NAME

       shred - overwrite a file to hide its contents, and optionally delete it

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.

       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     truncate and remove file after overwriting

       --remove[=HOW]
              like -u but give control on HOW to delete;  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

       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 the file system overwrites data in
       place.  This is the traditional way to do things, but many modern file system designs do not satisfy this
       assumption.  The following are examples of file systems on which  shred  is  not  effective,  or  is  not
       guaranteed to be effective in all file system modes:

       *  log-structured  or  journaled  file  systems,  such  as  those supplied with AIX and Solaris (and JFS,
       ReiserFS, XFS, Ext3, etc.)

       * file systems that write redundant data and carry on even if some writes fail, such as  RAID-based  file
       systems

       * file systems that make snapshots, such as Network Appliance's NFS server

       * 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.

AUTHOR

       Written by Colin Plumb.

REPORTING BUGS

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

COPYRIGHT

       Copyright  ©  2017  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

       Full documentation at: <http://www.gnu.org/software/coreutils/shred>
       or available locally via: info '(coreutils) shred invocation'

GNU coreutils 8.28                                January 2018                                          SHRED(1)