$ sudo umount /dev/sdb1
$ sudo dd bs=4M if=/home/sana/Downloads/ubuntu-18.04.2-live-server-amd64.iso of=/dev/sdb1 status=progress oflag=sync
sudo dd bs=4M if=/home/praveen/Downloads/Win10_21H1_EnglishInternational_x32.iso of=/dev/sda1 status=progress oflag=sync
bootable usb