Manual: shred

SHRED(1)					   General Commands Manual					    SHRED(1)

NAME
       shred - Overwrite the specified FILE(s) repeatedly, in order to make it harder for even very expensive hardware prob‐
       ing to recover the data.

SYNOPSIS
       shred  [-f|--force]  [-n|--iterations]  [-s|--size]  [-u ] [--remove] [-v|--verbose] [-x|--exact] [-z|--zero] [--ran‐
       dom-source] [-h|--help] [-V|--version] [file]

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

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

       -n, --iterations  [default: 3]
	      overwrite N times instead of the default (3)

       -s, --size 
	      shred this many bytes (suffixes like K, M, G accepted)

       -u     deallocate and remove file after overwriting

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

	      Possible values:

		     • unlink

		     • wipe

		     • wipesync

       -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

       --random-source
	      take random bytes from FILE

       -h, --help
	      Print help

       -V, --version
	      Print version

       [file]

EXTRA
       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.

       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 follow‐
       ing 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 journal 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 journal 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.

VERSION
       v(uutils coreutils) 0.8.0

							 2026-04-16						    SHRED(1)