manpath - format of the /etc/manpath.config file
The manpath configuration file is used by the manual page utilities to assess users' manpaths at run time, to indicate which manual page hierarchies (manpaths) are to be treated as system hierarchies and to assign them directories to be used for storing cat files.
If the environment variable $MANPATH is already set, the information contained within /etc/manpath.config will not override it.
By default, man-db examines the user's $PATH. For each path_element found there, it adds manpath_element to the search path.
If there is no MANPATH_MAP line in the configuration file for a given path_element, then it adds all of path_element/../man, path_element/man, path_element/../share/man, and path_element/share/man that exist as directories to the search path.
It then adds any MANDATORY_MANPATH entries from the configuration file to the search path.
Finally, if the --systems option is used or the $SYSTEM environment variable is set, then that should consist of a sequence of operating system names separated by commas or colons. This acts as a template, expanding the search path once more to allow access to other operating systems' manual pages: for each system name, man-db looks for that name as a subdirectory of each entry in the search path, and adds it to the final search path if it exists. A system name of man inserts the normal search path without subdirectories. For example, if the search path would otherwise have been /usr/share/man:/usr/local/man, and $SYSTEM is set to newOS:man, then the final search path will be /usr/share/man/newOS:/usr/share/man:/usr/local/man/newOS:/usr/local/man.
The $MANPATH environment variable overrides man-db's default manual page search paths. Most users should not need to set it. Its syntax is similar to the $PATH environment variable: it consists of a sequence of directory names separated by colons. It overrides the default search path described above.
If the value of $MANPATH starts with a colon, then the default search path is added at its start. If the value of $MANPATH ends with a colon, then the default search path is added at its end. If the value of $MANPATH contains a double colon (::), then the default search path is inserted in the middle of the value, between the two colons.
The following field types are currently recognised:
Blank lines or those beginning with a # will be treated as comments and ignored.
Lines of this form indicate manpaths that every automatically generated $MANPATH should contain. This will typically include /usr/man.
Lines of this form set up $PATH to $MANPATH mappings. For each path_element found in the user's $PATH, manpath_element will be added to the $MANPATH.
Lines of this form indicate which manpaths are to be treated as system manpaths, and optionally where their cat files should be stored. This field type is particularly important if man is a setuid program, as (when in the system configuration file /etc/manpath.config rather than the per-user configuration file .manpath) it indicates which manual page hierarchies to access as the setuid user and which as the invoking user.
The system manual page hierarchies are usually those stored under /usr such as /usr/man, /usr/local/man and /usr/X11R6/man.
If cat pages from a particular manpath_element are not to be stored or are to be stored in the traditional location, catpath_element may be omitted.
Traditional cat placement would be impossible for read only mounted manual page hierarchies and because of this it is possible to specify any valid directory hierarchy for their storage. To observe the Linux FSSTND the keyword FSSTND can be used in place of an actual directory.
Unfortunately, it is necessary to specify all system man tree paths, including alternate operating system paths such as /usr/man/sun and any NLS locale paths such as /usr/man/de_DE.88591.
As the information is parsed line by line in the order written, it is necessary for any manpath that is a sub-hierarchy of another hierarchy to be listed first, otherwise an incorrect match will be made. An example is that /usr/man/de_DE.88591 must come before /usr/man.
Lines of this form define miscellaneous configuration variables; see the default configuration file for those variables used by the manual pager utilities. They include default paths to various programs (such as grep and tbl), and default sets of arguments to those programs.
Lines of this form define the order in which manual sections should be searched. If there are no SECTION directives in the configuration file, the default is:
SECTION 1 n l 8 3 0 2 5 4 9 6 7
If multiple SECTION directives are given, their section lists will be concatenated.
If a particular extension is not in this list (say, 1mh) it will be displayed with the rest of the section it belongs to. The effect of this is that you only need to explicitly list extensions if you want to force a particular order. Sections with extensions should usually be adjacent to their main section (e.g. "1 1mh 8 ...").
SECTIONS is accepted as an alternative name for this directive.
If the terminal width is less than width, cat pages will not be created (if missing) or displayed. The default is 80.
If the terminal width is greater than width, cat pages will not be created (if missing) or displayed. The default is 80.
If width is non-zero, cat pages will always be formatted for a terminal of the given width, regardless of the width of the terminal actually being used. This should generally be within the range set by MINCATWIDTH and MAXCATWIDTH.
This flag prevents man(1) from creating cat pages automatically.
Unless the rules above are followed and observed precisely, the manual pager utilities will not function as desired. The rules are overly complicated.
https://gitlab.com/cjwatson/man-db/-/issues
https://savannah.nongnu.org/bugs/?group=man-db