Best dd options to write an ISO file to a USB flash drive

Every time I have to write an ISO file to a USB flash drive, I spend several minutes googling the right dd options to force sync writes, to use the right buffer size and to display the progress on the screen.

Thanks to my hobby of trying Linux distros and to re-install my desktop setup a couple of times a year, I repeat this process often enough, so here are my usual options for dd.

Buffer size #

Using a low buffer size will make this process to take forever. I have found that usually 4M is the right value: bs=4M

Sync write #

By default, dd makes use of the kernel buffer to write to the device. This is great if we are copying a small file but an ISO image is usually bigger than 1GB, so we want to use a value that allows dd to display the real data rate and ETA: oflag=sync

Show the progress #

By default, dd doesn't display the current progress status to the output. We can use status=progress to display it.

Other options #

• Remember to use sudo if you are writing to a device
• if= is the parameter for the input ISO file
• of= is the parameter for the ouput device

Summary #

Finally, these are all the options that usually work best for me:

sudo dd \
  if=image.iso \
  bs=4M \
  oflag=sync \
  of=/dev/DEVICE \
  status=progress

Example:

sudo dd \
  if=manjaro-mate-21.2.5-minimal-220314-linux515.iso \
  bs=4M \
  oflag=sync \
  of=/dev/sdb \
  status=progress

I hope this is helpful to more people and it's also a reminder for my future self.

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