$re = '/^(?<id>[a-zA-Z0-9]{8})\s+(?<conn>\w+=\S+)\s+(?<op>\w+=\S+)\s+(?<cmd>.*?)\s*(?<rest>\w+=.*)?$/m';
$str = '620da112 conn=2871219 op=1 SRCH attr=extensionAttribute6
620da112 conn=2871220 fd=60 ACCEPT from IP=10.17.28.159:35708 (IP=0.0.0.0:19000)
620da112 conn=2871219 op=1 SEARCH RESULT tag=101 err=0 nentries=1 text=
620da112 conn=2871219 op=2 UNBIND
620da112 conn=2871219 fd=52 closed
620da112 conn=2871220 fd=60 TLS established tls_ssf=256 ssf=256
620da112 conn=2871220 op=0 BIND dn="cn=admin,dc=ClinicalPortal" method=128
';
preg_match_all($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