$re = '/^([^\n]*TenGigE[^\n]*)(?:(?!TenGigE|carrier-delay).)*([^\n]*carrier-delay[^\n]*)/sm';
$str = 'interface TenGigE0/0/0/8
bundle id 221 mode active
lacp period short
lacp period short receive 100
lacp period short transmit 100
carrier-delay up 100 down 100
interface TenGigE0/0/0/7
shutdown
!
interface TenGigE0/0/0/8
bundle id 221 mode active
lacp period short
lacp period short receive 100
lacp period short transmit 100
carrier-delay up 100 down 100
load-interval 30
frequency synchronization
!
transceiver permit pid all
!
interface TenGigE0/0/0/9
mtu 9216
frequency synchronization
!
transceiver permit pid all
!
interface TenGigE0/0/0/10
bundle id 237 mode active
lacp period short
lacp period short receive 100
lacp period short transmit 100
carrier-delay up 120000 down 150
load-interval 30
frequency synchronization';
preg_match_all($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