$re = '/^(?!QCNIL|Epic_SNA).+$/m';
$str = 'Epic_IKDH_Appt_Phone_Reminders_20191030.txt
Epic_NAMMI_Appt_Phone_Reminders_20191031.txt
QCNIL-Recall_Phone_Reminders_20191029.txt
Epic_SNA_Appt_No_Show_Reminders_20191029.txt
Epic_IKDH_Appt_Phone_Reminders_20191030.txt
Epic_NAMMI_Appt_Phone_Reminders_20191031.txt
QCNIA-Recall_Phone_Reminders_20191029.txt
Epic_SNB_Appt_No_Show_Reminders_20191029.txt';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
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