CODE EXAMPLE FOR PHP

preg match apache log file

$regex = '/^[([^]]+)] [([^]]+)] (?:[client ([^]]+)])?s*(.*)$/i';
preg_match($regex, $log, $matches);
$matches[1] = Date and time,           $matches[2] = severity,
$matches[3] = client addr (if present) $matches[4] = log message