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

Trace: • makebootusb