blockdev
call block device ioctls from the command line
Synopsis
blockdev
[-q] [-v] command
[command...] device [device...]
blockdev --report [device...]
add an example, a script, a trick and tips
examples
source
ssh $host blockdev --getsize64
$partition
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"
source
echo "0
`blockdev --getsize $1` flashbang $1 0" | dmsetup
create flashbang-dev
source
echo "0
`blockdev --getsize $1` linear $1 0" | dmsetup
create identity
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.