The Getopt::Long docs have a too trivial example of how to run a subroutine by setting an option. Here's what the doc says: 

User-defined subroutines to handle options

       Ultimate control over what should be done when (actually: each 
+time) an option is encountered on the command line can be achieved by
+ designating a reference to a subroutine (or an anonymous subroutine)
+ as the option destination. When GetOptions() encounters the option, 
+it will call the sub-routine with two or three arguments. The first a
+rgument is the name of the option. For a scalar or array destination,
+ the second argument is the value to be stored. For a hash destinatio
+n, the second arguments is the key to the hash, and the third argumen
+t the value to be stored. It is up to the subroutine to store the val
+ue, or do whatever it thinks is appropriate.

       A trivial application of this mechanism is to implement options
+ that are related to each other. For example:

           my $verbose = '';   # option variable with default value (f
+alse)
           GetOptions ('verbose' => \$verbose,
                       'quiet'   => sub { $verbose = 0 });

       Here "--verbose" and "--quiet" control the same variable $verbo
+se, but with opposite values.

       If the subroutine needs to signal an error, it should call die(
+) with the desired error message as its argument. GetOptions() will c
+atch the die(), issue the error message, and record that an error res
+ult must be returned upon completion.

       If the text of the error message starts with an exclamantion ma
+rk "!"  it is interpreted specially by GetOptions(). There is current
+ly one special command implemented: "die("!FINISH")" will cause GetOp
+tions() to stop processing options, as if it encountered a double das
+h "--".

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So, here the doc shows usage with an anonymous subroutine. I'm new to Perl and it would be helpful for me to see usage of predefined subroutines with Getopt::Long. If possible, how do I pass arguments to the subroutine? I haven't been able to find any Perl scripts that use Getopt::Long either. Can you share yours with me, so I can glean the information I need? Thank you.

In reply to Getopt::Long subroutine usage by rockneybot

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