man/cat1/shred.1.txt
|
SHRED(1) User Commands SHRED(1)
NAME shred - overwrite a file to hide its contents, and optionally delete it 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 shred- ding --help display this help and exit --version output version information and exit If FILE is -, shred standard output. 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 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: * 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 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 <bug-coreutils@gnu.org>. COPYRIGHT Copyright (C) 2005 Free Software Foundation, Inc. This is free software; see the source for copying condi- tions. There is NO warranty; not even for MERCHANTABIL- ITY 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 prop- erly installed at your site, the command info shred should give you access to the complete manual. shred 5.3.0 January 2005 SHRED(1) |