Create a multiboot USB drive with GRUB in Linux

Linux live USB drives are one of the most useful tool that every Linux user should keep handy. They are life saver in case of  system crash and configuration mess up.

This tutorial will help you to put multiple Linux live ISO files inside a singe bootable USB drive very easily, without any mess.

requirements:

• One USB pendrive, 4 GB or more recommended.
• Linux live CD distribution or Linux installer ISO files.
• A machine running a Linux distribution of your choice.

1. Format the USB drive

Before continue, take backup of all important data of that USB drive and make sure that this is the drive to format.

Now format the drive with a single FAT32 partition, with software of your choice like Gparted or mkfs .

Here's how to format the drive with the mkfs command.

sudo mkfs.vfat -F 32 -n your_drive_name /dev/sdc1

make sure that which drive and partition you want to format, in this case it was /dev/sdc1 and change your_drive_name with any name of your choice. Or use Gparted, there is lesser amount of risk involved with it.

2. mount partition and create folders

After formating, mount the partition to a easily accessible folder with read write permission and create required folders.

mkdir ~/multiboot

sudo mount /dev/sdc1 ~/multiboot/

cd ~/multiboot/

mkdir boot

mkdir iso_boot

The boot directory to store GRUB bootloader related files and iso_boot directory to store Linux installer ISO files.

3. Install GRUB on the USB drive

Now install the GRUB bootloader on the USB drive. Depending your your system, GRUB could be either x86_64-efi or i386-pc, but here we are going the use the i386-pc platform.

sudo grub-install /dev/sdc --target=i386-pc --boot-directory=~/multiboot/boot/ --force

note: Use only /dev/sdc not /dev/sdc1 , wait for some time, this process may return some error message but it's fine.

4. toggle the USB drive bootable flag

If the the drive is not already bootable, toggle the boot flag with parted , cfdisk or fdisk .

One line parted command to toggle boot flag.

sudo parted /dev/sdc toggle 1 boot

With cfdisk , just run the command and follow the interactive cfdik CLI interface and watch the * mark.

sudo cfdisk /dev/sdc

5. Copy ISO files

Now copy the ISO files of various distributions like Ubuntu, Debian, Linux Mint etc. to the ~/multiboot/iso_boot folder. Use a file manager like Nautilus , Dolphin, etc. or do it with the cp command.

6. Create the grub.cfg file

Everything is almost ready, now just create the grub configuration file to make the ISO files available to boot from USB drive. Create a text file with a text editor of your choice inside the ~/multiboot/boot/grub/ folder. Then put the text bellow.

# Multiboot USB drive GRUB configuration file

#  By:~    https://www.pcsuggest.com

set timeout=10
set default=0
insmod loopback

menuentry "lubuntu 14.04.1 32 bit" {
loopback loop /iso_boot/lubuntu-14.04.1-desktop-i386.iso
set gfxpayload=keep
linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=/iso_boot/lubuntu-14.04.1-desktop-i386.iso noeject noprompt --
initrd (loop)/casper/initrd.lz
}

menuentry "kali linux 1.0.3 live" {
set iso_file=/iso_boot/kali-linux-1.0.3-amd64.iso
loopback loop $iso_file
linux (loop)/live/vmlinuz boot=live noconfig=sudo username=root hostname=kali noswap noautomount
initrd (loop)/live/initrd.img
}

menuentry "TinyCore Pure64 6.2" {
set iso_file=/iso_boot/TinyCorePure64-6.2.iso
loopback loop $iso_file
linux (loop)/boot/vmlinuz64 loglevel=3 cde vga=normal
initrd (loop)/boot/corepure64.gz
}

Finally modify the ~/multiboot/boot/grub/grub.cfg file according to your need.

Complete ! Now you can use this USB drive to boot multiple Linux live CDs.

Further reading > Write your own GRUB menu entry

1. mount the Linux installer ISO file of your choice.
2. find the path and name of kernel.
3. find the path and name of initrd.
4. find the boot time kernel parameters, usually find in the syslinux.cfg or grub.cfg file
5. write down them in the ~/multiboot/boot/grub/grub.cfg file.

An example grub menu entry

menuentry "My Distro Name" {
set iso_file=/path/to/your_iso_file.iso
loopback loop $iso_file
linux (loop)/path/to/your_kernel your_distro_spacific_boot_time_kernel_parameters
initrd (loop)/path/to/your_initrd_file
}

Conclusion

So, that's it 🙂 . Follow this tutorial and create your own grub configuration to make a multiboot USB. This bootable USB also could be used for GRUB rescue and recovery.

Don't forget to share your experience with us via comments. Also if you need any help just leave a comment.