wipefs

WIPEFS(8)                    System Administration                   WIPEFS(8)

NAME
       wipefs - wipe a signature from a device

SYNOPSIS
       wipefs [options] device...

       wipefs [--backup] -o offset device...

       wipefs [--backup] -a device...

DESCRIPTION
       wipefs  can erase filesystem, raid or partition-table signatures (magic
       strings) from the specified device to make the signatures invisible for
       libblkid.   wipefs  does  not erase the filesystem itself nor any other
       data from the device.

       When used without any options, wipefs lists all visible filesystems and
       the  offsets  of their basic signatures.  The default output is subject
       to change.  So whenever possible, you should avoid using  default  out-
       puts in your scripts.  Always explicitly define expected columns by us-
       ing --output columns-list in environments where a stable output is  re-
       quired.

       wipefs  calls  the BLKRRPART ioctl when it has erased a partition-table
       signature to inform the kernel about the change. The ioctl is called as
       the  last step and when all specified signatures from all specified de-
       vices are already erased.

       Note that some filesystems and some partition tables store  more  magic
       strings  on the device (e.g. FAT, ZFS, GPT).  The wipefs command (since
       v2.31) lists all the offset where a magic strings have been detected.

       When option -a is used, all magic strings that are visible for libblkid
       are  erased.  In this case the wipefs scans the device again after each
       modification (erase) until no magic string is found.

       Note that by default wipefs does not erase nested partition  tables  on
       non-whole disk devices.  For this the option --force is required.

OPTIONS
       -a, --all
              Erase  all  available  signatures.  The set of erased signatures
              can be restricted with the -t option.

       -b, --backup
              Create  a  signature  backup  to  the  file   $HOME/wipefs-<dev-
              name>-<offset>.bak.  For more details see the EXAMPLES section.

       -f, --force
              Force  erasure,  even if the filesystem is mounted.  This is re-
              quired in order to erase a partition-table signature on a  block
              device.

       -h, --help
              Display help text and exit.

       -J, --json
              Use JSON output format.

       -n, --noheadings
              Do not print a header line.

       -O, --output list
              Specify which output columns to print.  Use --help to get a list
              of all supported columns.

       -n, --no-act
              Causes everything to be done except for the write() call.

       -o, --offset offset
              Specify the location (in bytes) of the signature which should be
              erased  from  the  device.  The offset number may include a "0x"
              prefix; then the number will be interpreted as a hex value.   It
              is possible to specify multiple -o options.

              The  offset  argument may be followed by the multiplicative suf-
              fixes KiB (=1024), MiB (=1024*1024), and so  on  for  GiB,  TiB,
              PiB,  EiB,  ZiB  and YiB (the "iB" is optional, e.g. "K" has the
              same  meaning  as  "KiB"),  or  the  suffixes  KB  (=1000),   MB
              (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB.

       -p, --parsable
              Print  out  in parsable instead of printable format.  Encode all
              potentially unsafe characters of a string to  the  corresponding
              hex value prefixed by '\x'.

       -q, --quiet
              Suppress any messages after a successful signature wipe.

       -t, --types list
              Limit  the  set  of printed or erased signatures.  More than one
              type may be specified in a comma-separated list.   The  list  or
              individual  types can be prefixed with 'no' to specify the types
              on which no action  should  be  taken.   For  more  details  see
              mount(8).

       -V, --version
              Display version information and exit.

EXAMPLES
       wipefs /dev/sda*
              Prints information about sda and all partitions on sda.

       wipefs --all --backup /dev/sdb
              Erases  all  signatures  from  the device /dev/sdb and creates a
              signature backup file ~/wipefs-sdb-<offset>.bak for each  signa-
              ture.

       dd if=~/wipefs-sdb-0x00000438.bak of=/dev/sdb seek=$((0x00000438)) bs=1
       conv=notrunc
              Restores an ext2  signature  from  the  backup  file   ~/wipefs-
              sdb-0x00000438.bak.

AUTHOR
       Karel Zak <kzak@redhat.com>

ENVIRONMENT
       LIBBLKID_DEBUG=all
              enables libblkid debug output.

SEE ALSO
       blkid(8), findfs(8)

AVAILABILITY
       The  wipefs  command is part of the util-linux package and is available
       from https://www.kernel.org/pub/linux/utils/util-linux/.

util-linux                       December 2014                       WIPEFS(8)