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.
pcntl_exec
(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
pcntl_exec — Executes specified program in current process space
Description
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. -
env_vars -
env_varsis 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.
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User Contributed Notes 6 notes
eric kilfoil ¶
18 years ago
agodong at verizon dot net ¶
18 years ago
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.
rbemrose at vgmusic dot com ¶
16 years ago
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.
fahadsadah at gmail dot com dot please dot remove dot this ¶
16 years ago
Just a note regarding what rbemrose at vgmusic dot com said:
Once the executed process ends, control returns to the webserver process.
michael dot ferre at mobileway dot com ¶
22 years ago
//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 ($script_path);
posix_kill(getmypid(),9);
}
//This code is very simple it can be ameliorate ;)
maxime at diametrick dot com ¶
11 years ago
An alternative for Windows environment is to use the COM object. With this, you can start child process with Apache, or php.exe as parent process. Very useful for CLI or console PHC-Win applications.
if(!function_exists('pcntl_exec')){
function pcntl_exec($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!
