if ($data_choice eq 'l' || $data_choice eq 'L') {
    open my $fh, '<', 'stations.dat'
        or die "Trouble opening stations.dat; is it in same directory as stations.exe? Stopped: $!";
    flock $fh, LOCK_SH
        or die "Trouble getting file lock for stations.dat; is it in use by another program? Stopped: $!";
    @data_lines = <$fh>;
}
else {
    print "\nNow requesting data from the FCC server; this will take a minute or two, even with a high-speed internet connection...\n";
    my $stations_data = get( 'http://www.fcc.gov/fcc-bin/amq?state=&call=&arn=&city=&freq=530&fre2=1700&type=0&facid=&class=&list=4&dist=&dlat2=&mlat2=&slat2=&NS=N&dlon2=&mlon2=&slon2=&EW=W&size=9' );
    open my $fh, '>', 'stations.dat'
        or warn "Trouble opening stations.dat to save new FCC data; is hard drive full? Stopped: $!";
    flock $fh, LOCK_EX
        or die "Trouble getting file lock for stations.dat; is it in use by another program? Stopped: $!";
    print {$fh} $stations_data;
    close $fh
        or warn "Trouble closing file lock for stations.dat";
    @data_lines = split /\n/, $stations_data;
}