Solutions to php background task execution

About php background task execution. php calls B. php, B. in the php method, use php-cli to start a process. The question is, how to make. php does not wait B. php execution results I tried in B. add & amp; (php-fc.php & amp;) in php commands but not about php to execute background tasks
A. php calls B. php and B. php through http to start a process using php-cli,
The question is how to make a. php not wait for the execution result of B. php
I tried to add & (php-f c. php &) to the B. php command but it does not work. What else can I do?

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Someone has discussed this page.
Http://www.php.net/manual/en/function.exec.php