Provided by: util-linux_2.36.1-8ubuntu1_amd64 bug


       blockdev - call block device ioctls from the command line


       blockdev [-q] [-v] command [command...] device [device...]
       blockdev --report [device...]
       blockdev -h|-V


       The utility blockdev allows one to call block device ioctls from the command line.


       -q     Be quiet.

       -v     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.

       -h, --help
              Display help text and exit.

       -V, --version
              Print version and exit.


       It is possible to give multiple devices and multiple commands.

              Flush buffers.

              Get alignment offset.

              Print  blocksize in bytes.  This size does not describe device topology.  It's size
              used internally by kernel and it maybe 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

       --setbsz bytes
              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.

       --setfra sectors
              Set filesystem readahead (same like --setra on 2.6 kernels).

       --setra sectors
              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 filesystem already mounted  in  read-write  mode  will  not  be
              affected. The change applies after remount.

              Set read-write.


       blockdev was written by Andries E. Brouwer and rewritten by Karel Zak.


       The   blockdev   command  is  part  of  the  util-linux  package  and  is  available  from