shred

is a command on Unix-like operating systems that can be used to securely delete files and devices so that it is extremely difficult to recover them, even with specialized hardware and technology; assuming it's even possible to recover the file at all. It is a part of GNU Core Utilities. Being based on the Gutmann method paper, it suffers from the same criticisms and possible shortcomings. Background For efficiency, the process of erasing a file from storage using the command usually only erases the file's file-system entry while keeping the content of the file intact. This frequently allows commonly available software to recover the "erased" file's data. If the file data is stored on magnetic media such as a HDD, even if the file is overwritten, residual magnetic fields may allow data recovery using specialist hardware equipment (this claim is disputed; see ). To prevent this, overwrites the contents of a file multiple times, using patterns chosen to maximize destruction of the residual data. Features can be invoked either on ordinary files or on devices (such as hard disk partitions), which are represented as files in Unix. By default, the command overwrites the file three times with multiple patterns, but the number is user configurable. It has an option to do an additional final overwrite with zeroes, which may help to hide the fact that it was used.