Question

in a simple startup script I wrote I have:

PID=`su user_name -c "daemon_name > /dev/null 2>&1 & echo \$!"`  
echo $PID  

The script is run as root. And the echo doesn’t really echo anything 🙂

If I input the exact same command in the shell, it works:

# su user_name -c "daemon_name > /dev/null 2>&1 & echo \$!"  
11831  
#  

Any ideas? Thanks.

EDIT: It was working fine before I tried to run the application as another user.
I was previously using this code:

PID=`daemon_name > /dev/null 2>&1 & echo $!`  
echo $PID  

and it worked fine as root

Answer 1

daemons are designed to fork multiple times so likely the PID returned from $! will not be the pid you want to work with later. You will probably have to do something like this:

ps -eo pid,command,lstart --sort lstart | grep 'daemon_name' | tail -1