wipefs(8)

1WIPEFS(8)                    System Administration                   WIPEFS(8)
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NAME

6       wipefs - wipe a signature from a device
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SYNOPSIS

9       wipefs [options] device...
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11       wipefs [--backup] -o offset device...
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13       wipefs [--backup] -a device...
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DESCRIPTION

16       wipefs  can erase filesystem, raid or partition-table signatures (magic
17       strings) from the specified device to make the signatures invisible for
18       libblkid.   wipefs  does  not erase the filesystem itself nor any other
19       data from the device.
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21       When used without any options, wipefs lists all visible filesystems and
22       the  offsets  of their basic signatures.  The default output is subject
23       to change.  So whenever possible, you should avoid using  default  out‐
24       puts  in  your  scripts.   Always explicitly define expected columns by
25       using --output columns-list in environments where a  stable  output  is
26       required.
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28       wipefs  calls  the BLKRRPART ioctl when it has erased a partition-table
29       signature to inform the kernel about the change. The ioctl is called as
30       the  last  step  and  when  all specified signatures from all specified
31       devices are already erased.
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33       Note that some filesystems and some partition tables store  more  magic
34       strings on the device (e.g., FAT, ZFS, GPT).  The wipefs command (since
35       v2.31) lists all the offset where a magic strings have been detected.
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37       When option -a is used, all magic strings that are visible for libblkid
38       are  erased.  In this case the wipefs scans the device again after each
39       modification (erase) until no magic string is found.
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41       Note that by default wipefs does not erase nested partition  tables  on
42       non-whole disk devices.  For this the option --force is required.
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OPTIONS

46       -a, --all
47              Erase  all  available  signatures.  The set of erased signatures
48              can be restricted with the -t option.
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50       -b, --backup
51              Create  a  signature  backup  to  the  file   $HOME/wipefs-<dev‐
52              name>-<offset>.bak.  For more details see the EXAMPLES section.
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54       -f, --force
55              Force  erasure,  even  if  the  filesystem  is mounted.  This is
56              required in order to erase  a  partition-table  signature  on  a
57              block device.
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59       -h, --help
60              Display help text and exit.
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62       -J, --json
63              Use JSON output format.
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65       -n, --noheadings
66              Do not print a header line.
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68       -O, --output list
69              Specify which output columns to print.  Use --help to get a list
70              of all supported columns.
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72       -n, --no-act
73              Causes everything to be done except for the write() call.
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75       -o, --offset offset
76              Specify the location (in bytes) of the signature which should be
77              erased  from  the  device.  The offset number may include a "0x"
78              prefix; then the number will be interpreted as a hex value.   It
79              is possible to specify multiple -o options.
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81              The  offset  argument may be followed by the multiplicative suf‐
82              fixes KiB (=1024), MiB (=1024*1024), and so  on  for  GiB,  TiB,
83              PiB,  EiB,  ZiB and YiB (the "iB" is optional, e.g., "K" has the
84              same  meaning  as  "KiB"),  or  the  suffixes  KB  (=1000),   MB
85              (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB.
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87       -p, --parsable
88              Print  out  in parsable instead of printable format.  Encode all
89              potentially unsafe characters of a string to  the  corresponding
90              hex value prefixed by '\x'.
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92       -q, --quiet
93              Suppress any messages after a successful signature wipe.
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95       -t, --types list
96              Limit  the  set  of printed or erased signatures.  More than one
97              type may be specified in a comma-separated list.   The  list  or
98              individual  types can be prefixed with 'no' to specify the types
99              on which no action  should  be  taken.   For  more  details  see
100              mount(8).
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102       -V, --version
103              Display version information and exit.
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EXAMPLES

106       wipefs /dev/sda*
107              Prints information about sda and all partitions on sda.
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109       wipefs --all --backup /dev/sdb
110              Erases  all  signatures  from  the device /dev/sdb and creates a
111              signature backup file ~/wipefs-sdb-<offset>.bak for each  signa‐
112              ture.
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114       dd if=~/wipefs-sdb-0x00000438.bak of=/dev/sdb seek=$((0x00000438)) bs=1
115       conv=notrunc
116              Restores an ext2  signature  from  the  backup  file   ~/wipefs-
117              sdb-0x00000438.bak.
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AUTHOR

120       Karel Zak <kzak@redhat.com>
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ENVIRONMENT

123       LIBBLKID_DEBUG=all
124              enables libblkid debug output.
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AVAILABILITY

130       The  wipefs  command is part of the util-linux package and is available
131       from https://www.kernel.org/pub/linux/utils/util-linux/.
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135util-linux                       December 2014                       WIPEFS(8)