How do I write a CD image to a USB flash drive?

Several of the Debian CD and Debian Live images are created using isohybrid technology, which means that they may be used in two different ways:

  • They may be written to CD/DVD and used as normal for CD/DVD booting.
  • They may be written to USB flash drives, bootable directly from the BIOS of most PCs.

The most common way to copy an image to a USB flash drive is to use the dd command on a Linux machine:

dd if=<file> of=<device> bs=4M; sync


  • <file> is the name of the input image, e.g. netinst.iso
  • <device> is the device matching the USB flash drive, e.g. /dev/sda, /dev/sdb. Be careful to make sure you have the right device name, as this command is capable of writing over your hard disk just as easily if you get the wrong one!
  • bs=4M tells dd to read/write in 4 megabyte chunks for better performance; the default is 512 bytes, which will be much slower
  • The sync is to make sure that all the writes are flushed out before the command returns.