如何用PHP从文件中查找多行？

$fileContent = file_get_contents('filename.txt');

$lines = explode("\n", $fileContent);

$keyword = 'search keyword';
$matchingLines = array();

foreach ($lines as $line) {
    if (strpos($line, $keyword) !== false) {
        $matchingLines[] = $line;
    }
}

foreach ($matchingLines as $matchingLine) {
    echo $matchingLine . "<br>";
}