Man1 - shred.1

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

shred [/OPTION/]… FILE…

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.

Written by Colin Plumb.

GNU coreutils online help: https://www.gnu.org/software/coreutils/
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Copyright © 2021 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later https://gnu.org/licenses/gpl.html.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

Full documentation https://www.gnu.org/software/coreutils/shred
or available locally via: info ’(coreutils) shred invocation’