Linux Commands Examples

A great documentation place for Linux commands

blockdev

call block device ioctls from the command line

Synopsis

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


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examples

1
source 
            

  ssh $host blockdev --getsize64
  $partition
0
source 
            

  blockpart_blockdev=






  for bd in $blockdev; do




  update_blockdev $bd




  blkpart=$(majorminor2blockdev
  $blockmajor $blockminor)




  blockpart_blockdev="$(update_list $bd
  $blockpart_blockdev)"




  done






  blockdev="$blockpart_blockdev"
0
source 
            

  echo "0
  `blockdev --getsize $1` flashbang $1 0" | dmsetup
  create flashbang-dev
0
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  echo "0
  `blockdev --getsize $1` linear $1 0" | dmsetup
  create identity
0
source 
            

  echo 0 `blockdev --getsize /dev/loop0` crypt blowfish 0123456789abcdef0123456789abcdef 0
  /dev/loop0 0 | dmsetup create volume1

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.

availability

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

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 sectorsize in bytes - usually 512.

--getsz

Get size in 512-byte sectors.

--rereadpt

Reread partition table

--setbsz bytes

Set blocksize.

--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.

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