What command shows SMART self-test history?

• A. sudo smartctl -l selftest /dev/sdX
• B. sudo smartctl -l error /dev/sdX
• C. sudo smartctl -a /dev/sdX
• D. sudo smartctl -t long /dev/sdX

Answer: (A)

SMART self-test history lives in the self-test log, which records each self-test the drive has run, including the type, start time, and result. To see that history, use the command that specifically reads this log: sudo smartctl -l selftest /dev/sdX. This prints the self-test log for the device, giving you a history of what tests were executed and their outcomes. Other options serve different purposes: -l error shows the error log, not the self-test history; -a displays all SMART information, including health and attributes, but not a focused past-test record; -t long starts a new self-test rather than showing past tests. So the command that directly reveals the self-test history is the one that queries the self-test log.