Install scrub by entering the following commands in the terminal:
sudo apt update sudo apt install scrub
Description:
writes patterns on magnetic media to thwart data recovery
scrub iteratively writes patterns on files or disk devices to make retrieving the data more difficult. . scrub can write patterns direct to disk, destroying any file system (preferred method), or it can write patterns on files, or on file system free space. . scrub writes NNSA NAP-14.x, DoD 5220.22-M, BSI, 35-pass gutmann, or one of several other selectable pattern sequences. . scrub operates at the POSIX system call level, thus it is portable to a wide variety of hardware platforms. However, this means it cannot do certain things like manipulate spare blocks on disks, etc..
Homepage: http://code.google.com/p/diskscrub/
Version: 2.6.1-1build1
Section: universe/utils