mandb is used to initialise or manually update index database caches that are usually maintained by man. The caches contain information relevant to the current state of the manual page system and the information stored within them is used by the man_db utilities to enhance their speed and functionality.
When creating or updating an index, mandb will warn of bad ROFF .so requests, bogus manual page filenames and manual pages from which the whatis cannot be parsed.
mandb can be compiled with support for any one of the following database types.
Produce debugging information.
Produce no warnings.
Do not spend time looking for or adding information to the databases regarding stray cats.
Do not spend time checking for deleted manual pages and purging them from the databases.
By default, mandb will try to update any previously created databases. If a database does not exist, it will create it. This option forces mandb to delete previous databases and re-create them from scratch, and implies --no-purge. This may be necessary if a database becomes corrupt or if a new database storage scheme is introduced in the future.
Create user databases only, even with write permissions necessary to create system databases.
Perform correctness checks on manual pages in the hierarchy search path. With this option, mandb will not alter existing databases.
Show the usage message, then exit.
The following warning messages can be emitted during database building.
An attempt to extract whatis line(s) from the given WHATIS PARSING__ section in lexgrog(1) for more information.
man_db configuration file.
A traditional global index database cache.
An alternate or FSSTND compliant global index database cache.