Grub

Resources

• http://www.gnu.org/software/grub/
• https://en.wikipedia.org/wiki/GNU_GRUB
• https://help.ubuntu.com/community/Grub2
• https://wiki.gentoo.org/wiki/GRUB2
• https://www.dedoimedo.com/computers/grub-2.html
• Linux Jargon Buster: What is Grub in Linux? What is it Used for?

Repair/update Grub2

• Repair Grub2
• How to Update Grub on Ubuntu and Other Linux Distributions. Good instruction. Two disks; each with its own Linux distribution. The second disk won't install Grub. So the Linux on the 1st disk needs to update its grub so it can see the Linux on the 2nd disk.
• GRUB Rescue | Repairing GRUB (arch linux) Apr 2019

Ubuntu: Boot Repair

https://help.ubuntu.com/community/Boot-Repair from a live USB

Not see Grub after re-install/upgrade Windows

Fix Grub Not Showing For Windows 10 Linux Dual Boot

Not see Windows in Grub menu

sudo apt install os-prober

echo 'GRUB_DISABLE_OS_PROBER=false' | sudo tee -a /etc/default/grub

sudo os-prober
sudo update-grub

Add a new entry to boot an ISO

• UBUNTU Using GRUB2 to boot to ISO (kind of outdated)
• Custom Grub Boot Menu Feb 2019

Pop_OS! does not use Grub, but rather systemd-boot

How to install grub menu on pop os?

Configuration - /etc/default/grub

How to Configure the GRUB2 Boot Loader’s Settings

Configuration options:

• Scripts in /etc/grub.d
• Configuration file at /etc/default/grub

Incorporating changes:

• grub2-mkconfig (or grub-mkconfig for Grub v1) reads configurations and generates a new configuration for /boot/grub2 (or /boot/grub)

Show the grub2 screen

To show the grub2 screen, run sudo nano /etc/default/grub and comment out the line GRUB_HIDDEN_TIMEOUT=0 and change the line GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" to GRUB_CMDLINE_LINUX_DEFAULT="". Remember to run 'sudo update-grub' after any change to grub.

Change theme

How To Change GRUB Theme In Linux

Set Screen Resolution

Set Screen Resolution using Kernel Boot Parameter on Linux. I try "vga=ask" and "vga=341" and both do not work.

How do I set the grub timeout and the grub default boot entry?

https://askubuntu.com/questions/148095/how-do-i-set-the-grub-timeout-and-the-grub-default-boot-entry

1. gksudo gedit /etc/default/grub
2. Change as you like. Save and closed the file.
   • You can change the default from 0 to any number
   • You can change the "hidden timeout" (no menu)
   • You can force the grub menu to show by commenting out the two GRUB_HIDDEN lines with a # at the beginning of the line
   • set the grub menu timeout (default is 10 seconds)
3. sudo update-grub
4. Reboot

Grub Customizer - GUI program

• How To Change The GRUB Boot Order Or Default Boot Entry In Ubuntu, Linux Mint, Debian, Or Fedora With Grub Customizer
• How to Edit GRUB with GRUB Customizer
• Add a live ISO boot to GRUB menu

Add a splash image

Follow the instruction at https://help.ubuntu.com/community/Grub2/Displays. Note that Grub2 will search the image based on some priority and there are also some minor requirements on the images. To test

sudo apt-get install grub2-splashimages
sudo cp /usr/share/images/grub/Moraine_Lake_17092005.tga /boot/grub/
sudo update-grub

Boot into command line

http://www.linuxandubuntu.com/home/how-to-boot-into-linux-command-line

1. Highlight the first item (default) and press 'e' in the GRUB menu
2. Navigate to the line that starts with ‘linux’, change the runlevel to 3 (at the end of the line). Level 3 means multi-user, command-line only system
3. Press Ctrl+x or F10 to boot into

To switch back to GUI, type sudo init 5. Level 5 is the default.

Dual boot

How to setup a Windows 10, Linux Mint 19.1 Dual Boot with Encrypted Partitions on a Dell XPS 15 9560

Triple boot

• Complete Guide To Triple Boot Windows, Lubuntu And Debian
• Adding Batocera on dual boot. Essentially, I had to install each while only their drive was in the computer. I did Xubuntu last, then added the other two drives and did a bunch of fiddling with Grub for it to pick up the OS's.

