sub get_log_data {
    open my $logfile, '<', 'logfile' or die "open on logfile: $!";
    my @data_lines;
    while (<$logfile>) {
        next unless ( /fileid/ .. /^-{5}/ ); # range operator!
        if (/specificdata/) {
            push @data_lines, $_;
        }
    }
    close $logfile;
    die 'could not find specificdata in logfile' unless (@data_lines);
    return join q{}, @data_lines;
}