BLOCKDEV(8)

NAME
blockdev - call block device ioctls from the command line

SYNOPSIS
blockdev [-q] [-v] command [command...] device [device...]
blockdev --report [device...]

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

OPTIONS

-V  Print version and exit.

-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.

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 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.

--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 ftp://ftp.kernel.org/pub/linux/utils/util-linux/.