Magento: Setup cronjob every 2 hours

For some reason this code in module's config.xml:

<jobs>
    <stockupdate>
       <schedule><开发者_运维问答cron_expr>0 */2 * * *</cron_expr></schedule>
        <run><model>stockupdate/cron::start</model></run>
    </stockupdate>
</jobs>

doesn't work. Although after changing */2 to * all seems to be alright.

To test it I first do a TRUNCATE cron_schedule, then clean the cache rm -rf var/cache then run php cron.php and then SELECT * FROM cron_schedule to see if job was scheduled.

I know there is also the nasty way 0 0,2,4,6,8,10,12,14,16,18,20,22 0 0 0 but this is a very inelegant solution.

So how I can tell Magento to run this task every 2 hours?

---

You could use

<schedule><cron_expr>0 * * * *</cron_expr></schedule>

and have your code check for even hours. Not elegant, but it would work. If it needs to be configurable you could add a configuration option to control how often it runs in hours.

Update:

Look at Mage_Cron_Model_Schedule in the matchCronExpression method:

    // handle modulus
    if (strpos($expr,'/')!==false) {
        $e = explode('/', $expr);
        if (sizeof($e)!==2) {
            throw Mage::exception('Mage_Cron', "Invalid cron expression, expecting 'match/modulus': ".$expr);
        }
        if (!is_numeric($e[1])) {
            throw Mage::exception('Mage_Cron', "Invalid cron expression, expecting numeric modulus: ".$expr);
        }
        $expr = $e[0];
        $mod = $e[1];
    } else {
        $mod = 1;
    }

    // handle all match by modulus
    if ($expr==='*') {
        $from = 0;
        $to = 60;
    }
    // handle range
    elseif (strpos($expr,'-')!==false) {
        $e = explode('-', $expr);
        if (sizeof($e)!==2) {
            throw Mage::exception('Mage_Cron', "Invalid cron expression, expecting 'from-to' structure: ".$expr);
        }

        $from = $this->getNumeric($e[0]);
        $to = $this->getNumeric($e[1]);
    }
    // handle regular token
    else {
        $from = $this->getNumeric($expr);
        $to = $from;
    }

    if ($from===false || $to===false) {
        throw Mage::exception('Mage_Cron', "Invalid cron expression: ".$expr);
    }

    return ($num>=$from) && ($num<=$to) && ($num%$mod===0);

It is setup to handle */2 properly.

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for every 2 hour use expression

<schedule><cron_expr>0 */2 * * *</cron_expr></schedule>

if you set

<schedule><cron_expr>* */2 * * *</cron_expr></schedule>

you will get, that task will be sheduled every minute each second hour. 60 tasks for second hour, 0 tasks for 3d hour, 60 tasks for 4 hour etc.

---

Try setting the cron task to * */02

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If you want every 2 hours, the expression would be:

<schedule>00 */2 * * *</schedule>

This will execute at minute 0 past every 2nd hour.

Check for more expressions