MANPATH=«/opt/intel_cc_80/man»:$(man -w); export MANPATH

Курить man man.

-w or --path
Don't actually display the man pages, but do print
the location(s) of the files that would be format-
ted or displayed. If no argument is given: display
(on stdout) the list of directories that is
searched by man for man pages. If manpath is a link
to man, then "manpath" is equivalent to "man
--path".

А у тебя man либо жутко древний либо не линуксовый.

Да, старенький. Вот уж не думал :(