This utility writes patterns on files or disk devices to make retrieving the data more difficult. It operates in one of three modes:
1) the special file corresponding to an entire disk is scrubbed and all data on it is destroyed.
2) a regular file is scrubbed and only the data in the file (and optionally its name in the directory entry) is destroyed.
3) a regular file is created, expanded until the file system is full, then scrubbed as in 2).