Mount the ISO:

  sudo mount -t udf -o loop,ro,unhide /path/to/file.iso /mnt

Insert the USB drive.

Run fdisk and specify the device name of the USB drive; for example:

  sudo fdisk /dev/sdc

  * Delete any existing partition table and create a new one.
  * Create a new partition of at least 4.5 GB. Mark it bootable and set its type to 7 (HPFS/NTFS/ExFAT).
  * Write changes and exit fdisk.

Create a FAT-32 file system in the new partition; for example:

  sudo mkfs.vfat -F 32 /dev/sdc1

Mount this partition to an existing subdirectory; for example:

  sudo mount /dev/sdc1 /media/usbstick

Copy all of the files from the mounted ISO into this directory:

  sudo cp -rv /mnt/* /media/usbstick

Sync the file systems just to be sure:

  sudo sync

Unmount both items previously mounted:

  sudo umount /media/usbstick
  sudo umount /mnt