BLOCKDEV(8)                 System Administration                BLOCKDEV(8)

NAME         top

       blockdev - call block device ioctls from the command line

SYNOPSIS         top

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

DESCRIPTION         top

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

OPTIONS         top

       -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         top

       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
              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).

       --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         top

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

AVAILABILITY         top

       The blockdev command is part of the util-linux package and is
       available from https://www.kernel.org/pub/linux/utils/util-linux/.

COLOPHON         top

       This page is part of the util-linux (a random collection of Linux
       utilities) project.  Information about the project can be found at 
       ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩.  If you have a
       bug report for this manual page, send it to
       util-linux@vger.kernel.org.  This page was obtained from the
       project's upstream Git repository
       ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
       2018-02-02.  (At that time, the date of the most recent commit that
       was found in the repository was 2018-02-01.)  If you discover any
       rendering problems in this HTML version of the page, or you believe
       there is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

util-linux                       August 2010                     BLOCKDEV(8)

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