fwrite writing from beginning without removing

Question

I am using PHP and fwrite code, but I want every write position to start from the beginning of the file without erasing it\'s content. I am using this code but it is writing

Answer 1

$file = 'aaaa.txt';
$tmp = file_get_contents($file);
$tmp = 'text'.$tmp;
$tmp = file_put_contents($file, $tmp);
echo ($tmp != false)? 'OK': '!OK';