153 lines
5.3 KiB
Groff
153 lines
5.3 KiB
Groff
.\" Copyright 2009 by Karel Zak. All Rights Reserved.
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.\" This file may be copied under the terms of the GNU Public License.
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.\"
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.TH WIPEFS 8 "December 2014" "util-linux" "System Administration"
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.SH NAME
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wipefs \- wipe a signature from a device
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.SH SYNOPSIS
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.B wipefs
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.RB [ options ]
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.IR device ...
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.sp
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.B wipefs
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.RB [ \-\-backup ]
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.B \-o
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.I offset
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.IR device ...
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.sp
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.B wipefs
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.RB [ \-\-backup ]
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.B \-a
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.IR device ...
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.SH DESCRIPTION
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.B wipefs
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can erase filesystem, raid or partition-table signatures (magic strings) from
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the specified
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.I device
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to make the signatures invisible for libblkid.
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.B wipefs
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does not erase the filesystem itself nor any other data from the device.
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When used without any options,
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.B wipefs
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lists all visible filesystems and the
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offsets of their basic signatures. The default output is subject to change.
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So whenever possible, you should avoid using default outputs in your scripts.
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Always explicitly define expected columns by using
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.B \-\-output
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.I columns-list
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in environments where a stable output is required.
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.B wipefs
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calls the BLKRRPART ioctl when it has erased a partition-table signature
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to inform the kernel about the change. The ioctl is called as the last step
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and when all specified signatures from all specified devices are already erased.
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This feature can be used to wipe content on partitions devices as well as partition
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table on a disk device, for example by \fBwipefs \-a /dev/sdc1 /dev/sdc2 /dev/sdc\fR.
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Note that some filesystems and some partition tables store more magic strings on
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the device (e.g., FAT, ZFS, GPT). The
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.B wipefs
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command (since v2.31) lists all the offset where a magic strings have been
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detected.
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When option \fB\-a\fR is used, all magic strings that are visible for libblkid are
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erased. In this case the
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.B wipefs
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scans the device again after each modification (erase) until no magic string is found.
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Note that by default
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.B wipefs
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does not erase nested partition tables on non-whole disk devices.
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For this the option \fB\-\-force\fR is required.
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.SH OPTIONS
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.TP
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.BR \-a , " \-\-all"
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Erase all available signatures. The set of erased signatures can be
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restricted with the \fB\-t\fR option.
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.TP
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.BR \-b , " \-\-backup"
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Create a signature backup to the file $HOME/wipefs-<devname>-<offset>.bak.
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For more details see the \fBEXAMPLE\fR section.
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.TP
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.BR \-f , " \-\-force"
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Force erasure, even if the filesystem is mounted. This is required in
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order to erase a partition-table signature on a block device.
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.TP
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.BR \-h , " \-\-help"
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Display help text and exit.
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.TP
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.BR \-J , " \-\-json"
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Use JSON output format.
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.TP
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\fB\-\-lock\fR[=\fImode\fR]
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Use exclusive BSD lock for device or file it operates. The optional argument
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\fImode\fP can be \fByes\fR, \fBno\fR (or 1 and 0) or \fBnonblock\fR. If the \fImode\fR
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argument is omitted, it defaults to \fB"yes"\fR. This option overwrites
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environment variable \fB$LOCK_BLOCK_DEVICE\fR. The default is not to use any
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lock at all, but it's recommended to avoid collisions with udevd or other
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tools.
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.TP
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.BR \-i , " \-\-noheadings"
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Do not print a header line.
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.TP
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.BR \-O , " \-\-output " \fIlist\fP
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Specify which output columns to print. Use
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.B \-\-help
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to get a list of all supported columns.
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.TP
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.BR \-n , " \-\-no\-act"
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Causes everything to be done except for the write() call.
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.TP
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.BR \-o , " \-\-offset " \fIoffset\fP
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Specify the location (in bytes) of the signature which should be erased from the
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device. The \fIoffset\fR number may include a "0x" prefix; then the number will be
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interpreted as a hex value. It is possible to specify multiple \fB\-o\fR options.
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.sp
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The \fIoffset\fR argument may be followed by the multiplicative
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suffixes KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB
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(the "iB" is optional, e.g., "K" has the same meaning as "KiB"), or the suffixes
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KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB.
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.TP
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.BR \-p , " \-\-parsable"
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Print out in parsable instead of printable format. Encode all potentially unsafe
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characters of a string to the corresponding hex value prefixed by '\\x'.
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.TP
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.BR \-q , " \-\-quiet"
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Suppress any messages after a successful signature wipe.
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.TP
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.BR \-t , " \-\-types " \fIlist\fP
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Limit the set of printed or erased signatures. More than one type may
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be specified in a comma-separated list. The list or individual types
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can be prefixed with 'no' to specify the types on which no action should be
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taken. For more details see
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.BR mount (8).
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.TP
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.BR \-V , " \-\-version"
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Display version information and exit.
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.SH ENVIRONMENT
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.IP LIBBLKID_DEBUG=all
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enables libblkid debug output.
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.IP LOCK_BLOCK_DEVICE=<mode>
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use exclusive BSD lock. The mode is "1" or "0". See \fB\-\-lock\fR for more details.
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.SH EXAMPLE
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.TP
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.B wipefs /dev/sda*
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Prints information about sda and all partitions on sda.
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.TP
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.B wipefs \-\-all \-\-backup /dev/sdb
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Erases all signatures from the device /dev/sdb and creates a signature backup
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file \(ti/wipefs-sdb-<offset>.bak for each signature.
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.TP
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.B dd if=\(ti/wipefs-sdb-0x00000438.bak of=/dev/sdb seek=$((0x00000438)) bs=1 conv=notrunc
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Restores an ext2 signature from the backup file \(ti/wipefs-sdb-0x00000438.bak.
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.SH AUTHORS
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Karel Zak <kzak@redhat.com>
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.SH SEE ALSO
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.BR blkid (8),
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.BR findfs (8)
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.SH AVAILABILITY
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The wipefs command is part of the util-linux package and is available from
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https://www.kernel.org/pub/linux/utils/util-linux/.
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