wipefs - wipe a signature from a device
wipefs [options] device...
wipefs [--backup] -o offset
device...
wipefs [--backup] -a device...
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.
- -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
$LOCK_BLOCK_DEVICE. The default is not to use any lock at all, but
it's recommended to avoid collisions with udevd or other tools.
- -i, --noheadings
- Do not print a header line.
- -O, --output list
- Specify which output columns to print. Use --help to get a list of all
supported columns.
- -n, --no-act
- Causes everything to be done except for the write() call.
- -o, --offset offset
- Specify the location (in bytes) of the signature which should be erased
from the device. The offset number may include a "0x"
prefix; then the number will be interpreted as a hex value. It is possible
to specify multiple -o options.
The offset argument may be followed by the
multiplicative suffixes KiB (=1024), MiB (=1024*1024), and so on for
GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is optional, e.g.,
"K" has the same meaning as "KiB"), or the suffixes
KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and
YB.
- -p, --parsable
- Print out in parsable instead of printable format. Encode all potentially
unsafe characters of a string to the corresponding hex value prefixed by
'\x'.
- -q, --quiet
- Suppress any messages after a successful signature wipe.
- -t, --types list
- Limit the set of printed or erased signatures. More than one type may be
specified in a comma-separated list. The list or individual types can be
prefixed with 'no' to specify the types on which no action should be
taken. For more details see mount(8).
- -V, --version
- Display version information and exit.
- LIBBLKID_DEBUG=all
- enables libblkid debug output.
- LOCK_BLOCK_DEVICE=<mode>
- use exclusive BSD lock. The mode is "1" or "0". See
--lock for more details.
- wipefs /dev/sda*
- Prints information about sda and all partitions on sda.
- wipefs --all --backup /dev/sdb
- Erases all signatures from the device /dev/sdb and creates a signature
backup file ~/wipefs-sdb-<offset>.bak for each signature.
- dd if=~/wipefs-sdb-0x00000438.bak of=/dev/sdb seek=$((0x00000438)) bs=1
conv=notrunc
- Restores an ext2 signature from the backup file
~/wipefs-sdb-0x00000438.bak.
Karel Zak <kzak@redhat.com>
The wipefs command is part of the util-linux package and is available from
https://www.kernel.org/pub/linux/utils/util-linux/.