How to create bootable USB drive from an ISO image in Linux

ISO images, typically distributed in ISO 9660 format, are commonly used for distributing bootable operating system installers. This format is designed for optical discs and can contain both data and a boot sector, enabling the image to be bootable. By burning ISO images directly onto a USB stick or portable hard drive, you can boot from the external device.

In Linux, there are several tools available for creating a bootable USB drive from an ISO image. Among these, the dd command-line tool is the most universally available and comes preinstalled in most Linux distributions, such as Ubuntu, Fedora, CentOS, and SUSE.

1. Open a terminal application..
2. Verify that your ISO image is in the correct ISO 9660 format and is bootable.

   $ file Downloads/ubuntu-21.04-desktop-amd64.iso 
   Downloads/ubuntu-21.04-desktop-amd64.iso: ISO 9660 CD-ROM filesystem data (DOS/MBR boot sector) 'Ubuntu 21.04 amd64' (bootable)

3. List the available block devices on your system.

   $ lsblk
   NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
   loop0    7:0    0 55.4M  1 loop /snap/core18/1997
   loop1    7:1    0  219M  1 loop /snap/gnome-3-34-1804/66
   loop2    7:2    0 64.8M  1 loop /snap/gtk-common-themes/1514
   loop3    7:3    0 32.3M  1 loop /snap/snapd/11588
   loop4    7:4    0   51M  1 loop /snap/snap-store/518
   loop5    7:5    0 65.1M  1 loop /snap/gtk-common-themes/1515
   sda      8:0    0   20G  0 disk 
   sdb      8:16   0   20G  0 disk 
   ├─sdb1   8:17   0    1M  0 part 
   ├─sdb2   8:18   0  513M  0 part /boot/efi
   └─sdb3   8:19   0 19.5G  0 part /
   sr0     11:0    1 1024M  0 rom

4. Insert your USB drive and wait a few seconds for the system to detect it.
5. Identify the device name of your newly inserted USB drive.

   $ lsblk
   NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
   loop0    7:0    0 55.4M  1 loop /snap/core18/1997
   loop1    7:1    0  219M  1 loop /snap/gnome-3-34-1804/66
   loop2    7:2    0 64.8M  1 loop /snap/gtk-common-themes/1514
   loop3    7:3    0 32.3M  1 loop /snap/snapd/11588
   loop4    7:4    0   51M  1 loop /snap/snap-store/518
   loop5    7:5    0 65.1M  1 loop /snap/gtk-common-themes/1515
   sda      8:0    0   20G  0 disk 
   sdb      8:16   0   20G  0 disk 
   ├─sdb1   8:17   0    1M  0 part 
   ├─sdb2   8:18   0  513M  0 part /boot/efi
   └─sdb3   8:19   0 19.5G  0 part /
   sdc      8:32   1 58.6G  0 disk 
   ├─sdc1   8:33   1  2.5G  0 part /media/user/Ubuntu 20.04 LTS amd64
   └─sdc2   8:34   1  3.9M  0 part /media/user/1079-24A3
   sr0     11:0    1 1024M  0 rom  

6. Ensure that none of the partitions on your USB drive are mounted.

   $ sudo umount /dev/sdc1 /dev/sdc2
   [sudo] password for user:

7. Use the dd command to copy the ISO image to your USB drive.

   $ sudo dd if=Downloads/ubuntu-21.04-desktop-amd64.iso of=/dev/sdc conv=fdatasync
   5505348+0 records in
   5505348+0 records out
   2818738176 bytes (2.8 GB, 2.6 GiB) copied, 628.961 s, 4.5 MB/s

   Related: How to monitor progress of dd command

8. Verify that the ISO image was successfully copied to your USB drive.

   $ sudo blkid /dev/sdc
   /dev/sdc: BLOCK_SIZE="2048" UUID="2021-04-20-11-16-16-00" LABEL="Ubuntu 21.04 amd64" TYPE="iso9660" PTUUID="af8737a9-1e23-4373-b87a-c8b16199d461" PTTYPE="gpt"

9. Safely remove your USB drive from the machine.