<?php $a = exec("./a.sh"); var_dump($a);
#!/bin/bash echo "11" (sleep 10) &
#!/bin/bash echo "11" (sleep 10 > /dev/null) &
If a program is started with this function, in order for it to continue running in the background, the output of the program must be redirected to a file or another output stream. Failing to do so will cause PHP to hang until the execution of the program ends.