Updatedb

updatedb is a Unix utility that creates or updates the index database used by the locate command to perform fast filename searches. It does not search file contents; instead it catalogs filenames and paths to enable quick lookups.

The program scans mounted filesystems and builds a database of paths, excluding files and directories according to its configuration. The exact behavior is controlled by a configuration file (commonly updatedb.conf) that specifies which directories to include or prune, which filesystem types to skip, and other indexing rules. Configuration may also influence how often the database is updated and which user permissions apply during indexing.

Databases created by updatedb reside in a system-dependent location. On many systems using the mlocate implementation, the database is stored at /var/lib/mlocate/mlocate.db. Other implementations, such as traditional locate, may use /var/lib/locate/locatedb or similar paths. The locate command reads this database to return fast answers to user queries, typically just searching for matching pathnames.

Running and maintenance: updatedb is often executed automatically by a system administrator via a cron job or a systemd timer to keep the index reasonably up to date. It can also be invoked manually, usually with elevated privileges, for example by running updatedb with sudo. Because it scans large filesystems, the operation can be time consuming and may impact system load while it runs.

Limitations: updatedb indexes only filenames and paths, not file contents, and its results reflect the filesystem as seen at the time of indexing. Changes after an update require a new run to refresh the database.