for my $opt ( qw/user_name password input_file/ ) {
    next if ( $opthash{$opt} );
    print "You need to specify a $opt: "
    if ( $opt eq "password" ) { 
        ReadMode( "noecho" );
    else {
        ReadMode( "normal" );
    }
    $opthash{$opt} = ReadLine(0);
    ReadMode( "restore" );
    die "You really should have typed something for $opt\n"
        unless ( $opthash{$opt} );
}  # this input mechanism only needs to be written once