SHRED(1) FSF SHRED(1)NAMEshred - delete a file securely, first overwriting it to
hide its contents
SYNOPSISshred [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 April 2001 SHRED(1)
