Just a note regarding what rbemrose at vgmusic dot com said:
Once the executed process ends, control returns to the webserver process.
pcntl_exec
(PHP 4 >= 4.2.0, PHP 5)
pcntl_exec — Executes specified program in current process space
Description
$path
[, array $args
[, array $envs
]] )Executes the program with the given arguments.
Parameters
-
path -
pathmust be the path to a binary executable or a script with a valid path pointing to an executable in the shebang ( #!/usr/local/bin/perl for example) as the first line. See your system's man execve(2) page for additional information. -
args -
argsis an array of argument strings passed to the program. -
envs -
envsis an array of strings which are passed as environment to the program. The array is in the format of name => value, the key being the name of the environmental variable and the value being the value of that variable.
Return Values
Returns FALSE on error and does not return on success.
As a side note, if I'm reading the comments below correctly, you should not run this if you're using a PHP webserver module, as it will replace the webserver's process with whatever process you're telling it to run.
Some people might find it useful to run other program using the same process as a different user. This is very usefull if the script is running under root. Here is a simple code to achieve that under *nix PHP CLI:
#!/usr/bin/php -q
<?php
//Enter run-as user below (argument needed to be passed when the script is called), otherwise it will run as the caller user process.
$username = $_SERVER['argv'][1];
$user = posix_getpwnam($username);
posix_setuid($user['uid']);
posix_setgid($user['gid']);
pcntl_exec('/path/to/cmd');
?>
I use this as a part of socket program so that a program can be run under different user from remote location.
//To complete my last note
//If you use some object in your php code
//You will have some problem if you do a exit after include the
//child scripts
//You must use posix_kill() like that :
$CHILD_PID = pcntl_fork();
if($CHILD_PID == 0)
{
include ($script_path);
posix_kill(getmypid(),9);
}
//This code is very simple it can be ameliorate ;)
An alternative for Windows environment is to use the COM object. With this, you can start child process with Apache, or php.exe as parent process. Very useful for CLI or console PHC-Win applications.
if(!function_exists('pcntl_exec')){
function pcntl_exec($path,$args=array()){
if(is_string($args)) $args = array($args);
if(count($args)) $path = '"'.$path.'"';
$shell = new COM('WScript.Shell');
$shell->run($path.(count($args) ? ' '.implode(' ',$args) : ''),0,true);
}
}
Very useful too when you want to use ansicon. Instead of make a .bat file with ansicon -p and php .... (somefile).php, in your .php file you can put this on top of your code:
pcntl_exec('ansicon -p');
BINGO!
The pcntl_exec() function works exactly like the standard (unix-style) exec() function. It differs from the regular PHP exec() function in that the process calling the pcntl_exec() is replaced with the process that gets called. This is the ideal method for creating children. In a simple example (that does no error checking):
switch (pcntl_fork()) {
case 0:
$cmd = "/path/to/command";
$args = array("arg1", "arg2");
pcntl_exec($cmd, $args);
// the child will only reach this point on exec failure,
// because execution shifts to the pcntl_exec()ed command
exit(0);
default:
break;
}
// parent continues
echo "I am the parent";
--
since this is not being executed through a shell, you must provide the exact path from the filesystem root. Look at the execve() man page for more information.
I spent a lot of time trying to figure this powerful option out so I didn't get error 2 or error 8. The documentation says it can execute a binary file and here is a good example that works that I found;
<?php
print "Before\\n";
pcntl_exec("/usr/bin/uptime");
print "After\\n";
?>
However I wanted it to run another php program and after wasting a lot of time I finally got it.
<?php
$tasks2=array('/var/www/example.php');
pcntl_exec("/usr/bin/php",$tasks2);
?>
The php script has to be in an array and you execute the binary php file
I'll be adding this to launching a child and run it seperately using this function
<?php
function launchchild($programexe,$programvars)
{
//foreach ($tasks as $key => $v){
switch ($pid = pcntl_fork()) {
case -1:
// @fail
die('Fork failed');
break;
case 0:
// @child: Include() misbehaving code here
print "FORK: Child #{$x} \\n";
echo "child after fork:", getmypid(), PHP_EOL;
pcntl_exec($programexe,$programvars);
// generate_fatal_error(); // Undefined function
break;
default:
// @parent
print "FORK: $x Parent\\n";
echo "parent after fork:", getmypid(), PHP_EOL;
// pcntl_waitpid($pid, $status);
break;
}
print "Done! :^)\\n\\n";
}
?>
//If you are in php version between 4.1 and 4.2
//When you use pcntl_fork and after you want use
//pcntl_exec, you can because pcntl_exec isn't used before
//php 4.2 so let me show a solution :
$CHILD_PID = pcntl_fork();
if($CHILD_PID == 0)
{
include ($script_path);
exit;
}
//$script_path is the *.php page which you want lauch like
// a child .
//I don't know why php coder hadn't add pcntl_exec in the
//same time that other function
//Michaël F. php developer .
