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BLOCKDEV(8)                  System Administration                 BLOCKDEV(8)
NAME
       blockdev - call block device ioctls from the command line
SYNOPSIS
       blockdev [-q] [-v] command [command...] device [device...]
       blockdev --report [device...]
       blockdev -h|-V
DESCRIPTION
       The  utility  blockdev  allows one to call block device ioctls from the
       command line.
OPTIONS
       -q     Be quiet.
       -v     Be verbose.
       --report
              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.
COMMANDS
       It is possible to give multiple devices and multiple commands.
       --flushbufs
              Flush buffers.
       --getalignoff
              Get alignment offset.
       --getbsz
              Print blocksize in bytes.
       --getdiscardzeroes
              Get discard zeroes support status.
       --getfra
              Get filesystem readahead in 512-byte sectors.
       --getiomin
              Get minimum I/O size.
       --getioopt
              Get optimal I/O size.
       --getmaxsect
              Get max sectors per request
       --getpbsz
              Get physical block (sector) size.
       --getra
              Print readahead (in 512-byte sectors).
       --getro
              Get read-only. Print 1 if the device is read-only, 0 otherwise.
       --getsize64
              Print device size in bytes.
       --getsize
              Print  device  size (32-bit!) in sectors. Deprecated in favor of
              the --getsz option.
       --getss
              Print logical sector size in bytes - usually 512.
       --getsz
              Get size in 512-byte sectors.
       --rereadpt
              Reread partition table
       --setbsz bytes
              Set blocksize. Note that the block size is specific to the  cur-
              rent  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).
       --setro
              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.
       --setrw
              Set read-write.
AUTHOR
       blockdev was written by Andries E. Brouwer and rewritten by Karel Zak.
AVAILABILITY
       The blockdev command is part of the util-linux package and is available
       from https://www.kernel.org/pub/linux/utils/util-linux/.
util-linux                        August 2010                      BLOCKDEV(8)