wipefs man page

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.

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 Examples 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.

-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 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.

Examples

wipefs /dev/sda*

Prints infomation 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.

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/.

Referenced By

blkid(8), btrfs-device(8), cfdisk(8), fdisk(8), mkfs.btrfs(8), sfdisk(8).

December 2014 util-linux System Administration