[LAU] changing ulimit from rc.local in order to start audio scripts from there

Hi there, I have setup an audio system around jackd based on ubuntu studio (14.04 LTS). I have written various scripts to setup jackd and clients. It is tested and up running. Now I would like to add a cmd in rc.local in order for the whole system to be brought up at boot. I tried #set limits su - nass -c "ulimit -r 95 -l unlimited" 2>&1 | tee -a /tmp/audio.log #verify limits su - nass -c "ulimit -r -l" 2>&1 | tee -a /tmp/audio.log #boot audio stuff su - nass -c "cd /home/nass/audio_setup/scripts ; bash ./cmdaudio start" 2>&1 | tee -a /tmp/audio.log However the ulimit "set" command fails with message ulimit: real-time priority: cannot modify limit: Operation not permitted I read that ulimits are not ready yet at this time. Is there a way to forcefully "bring them up" in order to have them set for the user "nass" before starting the audio scripts ?? Thank you