$re = '/([^\.]*\.){2}(?<All>.*)/';
$str = ' TMS_KEP.Male_RTU2.Male_PRM1_GL_OUT
TMS_KEP.Male_RTU2.Male_PRM1_PS_IN
TMS_KEP.Female_RTU2.Female_WC8_RL_OUT
TMS_KEP.Male_RTU1.Male_WC3_FS_OUT
TMS_KEP.Male_RTU1.Male_WC5_FS_OUT';
preg_match_all($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