How to make a bootable USB with GRUB2 and ISO
Do you have multiple ISO files to install, with quite enough storage of USB stick? You’ll want to install all of them with a single USB stick. Here’s how.
Formatting USB disk
First, plug in your USB stick and find it from your Linux machine:
$ sudo fdisk -l
Disk /dev/sda: 20 GiB, 21474836480 bytes, 41943040 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x4d149927
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 39845887 39843840 19G 83 Linux
/dev/sda2 39847934 41940991 2093058 1022M 5 Extended
/dev/sda5 39847936 41940991 2093056 1022M 82 Linux swap / Solaris
Disk /dev/sdb: 14.6 GiB, 15664676864 bytes, 30595072 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 4788154A-7BD2-4A06-945B-5980E828C8C5
Device Start End Sectors Size Type
/dev/sdb1 40 409639 409600 200M EFI System
/dev/sdb2 411648 30593023 30181376 14.4G Microsoft basic data
In my case, it’s /dev/sdb. Let’s format it with fdisk. When you run fdisk /dev/sdb, you can print help menu:
$ sudo fdisk /dev/sdb
Welcome to fdisk (util-linux 2.27.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): m
Help:
Generic
d delete a partition
F list free unpartitioned space
l list known partition types
n add a new partition
p print the partition table
t change a partition type
v verify the partition table
i print information about a partition
Misc
m print this menu
x extra functionality (experts only)
Script
I load disk layout from sfdisk script file
O dump disk layout to sfdisk script file
Save & Exit
w write table to disk and exit
q quit without saving changes
Create a new label
g create a new empty GPT partition table
G create a new empty SGI (IRIX) partition table
o create a new empty DOS partition table
s create a new empty Sun partition table
Now we can start!
$ sudo fdisk /dev/sdb
Welcome to fdisk (util-linux 2.27.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): o
Created a new DOS disklabel with disk identifier 0x8c9faeb0.
Command (m for help): n
Partition type
p primary (0 primary, 0 extended, 4 free)
e extended (container for logical partitions)
Select (default p):
Using default response p.
Partition number (1-4, default 1):
First sector (2048-30595071, default 2048):
Last sector, +sectors or +size{K,M,G,T,P} (2048-30595071, default 30595071):
Created a new partition 1 of type 'Linux' and of size 14.6 GiB.
Command (m for help): t
Selected partition 1
Partition type (type L to list all types): c
Changed type of partition 'Linux' to 'W95 FAT32 (LBA)'.
Command (m for help): a
Selected partition 1
The bootable flag on partition 1 is enabled now.
Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
We’ve just created one bootable FAT partition, and that’ll be /dev/sdb1. Let’s create an MS-DOS filesystem in it. This will take a while.
$ sudo mkfs.vfat -F 32 /dev/sdb1
mkfs.fat 3.0.28 (2015-05-16)
Now you can mount that partition and we’re ready to install GRUB2 in it.
sudo mkdir /mnt/usb
sudo mount /dev/sdb1 /mnt/usb
Installing GRUB2
Since we’re installing GRUB2 into USB stick, we specify --removable flag. Also specify --boot-directory so that GRUB2 is installed to there instead of /boot/grub.
$ sudo grub-install --removable --boot-directory=/mnt/usb/boot /dev/sdb
Installing for i386-pc platform.
Installation finished. No error reported.
We’ll add grub.cfg file under /mnt/usb/boot/grub/ directory. It defines selectable menus and the booting method of each entry. This time I’ll add Ubuntu Desktop ISO for i386 platform.
set timeout=5
set default=0
menuentry "Ubuntu Desktop 16.04.3 LTS i386" {
set isofile="/iso/ubuntu-16.04.3-desktop-i386.iso"
loopback loop $isofile
linux (loop)/casper/vmlinuz boot=casper file=/preseed/ubuntu.seed iso-scan/filename=$isofile noeject noprompt splash --
initrd (loop)/casper/initrd.lz
}
menuentry "Ubuntu Desktop 16.04.3 LTS amd64" {
set isofile="/iso/ubuntu-16.04.3-desktop-amd64.iso"
loopback loop $isofile
linux (loop)/casper/vmlinuz.efi boot=casper file=/preseed/ubuntu.seed iso-scan/filename=$isofile noeject noprompt splash --
initrd (loop)/casper/initrd.lz
}
menuentry "Ubuntu Server 16.04.3 LTS i386" {
set isofile="/iso/ubuntu-16.04.3-server-i386.iso"
loopback loop $isofile
linux (loop)/install/vmlinuz boot=casper file=/preseed/ubuntu-server.seed iso-scan/filename=$isofile noeject noprompt splash --
initrd (loop)/install/initrd.gz
}
menuentry "Ubuntu Server 16.04.3 LTS amd64" {
set isofile="/iso/ubuntu-16.04.3-server-amd64.iso"
loopback loop $isofile
linux (loop)/install/vmlinuz boot=casper file=/preseed/ubuntu-server.seed iso-scan/filename=$isofile noeject noprompt splash --
initrd (loop)/install/initrd.gz
}
menuentry "Linux Mint 18.2 Cinnamon 32-bit" {
set isofile="/iso/linuxmint-18.2-cinnamon-32bit.iso"
loopback loop $isofile
linux (loop)/casper/vmlinuz boot=casper file=/preseed/linuxmint.seed iso-scan/filename=$isofile noeject noprompt splash --
initrd (loop)/casper/initrd.lz
}
menuentry "Custom ELF" {
elffile="/elf/custom.elf"
multiboot $elffile
}
In the first menuentry, isofile points to /iso/ubuntu-16.04.3-desktop-i386.iso, and it’s relative path of the USB stick. Create /mnt/usb/iso/ directory, and put the ISO files under there.
You may need to look inside of ISO file to find where is vmlinuz* and initrd.* files. Try this:
isoinfo -l -i myimage.iso
As the similar way, you can also make it to boot from ELF file. Just put the ELF file that supports Multiboot under /mnt/usb/elf/ directory, and edit the menuentry properly.
After editing is done, unmount the disk and use it right away!
sudo umount /dev/sdb1
Troubleshooting
If your screen goes black on boot, try with nomodeset:
linux ... noeject noprompt splash nomodeset --