Linux interface to SMART data for hard disks.
Examples
Show identifying information about a device
smartctl -i /dev/sda
Show drive attributes
This shows a bunch of recorded information that is updated over the life of the drive.
smartctl -A /dev/sda
Show the same information with better output showing vendor flags
smartctl -A -f brief /dev/sda
Show all data
smartctl -x /dev/sda