How to write an iso file to usb driver

The command we are going to issue to dd is as follows:

sudo dd bs=4M if=Downloads/ubuntu-19.04-desktop-amd64.iso of=/dev/sdb conv=fdatasync

Let’s break that down.

• sudo: You need to be a superuser to issue dd commands. You will be prompted for your password.
• dd: The name of the command we’re using.
• bs=4M: The -bs (blocksize) option defines the size of each chunk that is read from the input file and wrote to the output device. 4 MB is a good choice because it gives decent throughput and it is an exact multiple of 4 KB, which is the blocksize of the ext4 filesystem. This gives an efficient read and write rate.
• if=Downloads/ubuntu-19.04-desktop-amd64.iso: The -if (input file) option requires the path and name of the Linux ISO image you are using as the input file.
• of=/dev/sdb: The -of (output file) is the critical parameter. This must be provided with the device that represents your USB drive. This is the value we identified by using the lsblk command previously. in our example it is sdb, so we are using /dev/sdb. Your USB drive might have a different identifier. Make sure you provide the correct identifier.
• conv=fdatasync: The conv parameter dictates how dd converts the input file as it is written to the output device. dd uses kernel disk caching when it writes to the USB drive. The fdatasync modifier ensure the write buffers are flushed correctly and completely before the creation process is flagged as having finished.

There is no visual feedback from dd at all as the creation progress takes place. It goes to work and doesn’t report anything until it has finished.

Update: In recent versions, dd now has a status=progress option that provides updates on the process once per second.  For example, you could run this command instead to see the status:

sudo dd bs=4M if=Downloads/ubuntu-19.04-desktop-amd64.iso of=/dev/sdb conv=fdatasync status=progerss

When the bootable USB drive has been created dd reports the amount of data that was written to the USB drive, the elapsed time in seconds and the average data transfer rate.

You can check the bootable USB drive works by rebooting your computer and booting from the USB drive, or you can try booting from it in another computer.

You now have a portable working copy of Ubuntu or another Linux distribution of your choice. It will be pristine every time you boot it, and you can boot it on practically any PC you like.