[ Thanks to Kevin
Reichard for this link. ]
“In the abstract, this “ignore command-line options” approach is
appealing–after all, what’s the point of festooning our programs
with all those widgets, except to give the user complete control
over the program? But once we move from fuzzy abstracts like “all
GUI applications” to specific programs with real needs, the scene
changes radically, and before you can say “user request” you’re
faced with a slew of minor issues, some of which can best be solved
with good old-fashioned command-line processing.”
“To no one’s surprise, there are several ways to tiptoe through
command-line options under Linux. You can manually process the
argc/argv variable passed to your main() function, if you like, but
that’s a pain, it’s another opportunity to add obscure bugs to your
program, and it can lead to code maintenance hassles when you
(inevitably) add new features to your program. A more
programmer-friendly approach is to use Linux’s getopt_long()
function, which is what I did in this installment of Hello Universe
to give the user some control over the font and colors the program
uses.”
“There are essentially two kinds of options you need to worry
about, and options can either take an argument (as opposed to
causing one) or not, for a total of four combinations. I can’t
begin to provide a comprehensive treatment of command line
processing here, so I’ll present just a basic technique that
requires an argument for each option, but lets you use either a
single dash and letter (“-h”) or a double dash and a complete word
(“–help”) for the options.”