'exec' command blocks the running of php script when execute SchTasks

Question

I use the following script php to schedule task of archive :

$archive_command = 'SchTasks /Create /SC monthly /MO lastday /TN archive'.date('Y_m').' /TR PHP_BINARY." ".$SCRIPT_DIR.archive.php /M * /ST 23:30';
exec("$archive_command 2>&1");

but when execute SchTasks to recreate the same task it blocks the execution of the php script. How to avoid this blocking ?

Answer 1

Try with this

pclose(popen("$archive_command 2>&1 &", "r"));

UPDATE: I have picked this function from another site :

function bgExec($cmd) {
    if(substr(php_uname(), 0, 7) == "Windows"){
        pclose(popen("start /B ". $cmd, "r")); 
    } else {
        exec($cmd . " > /dev/null &"); 
 }
}

Answer 2

There is a way to force shell to return immediately by appending ampersand to the command line with popen :

#                            ⇓
popen("$archive_command 2>&1 &", "r");

If this is OK with you, fine. If not, let me know. There is another more complicated way to resolve an issue with starting shell in another thread.