Resources

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

Not see Grub after re-install/upgrade Windows

Fix Grub Not Showing For Windows 10 Linux Dual Boot

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UBUNTU Using GRUB2 to boot to ISO (kind of outdated)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

gksudo gedit /etc/default/grub
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)
sudo update-grub
Reboot

Grub Customizer - GUI program

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

Highlight the first item (default) and press 'e' in the GRUB menu
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
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

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
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

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.

Systemd

Analyze Linux startup performance

Legacy BIOS

Fedora 37 Looks To Deprecate Legacy BIOS Support

Bootable DOS USB Drive

How to Create a Bootable DOS USB Drive

Grub

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