blockdev – Call the Block Device Control Program from the Command Line

The blockdev command is a Linux utility that is used to call the block device control program from the command line. This command is used to get or set various parameters of block devices, such as their size, read-only status, and more.

Overview

The blockdev command can be used to perform a variety of tasks related to block devices. Some of the most common uses of this command include:

• Getting information about block devices, such as their size, sector size, and read-only status
• Setting the read-only status of a block device
• Flushing the buffer cache for a block device
• Resizing a block device

Here are some examples of how to use the blockdev command:

• To get information about a block device, such as its size and sector size, use the following command:

  $ blockdev --getsize64 /dev/sda
  1000204886016
  $ blockdev --getss /dev/sda
  512
  

• To set the read-only status of a block device, use the following command:

  $ blockdev --setro /dev/sda
  

• To flush the buffer cache for a block device, use the following command:

  $ blockdev --flushbufs /dev/sda
  

• To resize a block device, use the following command:

  $ blockdev --setsize /dev/sda 500G
  

Options

The blockdev command has a variety of options that can be used to customize its behavior. Here is a table of all available options:

Troubleshooting Tips

Here are some troubleshooting tips for common issues that may arise when using the blockdev command:

• If you are trying to set the size of a block device and the command fails with an error message, make sure that the new size is valid for the device. For example, you cannot set the size of a block device to be larger than its physical capacity.
• If you are trying to set the read-only status of a block device and the command fails with an error message, make sure that you have the necessary permissions to modify the device. You may need to run the command as root or with sudo.

Notes

• The blockdev command is typically used by system administrators and advanced users who need to manage block devices on Linux systems.
• This command should be used with caution, as modifying the parameters of a block device can have unintended consequences. Always make sure that you understand the implications of the command you are running before executing it.