shred - overwrite a file to hide its contents, and optionally delete it

NAME SYNOPSIS DESCRIPTION AUTHOR REPORTING BUGS COPYRIGHT SEE ALSO

NAME

shred − overwrite a file to hide its contents, and optionally delete it

DESCRIPTION

Overwrite the specified FILE(s) repeatedly, in order to make it harder for even very expensive hardware probing to recover the data.

If FILE is −, shred standard output.

Mandatory arguments to long options are mandatory for short options too.
−f, −−force

change permissions to allow writing if necessary

−n, −−iterations=N

overwrite N times instead of the default (3)

−−random−source=FILE

get random bytes from FILE

−s, −−size=N

shred this many bytes (suffixes like K, M, G accepted)

−u

deallocate and remove file after overwriting

−−remove[=HOW]

like −u but give control on HOW to delete; See below

−v, −−verbose

show progress

−x, −−exact

do not round file sizes up to the next full block;

this is the default for non−regular files

−z, −−zero

add a final overwrite with zeros to hide shredding

−−help

display this help and exit

−−version

output version information and exit

Delete FILE(s) if −−remove (−u) is specified. The default is not to remove the files because it is common to operate on device files like /dev/hda, and those files usually should not be removed. The optional HOW parameter indicates how to remove a directory entry: ’unlink’ => use a standard unlink call. ’wipe’ => also first obfuscate bytes in the name. ’wipesync’ => also sync each obfuscated byte to the device. The default mode is ’wipesync’, but note it can be expensive.

CAUTION: shred assumes the file system and hardware overwrite data in place. Although this is common, many platforms operate otherwise. Also, backups and mirrors may contain unremovable copies that will let a shredded file be recovered later. See the GNU coreutils manual for details.