crontab issue when using exec php script?

Question

I am using elementaryOS (base on ubuntu)

When I run commaand line:

kn3l@kn3l:/var/www/cronjob$ 
25 15 * * * /var/www/cronjob/helloworld.php > /var/www/cronjob/cron.log

and it works for crontab with terminal command line.

BUT When I using PHP with my code like this (test.php):

-rwxrwxrwx  1 kn3l kn3l    47 Jun  6 14:59 test.php*

test.php

<?php
    $output = shell_exec('crontab -l');
    echo "<pre>$output</pre>";

I go tohttp://localhost/test.php

Why I did not see any return like the command line?

Anyone could help me?

What user is executing the script the php file? Must be some apache, not your user. So it is showing the crontab for apache user. — fedorqui
– fedorqui, Commented Jun 6, 2013 at 9:02

Community · Accepted Answer · 2017-05-23 12:30:55Z

You have in your user crontab the following line:

25 15 * * * /var/www/cronjob/helloworld.php > /var/www/cronjob/cron.log

in crontab it is necessary to indicate which binary is executing the script. So as hw indicates, you need to replace it to

25 15 * * * <path to php> /var/www/cronjob/helloworld.php > /var/www/cronjob/cron.log

get this <path to php> with which php.

Regarding your test.php file, take into account that the command crontab -l is being executed by the user running the php script. That is, the user running your local server.

I did a test:

$ ps -ef | grep apac
.../...
www-data  1348  1332  0 09:50 ?        00:00:00 /usr/sbin/apache2 -k start

so in my case it is www-data the user running apache.

I added your file in /var/www:

<?php
    $output = shell_exec('crontab -l');
    echo "<pre>$output</pre>";
?>

And nothing appeared while executing it. Why? Because www-data has no crontab:

$ sudo crontab -l -u www-data
no crontab for www-data

I added a line:

$ sudo crontab -l -u www-data
* * * * * touch /tmp/tt

and now the php page shows:

* * * * * touch /tmp/tt

To sum up

The thing is not that your script is not working properly, is just that is showing an empty content as the crontab for user www-data is empty.

Yogus · Accepted Answer · 2013-06-06 09:05:23Z

2

try this

<?
$output = shell_exec('crontab -l');
file_put_contents('/tmp/crontab.txt', $output.'* * * * * NEW_CRON'.PHP_EOL);
echo exec('crontab /tmp/crontab.txt');
?>

answered Jun 6, 2013 at 9:05

Yogus

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Comments

zool · Accepted Answer · 2013-06-06 09:14:58Z

2

Add to first string to test.php

#!/usr/bin/php

answered Jun 6, 2013 at 9:14

zool

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Comments

hw. · Accepted Answer · 2013-06-06 09:02:03Z

1

You would have to execute the script in this fashion:

25 15 * * * /usr/bin/php /var/www/cronjob/helloworld.php > /var/www/cronjob/cron.log

Make sure that /usr/bin/php is valid on your system.

answered Jun 6, 2013 at 9:02

hw.

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1 Comment

hw. Over a year ago

Great. Does this answer your question then? If so, you can accept this answer.

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