/usr/bin/shred

Usage: /usr/bin/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 details of data and metadata operations performed
  -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

FILE will be skipped with a diagnostic message if it is a FIFO, socket, or
terminal, since its data does not reside on disk.

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.

Report bugs to: <bug-coreutils@gnu.org>.
GNU coreutils home page: <https://www.gnu.org/software/coreutils/>
General help using GNU software: <https://www.gnu.org/gethelp/>
Full documentation <https://www.gnu.org/software/coreutils/shred>
or available locally via: info '(coreutils) shred invocation'