use Getopt::Std;

my $Usage = "Usage: $0 -u user -p passwd -h host:port\n"
# or "$0 -f foo -b bar -z baz" for some other script

# hash to hold option flags, default values:
my %opt = ( u => 'me',
            p => 'secret',
            h => 'localhost:80' );
my $opts = join '', keys %opt;

die $Usage 
    unless ( getopt( $opts, \%opt ) and
             $opt{u} =~ /\w/ and $opt{p} =~ /\S/ and 
             $opt{h} =~ /\w:\d+$/ );

# adjust or skip the sanity checks as you please