Ubuntu Custom Boot ISO with Grub.d

If you're a programmer looking to create a custom boot ISO for Ubuntu, then Grub.d is a helpful tool you can use. Grub.d is a module for the Grub bootloader that allows you to customize your boot menu, giving you greater flexibility and control over your system's boot process.

What is Grub.d?

Grub.d is a collection of shell scripts that you can use to create custom menu entries in the Grub bootloader. With Grub.d, you can add your own boot entries, customize existing entries, and apply changes to the Grub configuration file.

Why Use Grub.d?

Grub.d can be a powerful tool for programmers looking to customize their Ubuntu boot process. Some benefits of using Grub.d include:

• Flexibility: Grub.d allows you to add your own custom menu entries, giving you greater control over your boot process.
• Simplified configuration: By using Grub.d, you can organize and simplify your boot configuration file.
• Security: Grub.d can help you protect your system by allowing you to create boot entries that require authentication.

How to Use Grub.d

To get started, you'll first need to install the Grub.d module. You can do this using the following command:

sudo apt-get install grub2-common

Once you've installed Grub.d, you can start customizing your boot configuration file. This file is located at /etc/grub.d/. Within this directory, you'll find a number of pre-existing shell scripts that generate menu entries for Grub.

To create a custom menu item, you'll need to create a new shell script in this directory. The script should start with a two-digit number to indicate the order in which the entry will appear in the Grub menu.

For example, if you want to create a custom menu item called "My Boot Entry", you could create a script file with the name "10_mybootentry". Within this script, you can add the commands needed to create your boot entry.

Here's an example of what the script might look like:

#!/bin/sh
exec tail -n +3 $0
# This script creates a custom boot entry called "My Boot Entry"

cat << EOF
menuentry "My Boot Entry" {
        insmod part_gpt
        insmod ext2
        set root=(hd0,gpt1)
        linux /boot/vmlinuz-3.13.0-24-generic root=UUID=204bfb0e-ea53-40f2-b52e-9b9d3c70d1d3 ro quiet splash
        initrd /boot/initrd.img-3.13.0-24-generic
}
EOF

This script adds a new menu item called "My Boot Entry" to Grub. It specifies the root partition, kernel image, and initial RAM disk needed to boot the system.

Once you've created your script, you'll need to make it executable by running the following:

sudo chmod +x 10_mybootentry

Finally, run the following command to regenerate the Grub configuration file:

sudo update-grub

Your new boot menu item should now be available when you reboot your system.

Conclusion

Grub.d can be a powerful tool for customizing your Ubuntu boot process. With a little bit of shell scripting knowledge, you can create custom boot entries that give you greater control and flexibility over your system. Plus, using Grub.d can help you organize and simplify your boot configuration file, making it easier to manage in the long run.