Although it has some important limitations, the shred command
can be useful for destroying files so that their contents are
very difficult or impossible to recover. shred accomplishes its
destruction by repeatedly overwriting files with data patterns
designed to do maximum damage so that it becomes difficult to
recover data even using high-sensitivity data recovery
equipment1. Deleting a file with the rm command does not
actually destroy the data; it merely destroys an index listing
the location of the file and makes the file's data blocks
available for reuse. Thus, a file deleted with rm can be easily
recovered using special utilities or commands if its freed data
blocks have not yet been reused. However, on an active system
with a nearly full hard disk drive (HDD), freed space can be
reused in a matter of minutes or even seconds. shred's syntax is
When used without any options, shred will overwrite any
designated files or devices 25 times, which is generally
sufficient to remove all traces of the data on th