Which command updates the locate database used by the locate utility?

• A. find
• B. updatedb
• C. locate
• D. rpm -qa

Answer: (B)

locate searches a prebuilt index of file paths, which makes it much faster than scanning the filesystem every time. That index is created and updated by the updatedb command. updatedb scans the filesystem (respecting the configuration in /etc/updatedb.conf and related settings) and writes the results to the database file used by locate (commonly in /var/lib/mlocate or a similar path depending on the implementation). Once the database exists and is up to date, locate can quickly return matches for your query.

If you run updatedb, you refresh the index to reflect new or removed files, so subsequent locate queries reflect the current state. On many systems, this updating happens automatically via cron or a timer, keeping the database reasonably current.

The other options don’t fit because: find performs a live traversal of the filesystem each time you search; locate itself is the search tool that queries the database, not the updater; and rpm -qa lists installed packages, not files on disk.