NAME¶

blockdev - call block device ioctls from the command line

SYNOPSIS¶

blockdev [options] commands devices
blockdev --report [devices]

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 devices. Note that the partition StartSec is in 512-byte sectors.

COMMANDS¶

--setro

Set read-only.

--setrw

Set read-write.

--getro

Get read-only. Print 1 if the device is read-only, 0 otherwise.

--getss

Print sectorsize in bytes - usually 512.

--getbsz

Print blocksize in bytes.

--setbsz N

Set blocksize to N bytes. 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.

--getsize

Print device size in sectors (BLKGETSIZE). Deprecated in favor of the --getsz option.

--getsize64

Print device size in bytes (BLKGETSIZE64)

--getsz

Get size in 512-byte sectors (BLKGETSIZE64 / 512).

--setra N

Set readahead to N 512-byte sectors.

--getra

Print readahead (in 512-byte sectors).

--setfra N

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

--getfra

Get filesystem readahead.

--flushbufs

Flush buffers.

--rereadpt

Reread partition table.

AUTHOR¶

blockdev was written by Andries E. Brouwer.

AVAILABILITY¶

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