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shred


SYNOPSIS

       shred [OPTION]... FILE...


DESCRIPTION

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

       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, --remove[=HOW]
              truncate and remove file after overwriting; 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

       If FILE is -, shred standard output.

       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  disk.   The
       default mode is 'wipesync', but note it can be expensive.

       CAUTION:  Note  that  shred relies on a very important assumption: that

       * file systems that cache in temporary locations, such as NFS version 3
       clients

       * compressed file systems

       In the case of ext3 file systems, the  above  disclaimer  applies  (and
       shred  is  thus  of  limited  effectiveness) only in data=journal mode,
       which journals file data in addition to just  metadata.   In  both  the
       data=ordered  (default) and data=writeback modes, shred works as usual.
       Ext3 journaling modes can  be  changed  by  adding  the  data=something
       option  to  the  mount  options  for  a  particular  file system in the
       /etc/fstab file, as documented in the mount man page (man mount).

       In addition, file system backups and remote mirrors may contain  copies
       of the file that cannot be removed, and that will allow a shredded file
       to be recovered later.

       GNU  coreutils  online  help:  <http://www.gnu.org/software/coreutils/>
       Report shred translation bugs to <http://translationproject.org/team/>


AUTHOR

       Written by Colin Plumb.


COPYRIGHT

       Copyright  (C) 2013 Free Software Foundation, Inc.  License GPLv3+: GNU
       GPL version 3 or later <http://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.


SEE ALSO

       The full documentation for shred is maintained as a Texinfo manual.  If
       the info and shred programs are properly installed at  your  site,  the
       command

              info coreutils 'shred invocation'

       should give you access to the complete manual.


GNU coreutils 8.22 November 2016 SHRED(1)



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