Where is grub installed

• Where is grub installed and do I need a new one for a separate linux installation?
• https://askubuntu.com/a/30347 which suggests Boot info script. Very useful. We can run it using live USB.
  • The boot files in each partition will be discovered.
  • After running sudo ./bootinfoscript, the result is saved in a text file "RESULTS.TXT".
  • On my system it shows Grub2 is installed in the MBR of /dev/sda. My setup is /dev/sda for Windows 10, /dev/sdb for a backup disk and /dev/sdc for Ubuntu.
  • The RESULTS.txt shows /sdc/boot/grub/grub.cfg contains the boot menu I saw when the system boots up.
• https://help.ubuntu.com/community/Boot-Repair

MBR and GPT

• MBR
  • https://en.wikipedia.org/wiki/Master_boot_record
  • MBR
  • MBR only supports up to 4 primary partitions. If you want more, you have to make one of your primary partitions an extended partition and create logical partitions inside it. Cf. GPT also allows for a nearly unlimited number of partitions.
• What's the Difference Between GPT and MBR When Partitioning a Drive?
• How to Check if a Disk Uses GPT or MBR, and Convert Between the Two (Windows)
  • On Linux, type sudo fdisk -l. The Disklabel type will show the type (e.g. dos, gpt, ...).
• Fdisk Command in Linux (Create Disk Partitions)
• How to Convert MBR to GPT Without Losing Data in Windows
• slax Linux asks your disk uses msdos partition scheme (use MBR, not GPT).

Share files between OSes

Create a completely separate partition using a suitable filesystem, such as NTFS that both can read.

Run Live Linux on Ram Disk

• How to Get to the GRUB menu at boot time & change the GRUB menu timeout at boot?
• Can I boot a Live USB fully to RAM, allowing me to remove the disk? (tested on Ubuntu 20.04)
  1. F11 - boot from USB on my old PC
  2. Hold Shift (or ESC on UEFI boot) in order to show GRUB menu
  3. Select English, Enter
  4. F6, followed by ESC to close the little popup
  5. Using the arrow key to add 'toram' (no quotes) after 'quiet splash'.
  6. Press Enter. You will see the LED on USB drive flashes. It took 7 minutes on my USB 2 port to enter the XFCE Desktop.
  7. Eject & unplug the USB drive.

Increase root partition in Live session

• For Ubuntu/Mint, the "toram" option in boot can get about 3.9GB root partition. So I cannot test the "dd" command to back up a DVD disk since it requires more than 3.9GB space for the final iso file.
• How to adjust the size of the root partition on live Arch Linux system?
• How To Adjust The Size Of The Root Partition On Live Arch Linux. When you boot the Arch Linux livecd, press e or hit tab key to edit the kernel parameters. Go to the end of the line that says ".... linux=... initrd=...." something like that and append cow_spacesize=1G at the end to get 1GB size root partition or whatever space left from RAM. It seems that cow_spacesize is specific to Arch Linux and its derivatives.

Systemd

• Analyze Linux startup performance
• Systemd Deep-Dive: A Complete, Easy to Understand Guide for Everyone (video)
• Linux has nearly half of the desktop OS Linux market. ChromeOS doesn't have systemd. It has upstart, which was one of the most widespread init systems.

Legacy BIOS

Fedora 37 Looks To Deprecate Legacy BIOS Support

BIOS, CMOS, UEFI, AHCI

• BIOS, CMOS, UEFI - What's the difference? (video)

AHCI vs RAID

• Installing Linux alongside Windows is usually fairly painless – for many installs, you don’t need to disable Secure Boot now as most distros are signed. However, sometimes, the installer runs but you can’t see your hard disk. This can be resolved by switching the hard disk mode from RAID to AHCI – provided you aren’t specifically using RAID features, this should cause no ill effects. You will need to give Windows a heads-up or you’ll get a blue screen!
• Dual boot - Preparation

Accessed remotely while it's off

Can Your Computer Be Accessed Remotely While It’s Off?

Bootable DOS USB Drive for BIOS update

How to Create a Bootable DOS USB Drive

Dell Optiplex

• How To Fix A Dell With A No Bootable Device Or No Boot Device Found Problem
• How To Fix Dell Computer Hard Drive Not Detected / Hard Drive Not Found / Hard Drive Not Installed
• To have a one-time boot up. Hit F12
• In my case, I don't need to upgrade BIOS (mine is 1.18 from 2019). I've used USB to install Ubuntu 22.04 on my SSD. However I cannot boot into it.
  • Hit F2 to go to BIOS.
  • Boot Sequence: Check ubuntu. Boot List Option: UEFI
  • Advanced Boot Options: Checked both options.
  • System Configuration: SATA Operation - AHCI.
  • Security Boot: Uncheck 'Secure Boot Enable'