bionic (8) blockdev.8.gz

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 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

       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/.