Identify Your USB Device

sudo lsblk
#or
sudo fdisk -l

#output from fdisk -l
Disk /dev/sda: 28.65 GiB, 30765219840 bytes, 60088320 sectors
Device     Boot Start      End  Sectors  Size Id Type
/dev/sda1        2048 60088286 60086239 28.7G 83 Linux
  • Your device will likely be something like /dev/sd*. (copy dev/sda only, not /dev/sda1)

Unmount USB (Depends)

  • Unmount the partition in case you have mounted it:
    sudo umount /dev/sda1

Format USB (Optional)

  • This step is an optional step, mainly because dd command writes the ISO bit-for-bit, completely overwriting any existing partitions or filysystems on the USB stick.
  • I’m formatting the USB device in ext4 format:
    sudo mkfs.ext4 /dev/sda

Write ISO to USB using dd

  • Locate the *.iso file you want to flash
sudo dd \
> if=/home/$USER/debian-12.11.0-amd64-netinst.iso \
> of=/dev/sda1 \
> bs=4M \
> status=progress \
> oflag=sync
  • if=: Input File | Path to your ISO
  • of=: Output Path | USB device /dev/sda (not the partition /dev/sda1)
  • bs=4M: Sets block size for faster copying | Uses 4MB for each operation
  • status=progress: Shows progress bar
  • oflag=sync: Ensures data is physically written to the USB before finishing.