shred

 

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 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:
 
        * 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 © 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.
 
 
 
 shred (fileutils) 4.1      August 2001                   SHRED(1)

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