PHP中实现crontab代码分享

1. 准备一个标准crontab文件 ./crontab复制代码 代码如下:# m h dom mon dow command* * * * * date > /tmp/cron.date.run

2. crontab -e 将此cron.php脚本加入系统cron

复制代码 代码如下:* * * * * /usr/bin/php cron.php

3. cron.php 源码

复制代码 代码如下:// 从./crontab读取cron项，也可以从其他持久存储（mysql、redis）读取$crontab = file("./crontab");$now = $_SERVER["REQUEST_TIME"];

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

 $cmd       = array_pop($slices); $cron_time = implode(" ", $slices); $next_time = Crontab::parse($cron_time, $now); if ( $next_time !== $now ) continue; 

 $pid = pcntl_fork(); if ($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; }}

/* 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;

        $date = array( "minutes" =>self::_parseCronNumbers($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"])

                ){                    return $start+$i;            }        }        return null;    }

    /** * 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();

        $v = explode(",",$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]);

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