execute linux command background in php

Question

I need to execute a command in linux by using php and it should meet following requirement.

• should create log file
• should run as background

I know how to do it separately,

with log file :

shell_exec("command 1>log 2>&1");

as background:

shell_exec("command /dev/null 2>&1 &");

My question is how to do it together ?

Answer 1

shell_exec("command 1>log 2>&1 &");