Question

Ealier I used function in a seperate file that could be call by script for cron.

function processExists($file = false) {

   $exists     = false;
   $file       = $file ? $file : basename(__FILE__);

   $command = "ps -ef | grep -v grep | grep $file";
   exec($command, $pids);
   if (count($pids) > 1) {
      $exists = true;
   }
   return $exists;
}

It could be executed from any php script as:

if (processExists(basename(__FILE__))) {
   echo 'Process in already running ';
   exit(0);
}

For some reason it doesn’t work in Debian6.
Now I add in the beginning of every script:

$fh = fopen(__FILE__, 'r');
if (!flock($fh, LOCK_EX | LOCK_NB)) {
   echo 'Script is already running!!!' . "\n";
   exit(0);
}

It causes duplication of code in every script I tried to create function in a seperate file to call from any php script when neccessary, for example something like this:

function stopIfRunning($file)
{
    $fh = fopen($file, 'r');
    if(!flock($fh, LOCK_EX | LOCK_NB)) {
        echo 'Script is already running!!!' . "\n";
        exit(0);
    }
}

And calling from php script:

stopIfRunning(__FILE__);

But it doesn’t work in this case. Could you please explain why it doesn’t work in this case?

Answer 1

It seems the problem is with $fh on stopIfRunning function. If the file with with functiona changed it with:

$fh = null;
function stopIfRunning($file)
{
    global $fh;
    echo $file, "\n";
    $fh = fopen($file, 'r');
    if (!$fh) {
        echo 'Failed to open file', "\n";
    }
    if(!flock($fh, LOCK_EX | LOCK_NB)) {
        echo 'Script is already running!!!' . "\n";
        exit(0);
    }
}   

And call it in the file that should be launched using cron:

stopIfRunning(__FILE__);

Here global variable is used, which is not good. It would be great if somebody suggest a solution without global variable.