] + [ Y ] = Copy the current line in the register (clipboard)
    - [ D ] + [ D ] = Cut the current line and put it in the register
    - [ D ] + [ W ] = Cut the current selected word and put it in the register
    - [ D ] + [ L ] = Cut the current selected character and put it in the register
    - [ P ] = Paste the line/word in the register under/after the current line
- COMMAND MODE: Search
    - [ / ] + {searchterm} = Search in the file and go to the first occurance AFTER the cursor
    - [ ? ] + {searchterm} = Search in the file and go to the first occurance BEFORE the cursor
    - [ N ] = Next occurance
    - [ SHIFT ] + [ N ] = Previous occurance
- COMMAND MODE: Execute
    - [ : ] + "e!" = Revert back to saved file
    - [ : ] + "w" = Save the file
    - [ : ] + "w {newfile}"= Save As another file.
    - [ : ] + "q!" = Exit without saving
    - [ : ] + "wq" = Save and Exit
    - [ Z ] + [ Z ] = Save and Exit
- COMMAND MODE: Change
    - [ C ] + [ W ] = Change the selected word
    - [ C ] + [ L ] = Change the selected character