$re = '/(?m)^line\scon.*(?:\n .+)*/m';
$str = '!
line con 0
session-timeout 5
exec-timeout 5 0
password 7 1239211A43054F0202D1D
transport output none
line 2
no activation-character
no exec
transport preferred none
transport output pad telnet rlogin lapb-ta mop udptn v120 ssh
stopbits 1
line vty 0 4
session-timeout 5
access-class 125 in
exec-timeout 5 0
length 0
transport input ssh
transport output none';
preg_match_all($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