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 outputs in
       your scripts.  Always explicitly define expected columns by using
       --output columns-list in environments where a stable output is required.

       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
       devices are already erased.  This feature can be used to wipe content on
       partitions devices as well as partition table on a disk device, for
       example by wipefs -a /dev/sdc1 /dev/sdc2 /dev/sdc.

       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-<devname>-<offset>.bak.  For more details see the
              EXAMPLE section.

       -f, --force
              Force erasure, even if the filesystem is mounted.  This is
              required 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.

       --lock[=mode]
              Use exclusive BSD lock for device or file it operates.  The
              optional argument mode can be yes, no (or 1 and 0) or nonblock.
              If the mode argument is omitted, it defaults to "yes".  This
              option overwrites environment variable $LOCK_BLOCK_DEVICE.  The
              default is not to use any lock at all, but it's recommended to
              avoid collisions with udevd or other tools.

       -i, --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 suffixes
              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.

ENVIRONMENT
       LIBBLKID_DEBUG=all
              enables libblkid debug output.

       LOCK_BLOCK_DEVICE=<mode>
              use exclusive BSD lock.  The mode is "1" or "0".  See --lock for
              more details.

EXAMPLE
       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
              signature.

       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.

AUTHORS
       Karel Zak <kzak@redhat.com>

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)