.\" -*- nroff -*-
.\" Copyright 2009 by Karel Zak.  All Rights Reserved.
.\" This file may be copied under the terms of the GNU Public License.
.\"
.TH WIPEFS 8 "October 2009" "util-linux" "System Administration"
.SH NAME
wipefs \- wipe a signature from a device
.SH SYNOPSIS
.B wipefs
.RB [ \-ahnpqtV ]
.RB [ \-o
.IR offset ]
.IR device ...
.SH DESCRIPTION
.B wipefs
can erase filesystem, raid or partition-table signatures (magic strings) from
the specified
.I device
to make the signatures invisible for libblkid.

.B wipefs
does not erase the filesystem itself nor any other data from the device.
When used without options \fB-a\fR or \fB-o\fR, it lists all visible filesystems
and the offsets of their basic signatures.

.B wipefs
calls BLKRRPART ioctl when erase partition table to inform kernel about the change.

Note that some filesystems or some partition tables store more magic strings on
the devices.  The
.B wipefs
command lists only the first offset where a magic string has been detected.  The device
is not scanned for additional magic strings for the same filesystem.  It is possible
that after \fBwipefs -o \fIoffset\fR the same filesystem or partition
table will still be visible by another magic string on another offset.

When used with option \fB-a\fR, all magic strings that are visible for libblkid are
erased.

Note that by default
.B wipefs
does not erase nested partition tables on non-whole disk devices. The option 
\-\-force is required.

.SH OPTIONS
.TP
.BR \-a , " \-\-all"
Erase all available signatures.  The set of erased signatures can be
restricted with the \fB\-t\fP \fIlist\fP option.
.TP
.BR \-b , " \-\-backup"
Create a signature backup to the file $HOME/wipefs-<devname>-<offset>.bak.
For more details see EXAMPLES section.
.TP
.BR \-f , " \-\-force"
Force erasure, even if the filesystem is mounted.  This is required in
order to erase the partition table on a block device.
.TP
.BR \-h , " \-\-help"
Display help text and exit.
.TP
.BR -n , " \-\-no\-act"
Causes everything to be done except for the write() call.
.TP
.BR \-o , " \-\-offset " \fIoffset\fP
Specify the location (in bytes) of the signature which should be erased from the
device.  The \fIoffset\fR number may include a "0x" prefix; then the number will be
interpreted as a hex value.  It is possible to specify multiple \fB-o\fR options.

The \fIoffset\fR argument may be followed by the multiplicative
suffixes KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB
(the "iB" is optional, e.g. "K" has the same meaning as "KiB"), or the suffixes
KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB.
.TP
.BR \-p , " \-\-parsable"
Print out in parsable instead of printable format.  Encode all potentially unsafe
characters of a string to the corresponding hex value prefixed by '\\x'.
.TP
.BR \-q , " \-\-quiet"
Suppress output messages after successful signature wipe.
.TP
.BR \-t , " \-\-types " \fIlist\fP
Limit the set of printed or erased signatures.  More than one type may
be specified in a comma-separated list.  The list or individual types
can be prefixed with 'no' to specify the types on which no action should be
taken.  For more details see mount(8).
.TP
.BR -V , " \-\-version"
Display version information and exit.
.SH EXAMPLES
.TP
.BR "wipefs --all --backup /dev/sdb"
Erases all signatures from the device /dev/sdb and creates a signature backup
file ~/wipefs-sdb-<offset>.bak for each signature.
.TP
.BR "dd if=~/wipefs-sdb-0x00000438.bak of=/dev/sdb seek=$((0x00000438)) bs=1 conv=notrunc"
Restores ext2 signature from the backup file  ~/wipefs-sdb-0x00000438.bak.
.SH AUTHOR
Karel Zak <kzak@redhat.com>
.SH ENVIRONMENT
.IP "Setting LIBBLKID_DEBUG=0xffff enables debug output."
.SH SEE ALSO
.BR blkid (8),
.BR findfs (8)
.SH AVAILABILITY
The wipefs command is part of the util-linux package and is available from
ftp://ftp.kernel.org/pub/linux/utils/util-linux/.