$re = '/.*(FunFehlerButton: Execute).*/';
$str = 'INFO: Device 6: Time 20.11.2015 06:28:00 - [Script] FunFehlerButton: Execute [0031 text]
INFO: Device 0: Time 09.12.2015 03:51:44 - [Replication] FunFehlerButton: Execute
INFO: Device 6: Time 20.11.2015 06:28:00 - FunFehlerButton: Execute';
$subst = "$1";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php