#!/usr/bin/perl -w
use strict;
use warnings;

sub show {
    for my $var (@_) {
        print "$var: ".(defined $ENV{$var} ? $ENV{$var} : '')."\n";
    }
}
show(qw(dir work_dir prog_path prog_dir prog conf conf_file_var PATH PERL5LIB));
show(qw(hello world));
print "$_\n" for @ARGV;