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.
  42
  43 Note that some filesystems and some partition tables store more magic strings on
  44 the device (e.g. FAT, ZFS, GPT).  The
  45 .B wipefs
  46 command (since v2.31) lists all the offset where a magic strings have been
  47 detected.
  48
  49 When option \fB-a\fR is used, all magic strings that are visible for libblkid are
  50 erased. In this case the
  51 .B wipefs
  52 scans the device again after each modification (erase) until no magic string is found.
  53
  54 Note that by default
  55 .B wipefs
  56 does not erase nested partition tables on non-whole disk devices.
  57 For this the option \fB\-\-force\fR is required.
  58
  59 .SH OPTIONS
  60 .TP
  61 .BR \-a , " \-\-all"
  62 Erase all available signatures.  The set of erased signatures can be
  63 restricted with the \fB\-t\fR option.
  64 .TP
  65 .BR \-b , " \-\-backup"
  66 Create a signature backup to the file $HOME/wipefs-<devname>-<offset>.bak.
  67 For more details see the \fBEXAMPLES\fR section.
  68 .TP
  69 .BR \-f , " \-\-force"
  70 Force erasure, even if the filesystem is mounted.  This is required in
  71 order to erase a partition-table signature on a block device.
  72 .TP
  73 .BR \-h , " \-\-help"
  74 Display help text and exit.
  75 .TP
  76 .BR \-J , " \-\-json"
  77 Use JSON output format.
  78 .TP
  79 .BR \-n , " \-\-noheadings"
  80 Do not print a header line.
  81 .TP
  82 .BR \-O , " \-\-output " \fIlist\fP
  83 Specify which output columns to print.  Use \-\-help to
  84 get a list of all supported columns.
  85 .TP
  86 .BR -n , " \-\-no\-act"
  87 Causes everything to be done except for the write() call.
  88 .TP
  89 .BR \-o , " \-\-offset " \fIoffset\fP
  90 Specify the location (in bytes) of the signature which should be erased from the
  91 device.  The \fIoffset\fR number may include a "0x" prefix; then the number will be
  92 interpreted as a hex value.  It is possible to specify multiple \fB-o\fR options.
  93 .sp
  94 The \fIoffset\fR argument may be followed by the multiplicative
  95 suffixes KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB
  96 (the "iB" is optional, e.g. "K" has the same meaning as "KiB"), or the suffixes
  97 KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB.
  98 .TP
  99 .BR \-p , " \-\-parsable"
 100 Print out in parsable instead of printable format.  Encode all potentially unsafe
 101 characters of a string to the corresponding hex value prefixed by '\\x'.
 102 .TP
 103 .BR \-q , " \-\-quiet"
 104 Suppress any messages after a successful signature wipe.
 105 .TP
 106 .BR \-t , " \-\-types " \fIlist\fP
 107 Limit the set of printed or erased signatures.  More than one type may
 108 be specified in a comma-separated list.  The list or individual types
 109 can be prefixed with 'no' to specify the types on which no action should be
 110 taken.  For more details see mount(8).
 111 .TP
 112 .BR -V , " \-\-version"
 113 Display version information and exit.
 114 .SH EXAMPLES
 115 .TP
 116 .B wipefs /dev/sda*
 117 Prints information about sda and all partitions on sda.
 118 .TP
 119 .B wipefs --all --backup /dev/sdb
 120 Erases all signatures from the device /dev/sdb and creates a signature backup
 121 file ~/wipefs-sdb-<offset>.bak for each signature.
 122 .TP
 123 .B dd if=~/wipefs-sdb-0x00000438.bak of=/dev/sdb seek=$((0x00000438)) bs=1 conv=notrunc
 124 Restores an ext2 signature from the backup file  ~/wipefs-sdb-0x00000438.bak.
 125 .SH AUTHOR
 126 Karel Zak <kzak@redhat.com>
 127 .SH ENVIRONMENT
 128 .IP LIBBLKID_DEBUG=all
 129 enables libblkid debug output.
 130 .SH SEE ALSO
 131 .BR blkid (8),
 132 .BR findfs (8)
 133 .SH AVAILABILITY
 134 The wipefs command is part of the util-linux package and is available from
 135 https://www.kernel.org/pub/linux/utils/util-linux/.