why php command `exec("service apache2 restart");` does't work on ubuntu?

Question

I need to execute some commands on my web server with php configured with apache.

exec("service apache2 restart", $output);
print_r($output);

output:

Array (
    [0] =>  * Restarting web server apache2
    [1] => Action 'start' failed.
    [2] => The Apache error log may have more information.
    [3] =>    ...fail! 
)

My guess is it's because of permissions of php on my ubuntu! What do you suggest?

If you run it via the web like http://localhost/restartserver.php, it's going to run as the www-data user. By default, the www-data user does not have permission to restart the web server. — joar
– joar, Commented Nov 20, 2011 at 16:27

Gilles Quénot · Accepted Answer · 2011-11-20 17:56:47Z

9

You need to run :

visudo

check that you have a line like

Host_Alias LOCAL=192.168.0.1

with your own local IP at the top of the file, then add a line

www-data       LOCAL=NOPASSWD:/usr/bin/service

And last in your PHP file :

exec("/usr/bin/sudo /usr/bin/service apache2 restart");

(You are trying to restart apache by web, maybe you don't know webmin interface ? I think there's betters solutions than this sudo way. It's not a good thing to authorize www-data to stop, start (...) all the services. Better explain why you'd like to restart apache ;) )

edited Nov 20, 2011 at 17:56

answered Nov 20, 2011 at 17:08

Gilles Quénot

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4 Comments

EBAG Over a year ago

Thanks for your working method! that's what i needed! I'm just doing this for test, not real project.

Jack Over a year ago

Will this work with other services like named? Can you explain what these lines do exactly?

Gilles Quénot Over a year ago

Sure it will works. RTFM, there's a lot of doc about this ;)

Jack Over a year ago

More for others who come here. All works for me. Cheers though!

joschi · Accepted Answer · 2011-11-20 16:29:33Z

2

Services (in the sense of system services, like Apache httpd) can only be manipulated (started, stoppped, restarted) by the root user (UID 0).

Either you run the PHP script in root's context (bad idea) or you use something like sudo to run the commands as super user. This said, there are very serious security implications when running programs with super user privileges, especially if you don't sanitize your inputs properly!

answered Nov 20, 2011 at 16:29

joschi

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Comments

John Zwinck · Accepted Answer · 2011-11-20 16:28:09Z

1

Did you look at the Apache error log like it says? What's in there?

Almost certainly your PHP script is running without sufficient permissions to restart Apache. Which is probably for the best. If you really really need this to work, consider making a setuid root script to invoke from PHP (note that this should not be used in production, and will probably create a security hole).

You could also write a little service which runs as root and accepts commands to restart Apache from your PHP script. That'd be a more "proper" way of doing this, though the task at hand seems itself improper, so I'm not sure you should continue down this path.

answered Nov 20, 2011 at 16:28

John Zwinck

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