misc-utils/wipefs.8

   1 .\" Copyright 2009 by Karel Zak.  All Rights Reserved.
   2 .\" This file may be copied under the terms of the GNU Public License.
   3 .\"
   4 .TH WIPEFS 8 "December 2014" "util-linux" "System Administration"
   5 .SH NAME
   6 wipefs \- wipe a signature from a device
   7 .SH SYNOPSIS
   8 .B wipefs
   9 .RB [ options ]
  10 .IR device ...
  11 .sp
  12 .B wipefs
  13 .RB [ \-\-backup ]
  14 .B \-o
  15 .I offset
  16 .IR device ...
  17 .sp
  18 .B wipefs
  19 .RB [ \-\-backup ]
  20 .B \-a
  21 .IR device ...
  22 .SH DESCRIPTION
  23 .B wipefs
  24 can erase filesystem, raid or partition-table signatures (magic strings) from
  25 the specified
  26 .I device
  27 to make the signatures invisible for libblkid.
  28 .B wipefs
  29 does not erase the filesystem itself nor any other data from the device.
  30
  31 When used without any options, wipefs lists all visible filesystems and the
  32 offsets of their basic signatures.  The default output is subject to change.
  33 So whenever possible, you should avoid using default outputs in your scripts.
  34 Always explicitly define expected columns by using
  35 .B \-\-output
  36 .I columns-list
  37 in environments where a stable output is required.
  38
  39 .B wipefs
  40 calls the BLKRRPART ioctl when it has erased a partition-table signature
  41 to inform the kernel about the change. The ioctl is called as the last step
  42 and when all specified signatures from all specified devices are already erased.
  43
  44 Note that some filesystems and some partition tables store more magic strings on
  45 the device (e.g. FAT, ZFS, GPT).  The
  46 .B wipefs
  47 command (since v2.31) lists all the offset where a magic strings have been
  48 detected.
  49
  50 When option \fB-a\fR is used, all magic strings that are visible for libblkid are
  51 erased. In this case the
  52 .B wipefs
  53 scans the device again after each modification (erase) until no magic string is found.
  54
  55 Note that by default
  56 .B wipefs
  57 does not erase nested partition tables on non-whole disk devices.
  58 For this the option \fB\-\-force\fR is required.
  59
  60 .SH OPTIONS
  61 .TP
  62 .BR \-a , " \-\-all"
  63 Erase all available signatures.  The set of erased signatures can be
  64 restricted with the \fB\-t\fR option.
  65 .TP
  66 .BR \-b , " \-\-backup"
  67 Create a signature backup to the file $HOME/wipefs-<devname>-<offset>.bak.
  68 For more details see the \fBEXAMPLES\fR section.
  69 .TP
  70 .BR \-f , " \-\-force"
  71 Force erasure, even if the filesystem is mounted.  This is required in
  72 order to erase a partition-table signature on a block device.
  73 .TP
  74 .BR \-h , " \-\-help"
  75 Display help text and exit.
  76 .TP
  77 .BR \-J , " \-\-json"
  78 Use JSON output format.
  79 .TP
  80 .BR \-n , " \-\-noheadings"
  81 Do not print a header line.
  82 .TP
  83 .BR \-O , " \-\-output " \fIlist\fP
  84 Specify which output columns to print.  Use \-\-help to
  85 get a list of all supported columns.
  86 .TP
  87 .BR -n , " \-\-no\-act"
  88 Causes everything to be done except for the write() call.
  89 .TP
  90 .BR \-o , " \-\-offset " \fIoffset\fP
  91 Specify the location (in bytes) of the signature which should be erased from the
  92 device.  The \fIoffset\fR number may include a "0x" prefix; then the number will be
  93 interpreted as a hex value.  It is possible to specify multiple \fB-o\fR options.
  94 .sp
  95 The \fIoffset\fR argument may be followed by the multiplicative
  96 suffixes KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB
  97 (the "iB" is optional, e.g. "K" has the same meaning as "KiB"), or the suffixes
  98 KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB.
  99 .TP
 100 .BR \-p , " \-\-parsable"
 101 Print out in parsable instead of printable format.  Encode all potentially unsafe
 102 characters of a string to the corresponding hex value prefixed by '\\x'.
 103 .TP
 104 .BR \-q , " \-\-quiet"
 105 Suppress any messages after a successful signature wipe.
 106 .TP
 107 .BR \-t , " \-\-types " \fIlist\fP
 108 Limit the set of printed or erased signatures.  More than one type may
 109 be specified in a comma-separated list.  The list or individual types
 110 can be prefixed with 'no' to specify the types on which no action should be
 111 taken.  For more details see mount(8).
 112 .TP
 113 .BR -V , " \-\-version"
 114 Display version information and exit.
 115 .SH EXAMPLES
 116 .TP
 117 .B wipefs /dev/sda*
 118 Prints information about sda and all partitions on sda.
 119 .TP
 120 .B wipefs --all --backup /dev/sdb
 121 Erases all signatures from the device /dev/sdb and creates a signature backup
 122 file ~/wipefs-sdb-<offset>.bak for each signature.
 123 .TP
 124 .B dd if=~/wipefs-sdb-0x00000438.bak of=/dev/sdb seek=$((0x00000438)) bs=1 conv=notrunc
 125 Restores an ext2 signature from the backup file  ~/wipefs-sdb-0x00000438.bak.
 126 .SH AUTHOR
 127 Karel Zak <kzak@redhat.com>
 128 .SH ENVIRONMENT
 129 .IP LIBBLKID_DEBUG=all
 130 enables libblkid debug output.
 131 .SH SEE ALSO
 132 .BR blkid (8),
 133 .BR findfs (8)
 134 .SH AVAILABILITY
 135 The wipefs command is part of the util-linux package and is available from
 136 https://www.kernel.org/pub/linux/utils/util-linux/.