How to kill a running bash file with php

Question

I have two buttons "Start Acquisition" and "Stop Acquisition",

The start button executes a bash file and it works fine:

<form action="Control.php" method="post">
<input value="Continous Acquisition " name="Continuous" type="submit">
</form>

<?php
if (isset($_POST['Continous'])) {
shell_exec('sh /Desktop/run_test.sh');
}
?>

I have no idea how to stop the execution when the Stop button is pressed

<form action="Control.php" method="post">

<input value="Stop Acquisition " name="Stop" type="submit">

 </form>

Any help would be appreciated. Thank you.

Answer 1

To run a program in the background, the command should take this form:

nohup sh /Desktop/run_test.sh &

To stop the program, first find the process id (PID), assuming here that there is only one instance, otherwise you'll need to differentiate the instances:

$exec_output = array();
$actual_pid = 0;
exec("pgrep -fl /Desktop/run_test.sh", $exec_output);
if ($exec_output and preg_match('/^(\d+) .*$/', $exec_output[0], $match)) {
    $actual_pid = $match[1];
}

Then issue a kill command

if ($actual_pid != 0) exec("kill -9 $actual_pid");

Answer 2

When you use shell_exec , it is being run synchronously and waits for the script to complete. Instead, you may want to do something like this instead using proc_open() and proc_close() :

$descriptorspec = array(
    0 => array("pipe", "r"),  // stdin is a pipe that the child will read from
    1 => array("pipe", "w"),  // stdout is a pipe that the child will write to
    2 => array("file", "/tmp/error-output.txt", "a") // stderr is a file to write to
);

$cwd = '/tmp';

$process = proc_open('sh /Desktop/run_test.sh', $descriptorspec, $pipes);
if (is_resource($process))
{
    // We have a running process. We can now get the PID
    $info = proc_get_status($process);

    // Store PID in session to later kill it
    $_SESSION['current_pid'] = $info['pid'];
} 

Once you have the PID stored in the session (or a file or wherever you want to persist it), you could use system or exec to run a kill -9 $pid command.

References:

http://php.net/manual/en/function.proc-open.php http://php.net/manual/en/function.proc-get-status.php