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 [ \-ahnpqtV ]
  10 .RB [ \-o
  11 .IR offset ]
  12 .IR device ...
  13 .SH DESCRIPTION
  14 .B wipefs
  15 can erase filesystem, raid or partition-table signatures (magic strings) from
  16 the specified
  17 .I device
  18 to make the signatures invisible for libblkid.
  19
  20 .B wipefs
  21 does not erase the filesystem itself nor any other data from the device.
  22 When used without any options, \fBwipefs\fR lists all visible filesystems
  23 and the offsets of their basic signatures.
  24
  25 .B wipefs
  26 calls the BLKRRPART ioctl when it has erased a partition-table signature
  27 to inform the kernel about the change.
  28
  29 Note that some filesystems and some partition tables store more magic strings on
  30 the device.  The
  31 .B wipefs
  32 command lists only the first offset where a magic string has been detected.  The device
  33 is not scanned for additional magic strings for the same filesystem.  It is possible
  34 that after a \fBwipefs -o \fIoffset\fR the same filesystem or partition
  35 table will still be visible because of another magic string on another offset. The
  36 option \fB\-\-no\-act\fR is also affected by this behavior and only the first
  37 magic string for the filesystem is reported.
  38
  39 When option \fB-a\fR is used, all magic strings that are visible for libblkid are
  40 erased. In this case the
  41 .B wipefs
  42 scans the device again after each modification (erase) until no magic string is found.
  43
  44 Note that by default
  45 .B wipefs
  46 does not erase nested partition tables on non-whole disk devices.
  47 For this the option \fB\-\-force\fR is required.
  48
  49 .SH OPTIONS
  50 .TP
  51 .BR \-a , " \-\-all"
  52 Erase all available signatures.  The set of erased signatures can be
  53 restricted with the \fB\-t\fR option.
  54 .TP
  55 .BR \-b , " \-\-backup"
  56 Create a signature backup to the file $HOME/wipefs-<devname>-<offset>.bak.
  57 For more details see the \fBEXAMPLES\fR section.
  58 .TP
  59 .BR \-f , " \-\-force"
  60 Force erasure, even if the filesystem is mounted.  This is required in
  61 order to erase a partition-table signature on a block device.
  62 .TP
  63 .BR \-h , " \-\-help"
  64 Display help text and exit.
  65 .TP
  66 .BR -n , " \-\-no\-act"
  67 Causes everything to be done except for the write() call.
  68 .TP
  69 .BR \-o , " \-\-offset " \fIoffset\fP
  70 Specify the location (in bytes) of the signature which should be erased from the
  71 device.  The \fIoffset\fR number may include a "0x" prefix; then the number will be
  72 interpreted as a hex value.  It is possible to specify multiple \fB-o\fR options.
  73 .sp
  74 The \fIoffset\fR argument may be followed by the multiplicative
  75 suffixes KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB
  76 (the "iB" is optional, e.g. "K" has the same meaning as "KiB"), or the suffixes
  77 KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB.
  78 .TP
  79 .BR \-p , " \-\-parsable"
  80 Print out in parsable instead of printable format.  Encode all potentially unsafe
  81 characters of a string to the corresponding hex value prefixed by '\\x'.
  82 .TP
  83 .BR \-q , " \-\-quiet"
  84 Suppress any messages after a successful signature wipe.
  85 .TP
  86 .BR \-t , " \-\-types " \fIlist\fP
  87 Limit the set of printed or erased signatures.  More than one type may
  88 be specified in a comma-separated list.  The list or individual types
  89 can be prefixed with 'no' to specify the types on which no action should be
  90 taken.  For more details see mount(8).
  91 .TP
  92 .BR -V , " \-\-version"
  93 Display version information and exit.
  94 .SH EXAMPLES
  95 .TP
  96 .BR "wipefs --all --backup /dev/sdb"
  97 Erases all signatures from the device /dev/sdb and creates a signature backup
  98 file ~/wipefs-sdb-<offset>.bak for each signature.
  99 .TP
 100 .BR "dd if=~/wipefs-sdb-0x00000438.bak of=/dev/sdb seek=$((0x00000438)) bs=1 conv=notrunc"
 101 Restores an ext2 signature from the backup file  ~/wipefs-sdb-0x00000438.bak.
 102 .SH AUTHOR
 103 Karel Zak <kzak@redhat.com>
 104 .SH ENVIRONMENT
 105 .IP LIBBLKID_DEBUG=all
 106 enables libblkid debug output.
 107 .SH SEE ALSO
 108 .BR blkid (8),
 109 .BR findfs (8)
 110 .SH AVAILABILITY
 111 The wipefs command is part of the util-linux package and is available from
 112 https://www.kernel.org/pub/linux/utils/util-linux/.