NAME
blockdev - call block device ioctls from the command lineSYNOPSIS
blockdev [-q] [-v] command [command...] device [ device...]DESCRIPTION
The utility blockdev allows one to call block device ioctls from the command line.OPTIONS
-qBe quiet.
Be verbose.
Print a report for the specified device. It is
possible to give multiple devices. If none is given, all devices which appear
in /proc/partitions are shown. Note that the partition StartSec is in
512-byte sectors.
Display help text and exit.
Print version and exit.
COMMANDS
It is possible to give multiple devices and multiple commands.Flush buffers.
Get alignment offset.
Print the blocksize in bytes. This size does
not describe device topology. It’s the size used internally by the
kernel and it may be modified (for example) by filesystem driver on
mount.
Get discard zeroes support status.
Get filesystem readahead in 512-byte
sectors.
Get minimum I/O size.
Get optimal I/O size.
Get max sectors per request.
Get physical block (sector) size.
Print readahead (in 512-byte sectors).
Get read-only. Print 1 if the device is
read-only, 0 otherwise.
Print device size in bytes.
Print device size (32-bit!) in sectors.
Deprecated in favor of the --getsz option.
Print logical sector size in bytes - usually
512.
Get size in 512-byte sectors.
Reread partition table
Set blocksize. Note that the block size is
specific to the current file descriptor opening the block device, so the
change of block size only persists for as long as blockdev has the
device open, and is lost once blockdev exits.
Set filesystem readahead (same as
--setra on 2.6 kernels).
Set readahead (in 512-byte sectors).
Set read-only. The currently active access to
the device may not be affected by the change. For example, a filesystem
already mounted in read-write mode will not be affected. The change applies
after remount.
Set read-write.
AUTHORS
blockdev was written by Andries E. Brouwer and rewritten by Karel Zak.REPORTING BUGS
For bug reports, use the issue tracker at <https://github.com/util-linux/util-linux/issues>.AVAILABILITY
The blockdev command is part of the util-linux package which can be downloaded from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>.2022-05-11 | util-linux 2.38.1 |