blockdev8
Call block device ioctls from the command line
Usage
blockdev [-q]
[-v]
command
[command ...]
device
[device ...]
blockdev --report
[device ...]
blockdev {-h | -V}
Overview
The utility blockdev allows one to call block device ioctls from the command line.
Options
-
-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 -
Display version and exit.
Commands
It is possible to give multiple devices and multiple commands.
-
--flushbufs -
Flush buffers.
-
--getalignoff -
Get alignment offset.
-
--getbsz -
Print the blocksize in bytes. This size does not describe device topology. It’s the size used internally by the kernel and it may be modified (for example) by filesystem driver on mount.
-
--getdiscardzeroes -
Get discard zeroes support status.
-
--getdiskseq -
Get disk sequence number.
-
--getzonesz -
Get zone size in 512-byte sectors.
-
--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
--getszoption.
-
--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
blockdevhas the device open, and is lost onceblockdevexits.
-
--setfra sectors -
Set filesystem readahead (same as
--setraon 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, a filesystem already mounted in read-write mode will not be affected. The change applies after remount.
-
--setrw -
Set read-write.
Releases
13 releases since Debian 3.0 (Woody); the text changed 10 times.
--getalignoff since Debian 7 (Wheezy);
--getbsz since Debian 5.0 (Lenny);
--getdiscardzeroes since Debian 7 (Wheezy);
--getdiskseq since Debian 13 (Trixie);
--getfra since Debian 5.0 (Lenny);
--getiomin since Debian 7 (Wheezy);
--getioopt since Debian 7 (Wheezy);
--getmaxsect since Debian 7 (Wheezy);
--getpbsz since Debian 7 (Wheezy);
--getsize64 since Debian 5.0 (Lenny);
--getsz since Debian 5.0 (Lenny);
--getzonesz since Debian 13 (Trixie);
--help since Debian 10 (Buster);
--report since Debian 5.0 (Lenny);
--setbsz since Debian 7 (Wheezy);
--setfra since Debian 7 (Wheezy);
--setra since Debian 7 (Wheezy);
--version since Debian 10 (Buster);
-h since Debian 10 (Buster).