Remove Line using PHP Regexp

How to use regexp to remove line from text file that not containing certain symbol such as equal sign =?

 

$text = preg_replace('~(^|[\r\n]+)(?!.*=).*([\r\n]+|$)~', "\n", trim($text));

PHP:

 

I tried the code something like this:
Input File
---------
abc=123
def=345
php is good
i like it
parm=567
hello2

Php Code:
<?php
$myFile = "report2a.txt";
$fh = fopen($myFile, 'r');
$out="";
while ($data_in = fgets($fh)){
$data_in=preg_replace('~(^|[\r\n]+)(?!.*=).*([\r\n]+|$)~', "\n", trim($data_in));
$out.=$data_in;
}
file_put_contents("report2b.txt",$out);
fclose($fh);
echo "done";
?>

Output generated report2b.txt:
abc=123def=345

parm=567

Look likes carriage return has been truncated or trimmed. Could you fix it to become proper output:
abc=123
def=345
parm=567


Thanks. for your help.

 

$myFile = "report2a.txt";

$lines = file($myFile);
// Remove lines that don't have an equal sign
$lines = array_filter($lines, 'is_valid_line');
// Save
file_put_contents($myFile, implode("\n", $lines));

echo "Done";

function is_valid_line(&$line)
{
	return (strpos($line = trim($line), '=') !== false);
}

PHP:

 

Now okay. Thankx