"my" variable $FH masks earlier declaration in same scope at C:\Users\Peter\Delme~~\PerlScratch\noname1.pl line 36.
readline() on unopened filehandle FH at C:\Users\Peter\Delme~~\PerlScratch\noname1.pl line 38.
<tr>
<td>(0)</td>
</tr>

##</code><code>##

use strict;
use warnings;
use Fcntl;
use POSIX qw(setsid :errno_h :fcntl_h);

File_Data();

sub File_Data {
    my $path = "fd_search.txt";
    my $create = !sysopen(my $inFile, $path, O_RDONLY);
    my $write;
    my @data;

    if (not $create) {
        @data = <$inFile>;
        $write = !@data;
        close $inFile;
    }

    if ($write || $create) {
        if ($create) {
            sysopen(my $outFile, $path, O_CREAT)
                or die "Create $path failed: $!";
            close $outFile;
        }

        sysopen(my $outFile, $path, O_WRONLY) or die "Create $path failed: $!";
        print $outFile "one two three";
        close $outFile;

        sysopen(my $inFile, $path, O_RDONLY) or die "Reopen $path failed: $!";
        @data = <$inFile>;
    }

    print "<tr>\n";
    print "<td>(0)@data</td>\n";
    print "</tr>\n";
}