use strict;
use warnings;
use Getopt::Std;
use LWP::UserAgent;

our($opt_p);
getopts('p'); # getopts() not getopt()

print "\nThe value in \$opt_p is ";
print defined($opt_p) ? "'$opt_p'" : "undefined";

my $agent = LWP::UserAgent->new();
($opt_p == 1 ? $agent->env_proxy() : $agent->proxy(http => $opt_p)) if (defined($opt_p));