blockdev - call block device ioctls from the command line
blockdev [-q] [-v] command
[command...] device [device...]
blockdev --report [device...]
blockdev -h|-V
The utility blockdev allows one to call block device ioctls
from the command line.
- -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.
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.
blockdev was written by Andries E. Brouwer and rewritten by Karel
Zak.
The blockdev command is part of the util-linux package and is
available from https://www.kernel.org/pub/linux/utils/util-linux/.