# m h dom mon dow command
* * * * * date > /tmp/cron.date.run

* * * * * /usr/bin/php cron.php

// 從./crontab讀取cron項,也可以從其他持久存儲(mysql、redis)讀取
$crontab = file('./crontab');
$now = $_SERVER['REQUEST_TIME'];

PHP實戰foreach ( $crontab as $cron ) {
?$slices = preg_split("/[\s]+/", $cron, 6);
?if( count($slices) !== 6 ) continue;

PHP實戰?$cmd?????? = array_pop($slices);
?$cron_time = implode(' ', $slices);
?$next_time = Crontab::parse($cron_time, $now);
?if ( $next_time !== $now ) continue;?

PHP實戰?$pid = pcntl_fork();
?if ($pid == -1) {
??die('could not fork');
?} else if ($pid) {
??// we are the parent
??pcntl_wait($status, WNOHANG); //Protect against Zombie children
?} else {
????? // we are the child
??`$cmd`;
??exit;
?}
}

PHP實戰/* https://github.com/jkonieczny/PHP-Crontab */
class Crontab {
?? /**
?* Finds next execution time(stamp) parsin crontab syntax,
?* after given starting timestamp (or current time if ommited)
?*
?* @param string $_cron_string:
?*
?* 0 1 2 3 4
?* * * * * *
?* - - - - -
?* | | | | |
?* | | | | +----- day of week (0 - 6) (Sunday=0)
?* | | | +------- month (1 - 12)
?* | | +--------- day of month (1 - 31)
?* | +----------- hour (0 - 23)
?* +------------- min (0 - 59)
?* @param int $_after_timestamp timestamp [default=current timestamp]
?* @return int unix timestamp - next execution time will be greater
?* than given timestamp (defaults to the current timestamp)
?* @throws InvalidArgumentException
?*/
??? public static function parse($_cron_string,$_after_timestamp=null)
??? {
??????? if(!preg_match('/^((\*(\/[0-9]+)?)|[0-9\-\,\/]+)\s+((\*(\/[0-9]+)?)|[0-9\-\,\/]+)\s+((\*(\/[0-9]+)?)|[0-9\-\,\/]+)\s+((\*(\/[0-9]+)?)|[0-9\-\,\/]+)\s+((\*(\/[0-9]+)?)|[0-9\-\,\/]+)$/i',trim($_cron_string))){
??????????? throw new InvalidArgumentException("Invalid cron string: ".$_cron_string);
??????? }
??????? if($_after_timestamp && !is_numeric($_after_timestamp)){
??????????? throw new InvalidArgumentException("\$_after_timestamp must be a valid unix timestamp ($_after_timestamp given)");
??????? }
??????? $cron = preg_split("/[\s]+/i",trim($_cron_string));
??????? $start = empty($_after_timestamp)?time():$_after_timestamp;

PHP實戰??????? $date = array( 'minutes' =>self::_parseCronNumbers($cron[0],0,59),
??????????????????????????? 'hours' =>self::_parseCronNumbers($cron[1],0,23),
??????????????????????????? 'dom' =>self::_parseCronNumbers($cron[2],1,31),
??????????????????????????? 'month' =>self::_parseCronNumbers($cron[3],1,12),
??????????????????????????? 'dow' =>self::_parseCronNumbers($cron[4],0,6),
??????????????????????? );
??????? // limited to time()+366 - no need to check more than 1year ahead
??????? for($i=0;$i<=60*60*24*366;$i+=60){
??????????? if( in_array(intval(date('j',$start+$i)),$date['dom']) &&
??????????????? in_array(intval(date('n',$start+$i)),$date['month']) &&
??????????????? in_array(intval(date('w',$start+$i)),$date['dow']) &&
??????????????? in_array(intval(date('G',$start+$i)),$date['hours']) &&
??????????????? in_array(intval(date('i',$start+$i)),$date['minutes'])

PHP實戰??????????????? ){
??????????????????? return $start+$i;
??????????? }
??????? }
??????? return null;
??? }

PHP實戰??? /**
?* get a single cron style notation and parse it into numeric value
?*
?* @param string $s cron string element
?* @param int $min minimum possible value
?* @param int $max maximum possible value
?* @return int parsed number
?*/
??? protected static function _parseCronNumbers($s,$min,$max)
??? {
??????? $result = array();

PHP實戰??????? $v = explode(',',$s);
??????? foreach($v as $vv){
??????????? $vvv = explode('/',$vv);
??????????? $step = empty($vvv[1])?1:$vvv[1];
??????????? $vvvv = explode('-',$vvv[0]);
??????????? $_min = count($vvvv)==2?$vvvv[0]:($vvv[0]=='*'?$min:$vvv[0]);
??????????? $_max = count($vvvv)==2?$vvvv[1]:($vvv[0]=='*'?$max:$vvv[0]);

PHP實戰??????????? for($i=$_min;$i<=$_max;$i+=$step){
??????????????? $result[$i]=intval($i);
??????????? }
??????? }
??????? ksort($result);
??????? return $result;
??? }
}