https://unix.stackexchange.com/questions/328156/create-virtual-usb-drive

fallocate -l 4000M /mnt/virtual_usb.img

mkfs.ext4 -E lazy_itable_init=1 /mnt/virtual_usb.img

mkdir /mnt/virtual_mount

mount -t auto -o loop /mnt/virtual_usb.img /mnt/virtual_mount