How do I find out the process id of the backgrounded process?

I've got a command (program) that I'd like to run with nohup and background it. Like

nohup command > logfile.txt &

How do I find out the process ID? I would like to be able to write the process id in a file, read it later and kill the process programatically.

Solution

In your script:

nohup command > logfile.txt &
echo $! > /var/run/command.pid