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About php : sudo-in-php-exec

Question Detail

I don’t know what the deal is here…

So I want to run an applescript: sudo osascript myscript.scpt

This works fine in the terminal, but not when I execute it via PHP’s exec(); nothing happens. The console says

no tty present and no askpass program specified ; TTY=unknown ; …

I did my research, and it seems I’m missing the password for the sudo command. I tried a couple different ways to get around this, including:

  • writing %admin ALL=(ALL) ALL in /etc/sudoers
  • and proc_open() instead of exec()

none of which seem to be working, consequently driving me CrAzY!

So basically, is there a clear-cut way to get PHP to execute a simple terminal command?

EDIT: to clarify, myscript.scpt is a simple appleScript that changes the onscreen UI (for a larger project). In theory, simply osascript myscript.scpt should be enough, however the sudo is for some reason necessary to invoke some response from the system. If the sudo could be somehow eliminated, I don’t think I would be having this permissions problem.

Question Answer

It sounds like you need to set up passwordless sudo. Try:

%admin ALL=(ALL) NOPASSWD: osascript myscript.scpt

Also comment out the following line (in /etc/sudoers via visudo), if it is there:

Defaults    requiretty

I think you can bring specific access to user and command with visudo something like this:

nobody ALL = NOPASSWD: /path/to/osascript myscript.scpt

and with php:

@exec("sudo /path/to/osascript myscript.scpt ");

supposing nobody user is running apache.

php: the bash console is created, and it executes 1st script, which call sudo to the second one, see below:

$dev = $_GET['device'];
$cmd = '/bin/bash /home/www/start.bash '.$dev;
echo $cmd;
  1. /home/www/start.bash

    /usr/bin/sudo /home/www/myMount.bash $1
  2. myMount.bash:

    function error_exit
      echo "Wrong parameter" 1>&2
      exit 1

oc, you want to run script from root level without root privileges, to do that create and modify the /etc/sudoers.d/mount file:

www-data ALL=(ALL:ALL) NOPASSWD:/home/www/myMount.bash

dont forget to chmod:

sudo chmod 0440 /etc/sudoers.d/mount

I recently published a project that allows PHP to obtain and interact with a real Bash shell. Get it here: https://github.com/merlinthemagic/MTS
The shell has a pty (pseudo terminal device, same as you would have in i.e. a ssh session), and you can get the shell as root if desired. Not sure you need root to execute your script, but given you mention sudo it is likely.

After downloading you would simply use the following code:

$shell    = \MTS\Factories::getDevices()->getLocalHost()->getShell('bash', true);
$return1  = $shell->exeCmd('/path/to/osascript myscript.scpt');

Run sudo visudo command then set -%sudo ALL=(ALL:ALL) to %sudo ALL=(ALL:ALL) NOPASSWD: ALL it will work.

I had a similar situation trying to exec() a backend command and also getting no tty present and no askpass program specified in the web server error log. Original (bad) code:

$output = array();
$return_var = 0;
exec('sudo my_command', $output, $return_var);

A bash wrapper solved this issue, such as:

$output = array();
$return_var = 0;
exec('sudo bash -c "my_command"', $output, $return_var);

Not sure if this will work in every case. Also, be sure to apply the appropriate quoting/escaping rules on my_command portion.

The best secure method is to use the crontab. ie Save all your commands in a database say, mysql table and create a cronjob to read these mysql entreis and execute via exec() or shell_exec(). Please read this link for more detailed information.

          • killProcess.php

I think directly calling a sudo command might be difficult because you are setting up the whole server to work without a password.
Perhaps as an alternative you could setup a CRONjob as root and monitor a flag file. Once the flag file exists it will run the osascript myscript.scpt and then delete the flag file.
This way you will keep SUDO secure from a config point of view and the server safer. To run the script you just need to touch the flag file from PHP.
It would of course introduce a delay of however many minutes you running the CRON job. It would also mean that you would have to redirect the output to a file and have a async monitor of the output, but it will depend on your application if this is a problem or not.

But it is an alternative that might protect the server.

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