Securely erasing a storage device

Shred command-line utility overwrites data in a file and in a whole device

Set all bits to zero after the last iteration by adding the option -z

•  sudo shred -v -n1 -z /dev/sdX

• After this is necessary to create partition 

                     sudo apt-get install gparted

                     sudo gparted

How to create bootable USB Media from ISO in Ubuntu Linux

1. Startup Disk Creator is a built-in application in Ubuntu Linux

2.  Convert iso file into bootable usb media  using ddrescue

• install ddrescue

                sudo apt update
                sudo apt install gddrescue

• check block device name

                sudo fdisk -l
                eg.  /dev/sdf

• enter the command as follows:

               sudo ddrescue Downloads/openSUSE-Leap-15.0-DVD-x86_64.iso /dev/sdf --force -D