-.\" -*- 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"
+.TH WIPEFS 8 "December 2014" "util-linux" "System Administration"
.SH NAME
wipefs \- wipe a signature from a device
.SH SYNOPSIS
.B wipefs
-.RB [ \-ahnpqtV ]
-.RB [ \-o
-.IR offset ]
+.RB [ options ]
+.IR device ...
+.sp
+.B wipefs
+.RB [ \-\-backup ]
+.B \-o
+.I offset
+.IR device ...
+.sp
+.B wipefs
+.RB [ \-\-backup ]
+.B \-a
.IR device ...
.SH DESCRIPTION
.B wipefs
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.
+
+When used without any options, wipefs lists all visible filesystems and the
+offsets of their basic signatures. The default output is subject to change.
+So whenever possible, you should avoid using default outputs in your scripts.
+Always explicitly define expected columns by using
+.B \-\-output
+.I columns-list
+in environments where a stable output is required.
.B wipefs
-calls BLKRRPART ioctl when erase partition table to inform kernel about the change.
+calls the BLKRRPART ioctl when it has erased a partition-table signature
+to inform the kernel about the change. The ioctl is called as the last step
+and when all specified signatures from all specified devices are already erased.
-Note that some filesystems or some partition tables store more magic strings on
-the devices. The
+Note that some filesystems and some partition tables store more magic strings on
+the device (e.g. FAT, ZFS, GPT). 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.
+command (since v2.31) lists all the offset where a magic strings have been
+detected.
-When used with option \fB-a\fR, all magic strings that are visible for libblkid are
-erased.
+When option \fB-a\fR is used, all magic strings that are visible for libblkid are
+erased. In this case the
+.B wipefs
+scans the device again after each modification (erase) until no magic string is found.
Note that by default
.B wipefs
-does not erase nested partition tables on non-whole disk devices. The option
-\-\-force is required.
+does not erase nested partition tables on non-whole disk devices.
+For this the option \fB\-\-force\fR 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.
+restricted with the \fB\-t\fR option.
.TP
.BR \-b , " \-\-backup"
Create a signature backup to the file $HOME/wipefs-<devname>-<offset>.bak.
-For more details see EXAMPLES section.
+For more details see the \fBEXAMPLES\fR section.
.TP
.BR \-f , " \-\-force"
Force erasure, even if the filesystem is mounted. This is required in
-order to erase the partition table on a block device.
+order to erase a partition-table signature on a block device.
.TP
.BR \-h , " \-\-help"
Display help text and exit.
.TP
+.BR \-J , " \-\-json"
+Use JSON output format.
+.TP
+.BR \-n , " \-\-noheadings"
+Do not print a header line.
+.TP
+.BR \-O , " \-\-output " \fIlist\fP
+Specify which output columns to print. Use \-\-help to
+get a list of all supported columns.
+.TP
.BR -n , " \-\-no\-act"
Causes everything to be done except for the write() call.
.TP
Specify the location (in bytes) of the signature which should be erased from the
device. The \fIoffset\fR number may include a "0x" prefix; then the number will be
interpreted as a hex value. It is possible to specify multiple \fB-o\fR options.
-
+.sp
The \fIoffset\fR argument may be followed by the multiplicative
suffixes KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB
(the "iB" is optional, e.g. "K" has the same meaning as "KiB"), or the suffixes
characters of a string to the corresponding hex value prefixed by '\\x'.
.TP
.BR \-q , " \-\-quiet"
-Suppress output messages after successful signature wipe.
+Suppress any messages after a successful signature wipe.
.TP
.BR \-t , " \-\-types " \fIlist\fP
Limit the set of printed or erased signatures. More than one type may
Display version information and exit.
.SH EXAMPLES
.TP
-.BR "wipefs --all --backup /dev/sdb"
+.B wipefs /dev/sda*
+Prints information about sda and all partitions on sda.
+.TP
+.B wipefs --all --backup /dev/sdb
Erases all signatures from the device /dev/sdb and creates a signature backup
file ~/wipefs-sdb-<offset>.bak for each signature.
.TP
-.BR "dd if=~/wipefs-sdb-0x00000438.bak of=/dev/sdb seek=$((0x00000438)) bs=1 conv=notrunc"
-Restores ext2 signature from the backup file ~/wipefs-sdb-0x00000438.bak.
+.B dd if=~/wipefs-sdb-0x00000438.bak of=/dev/sdb seek=$((0x00000438)) bs=1 conv=notrunc
+Restores an 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."
+.IP LIBBLKID_DEBUG=all
+enables libblkid 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/.
+https://www.kernel.org/pub/linux/utils/util-linux/.
projects / thirdparty / util-linux.git / blobdiff