@techee thank you for the answer. Theoretically speaking, I understood what is happening in terms of shells and paths. In practice, I really don't know where to put my hands to set the path of fortran inside "~/.profile" (honestly, given I am new to this kind programming, I fear a little bit in touching the Terminal). What I can say is that all my university-colleagues who use Mac and Geany are facing my very same issue.