man – format and display the on-line manual pages
man [-acdfFhkKtwW] [–path] [-m system] [-p string] [-C config_file] [-M pathlist]
[-P pager] [-B browser] [-H htmlpager] [-S section_list] [section] name …
man formats and displays the on-line manual pages. If you specify section, man only looks in that section of the manual. name is normally the name of the manual page, which is typically the name of a command, function, or file.
The output of man ls command:
The apropos command can be used before man in order to find all the man pages for commands which contain a certain word.
The same purpose has whatis command. whatis – searches the whatis database for complete words. Example of using whatis command:
To review all man pages related to the command use -a option. For example: man nano -a