SHRED(1)                                  User Commands                                  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.

       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 (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;

              this is the default for non-regular files

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

       -      shred standard output

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

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

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

              AIX and Solaris (and JFS, ReiserFS, XFS, Ext3, 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 Appliance's NFS server

       * filesystems that cache in temporary locations, such as NFS

              version 3 clients

       * compressed filesystems

       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.

AUTHOR
       Written by Colin Plumb.

REPORTING BUGS
       Report bugs to <>.

COPYRIGHT
       Copyright (C) 2004 Free Software Foundation, Inc.
       This  is  free software; see the source for copying conditions.  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 Texinfo manual.  If the info and shred
       programs are properly installed at your site, the command

              info coreutils shred

       should give you access to the complete manual.



shred (coreutils) 5.2.1                   November 2008                                  SHRED(1)