Apropos shows which manual sections contain instances of any of the given keywords in their title. Each word is considered separately and
case of letters is ignored. Words which are part of other words are considered; thus, when looking for compile, apropos will find all
instances of `compiler' also. Try
If the line starts `name(section) ...' you can do `man section name' to get the documentation for it. Try `apropos format' and then `man
3s printf' to get the manual on the subroutine printf.
Apropos is actually just the -k option to the man(1) command.