Ooops, missed the mention of getopts.pl. The methods below still work ... the file begins with the following text. Note that Perl5 has been around since 1994 or thereabouts. Using Perl4 code is kinda like using a telephone with a crank which rings a bell to get the operator's attention.

# This library is no longer being maintained, and is included for back
+ward
# compatibility with Perl 4 programs which may require it.
[download]

Your program has a use XXX line for some options module which provides that Getopts(). You can use perldoc Module::Name in a terminal window, or browse to CPAN.org and search for the module name, or you can google the name, or perhaps your IDE will show you the documentation.

Read it.

Come back here if there's anything it doesn't explain.