I wanna read some text files in a folder line by line. for example of 1 txt :

Fast and Effective Text Mining Using Linear-time Document Clustering
Bjornar Larsen WORD2 Chinatsu Aone
SRA International AK, Inc.
4300 Fair Lakes Cow-l Fairfax, VA 22033

{bjornar-larsen, WORD1

I wanna remove line that does not contain of words = word, word2, word3, and does not end with dot .

so. from the example, the result will be :

Bjornar Larsen WORD2 Chinatsu Aone
SRA International, Inc.
{bjornar-larsen, WORD1

I am confused, hw to remove the line? it that possible? or can we replace them with a space?

here's the code :

$url = glob($savePath.'*.txt');
foreach ($url as $file => $files) {
    $handle = fopen($files, "r") or die ('can not open file');
    $ori_content= file_get_contents($files);
    foreach(preg_split("/((\r?\n)|(\r\n?))/", $ori_content) as $buffer){
        $pos1 = stripos($buffer, $word1);
        $pos2 = stripos($buffer, $word2);
        $pos3 = stripos($buffer, $word3);
        $last = $str[strlen($buffer)-1];//read the las character
        if (true !== $pos1 OR true !== $pos2 OR true !==$pos3 && $last != '.'){
        //how to remove
        }
    }
}

please help me, thank you so much :)