


SHRED(1)                       FSF                       SHRED(1)


NAME
       shred  -  delete  a file securely, first overwriting it to
       hide its contents

SYNOPSIS
       shred [OPTIONS] FILE [...]

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

       -f, --force
              change permissions to allow writing if necessary

       -n, --iterations=N
              Overwrite N times instead of the default (25)

       -s, --size=N
              shred this  many  bytes  (suffixes  like  k,  M,  G
              accepted)

       -u, --remove
              truncate and remove file after overwriting

       -v, --verbose
              show progress

       -x, --exact
              do not round file sizes up to the next full block

       -z, --zero
              add a final overwrite with zeros to hide shredding

       -      shred standard output

       --help display this help and exit

       --version
              print 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.  When operating on  regular  files,
       most people use the --remove option.

       CAUTION:  Note  that  shred  relies  on  a  very important
       assumption: that the filesystem overwrites data in  place.
       This  is the traditional way to do things, but many modern
       filesystem designs do not satisfy  this  assumption.   The
       following  are  examples  of filesystems on which shred is
       not effective:




shred (fileutils) 4.1       April 2002                          1





SHRED(1)                       FSF                       SHRED(1)


       * log-structured or journaled filesystems, such  as  those
       supplied with

              AIX and Solaris (and JFS, ReiserFS, XFS, etc.)

       *  filesystems that write redundant data and carry on even
       if some writes

              fail, such as RAID-based filesystems

       * filesystems that make snapshots, such as Network  Appli-
       ance's NFS server

       *  filesystems  that cache in temporary locations, such as
       NFS

              version 3 clients

       * compressed filesystems

AUTHOR
       Written by Colin Plumb.

REPORTING BUGS
       Report bugs to <bug-fileutils@gnu.org>.

COPYRIGHT
       Copyright (C) 2001 Free Software Foundation, Inc.
       This is free software; see the source for  copying  condi-
       tions.  There is NO warranty; not even for MERCHANTABILITY
       or FITNESS FOR A PARTICULAR PURPOSE.

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

              info shred

       should give you access to the complete manual.

















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