mandb(8) — Linux manual page


MANDB(8)                     Manual pager utils                     MANDB(8)

NAME         top

       mandb - create or update the manual page index caches

SYNOPSIS         top

       mandb [-dqsucpt?V] [-C file] [manpath]
       mandb [-dqsut] [-C file] -f filename ...

DESCRIPTION         top

       mandb is used to initialise or manually update index database caches.
       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.

       Supplying mandb with an optional colon-delimited path will override
       the internal system manual page hierarchy search path, determined
       from information found within the man-db configuration file.


       mandb can be compiled with support for any one of the following
       database types.

       Name          Type                   Async   Filename
       Berkeley db   Binary tree            Yes
       GNU gdbm      Hashed                 Yes     index.db
       UNIX ndbm     Hashed                 No      index.(dir|pag)

       Those database types that support asynchronous updates provide
       enhanced speed at the cost of possible corruption in the event of
       unusual termination.  In an unusual case where this has occurred, it
       may be necessary to rerun mandb with the -c option to re-create the
       databases from scratch.

OPTIONS         top

       -d, --debug
              Print debugging information.

       -q, --quiet
              Produce no warnings.

       -s, --no-straycats
              Do not spend time looking for or adding information to the
              databases regarding stray cats.

       -p, --no-purge
              Do not spend time checking for deleted manual pages and
              purging them from the databases.

       -c, --create
              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.

       -u, --user-db
              Create user databases only, even with write permissions
              necessary to create system databases.

       -t, --test
              Perform correctness checks on manual pages in the hierarchy
              search path.  With this option, mandb will not alter existing

       -f, --filename
              Update only the entries for the given filename.  This option
              is not for general use; it is used internally by man when it
              has been compiled with the MAN_DB_UPDATES option and finds
              that a page is out of date.  It implies -p and disables -c and

       -C file, --config-file=file
              Use this user configuration file rather than the default of

       -?, --help
              Show the usage message, then exit.

              Print a short usage message and exit.

       -V, --version
              Show the version, then exit.

EXIT STATUS         top

       0      Successful program execution.

       1      Usage, syntax, or configuration file error.

       2      Operational error.

       3      A child process failed.

DIAGNOSTICS         top

       The following warning messages can be emitted during database

       <filename>: whatis parse for page(sec) failed
              An attempt to extract whatis line(s) from the given <filename>
              failed.  This is usually due to a poorly written manual page,
              but if many such messages are emitted it is likely that the
              system contains non-standard manual pages which are
              incompatible with the man-db whatis parser.  See the WHATIS
              PARSING section in lexgrog(1) for more information.

       <filename>: is a dangling symlink
              <filename> does not exist but is referenced by a symbolic
              link.  Further diagnostics are usually emitted to identify the
              <filename> of the offending link.

       <filename>: bad symlink or ROFF `.so' request
              <filename> is either a symbolic link to, or contains a ROFF
              include request to, a non existent file.

       <filename>: ignoring bogus filename
              The <filename> may or may not be a valid manual page but its
              name is invalid.  This is usually due to a manual page with
              sectional extension <x> being put in manual page section <y>.

       <filename_mask>: competing extensions
              The wildcard <filename_mask> is not unique.  This is usually
              caused by the existence of both a compressed and uncompressed
              version of the same manual page.  All but the most recent are

FILES         top

              man-db configuration file.

              An FHS compliant global index database cache.

       Older locations for the database cache included:

              A traditional global index database cache.

              An alternate or FSSTND compliant global index database cache.

SEE ALSO         top

       lexgrog(1), man(1), manpath(5), catman(8)

       The WHATIS PARSING section formerly in this manual page is now part
       of lexgrog(1).

AUTHOR         top

       Wilf. (
       Fabrizio Polacco (
       Colin Watson (

BUGS         top

COLOPHON         top

       This page is part of the man-db (manual pager suite) project.
       Information about the project can be found at 
       ⟨⟩.  If you have a bug report for this
       manual page, send it to  This page was ob‐
       tained from the project's upstream Git repository
       ⟨⟩ on 2020-11-01.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-09-13.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or im‐
       provements to the information in this COLOPHON (which is not part of
       the original manual page), send a mail to

2.8.4                            2018-07-27                         MANDB(8)

Pages that refer to this page: apropos(1)lexgrog(1)man(1)whatis(1)groff_man(7)groff_man_style(7)man(7)catman(8)