apropos command is used to search and display a short man page description of a command/program as follows.
apropos [-dalv?V] [-e|-w|-r] [-s list] [-m system[,…]] [-M path] [-L
locale] [-C file] keyword …
Each manual page has a short description available within it and apropos is the specific tool that enables you to search through the description of a manpage for the instances of a specific keyword.
Keyword may be defined as a regular expression. as if (-r) was used, or may contain wildcards (-w), or match the exact keyword (-e). Using these options, it may be necessary to quote the keyword or escape (\) the special characters to stop the shell from interpreting them.
-d, –debug emit debugging messages
-v, –verbose print verbose warning messages
-e, –exact search each keyword for exact match
-r, –regex interpret each keyword as a regex
-w, –wildcard the keyword(s) contain wildcards
-a, –and require all keywords to match
-l, –long do not trim output to terminal width
-C, –config-file=FILE use this user configuration file
-L, –locale=LOCALE define the locale for this search
-m, –systems=SYSTEM use manual pages from other systems
-M, –manpath=PATH set search path for manual pages to PATH
-s, –sections=LIST, –section=LIST
search only these sections (colon-separated)
-?, –help give this help list
–usage give a short usage message
-V, –version print program version
$ apropos adduser