PHP exec，多个命令，不要等待

I'm trying to run multiple commands through exec without having my PHP script waiting. So far this is what I have but its not working correctly

unzip_file_command ; process_files_command ; delete_unneeded_files  > /dev/null 2>&1  &

Any thoughts as to why this isn't working correctly? I've tried adding nohup to the beginning of the whole command, to the beginning of each, and also adding > /dev/null before each ;. I've tried a bunch of combinations but no luck. Any thoughts? Thanks!

If you run multiple commands with exec, you need to specify the

 > /dev/null 2>&1 &

for each command separately not just once at the end of the exec. If only placed at the end, it is applied to the last command and you wait the others.

Then you need to place each command inside parenthesis because of the ampersand. So the end result would be:

(commandA > /dev/null 2>&1 &) ; (commandB > /dev/null 2>&1 &)

So I ended up creating a shell script and running that through exec with '> /dev/null 2>&1 &' at the end. It seems to have solved the problem.