wipefs(8) - phpMan

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(3) 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(2) 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(3) debug output.

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

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 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 AT redhat.com>