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

Bill Purvis bill at billp.org
Mon Oct 9 20:09:33 UTC 2017

On 09/10/17 19:15, Athanasios Silis wrote:
> 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
> _______________________________________________
> Linux-audio-user mailing list
> Linux-audio-user at lists.linuxaudio.org
> https://lists.linuxaudio.org/listinfo/linux-audio-user
ulimit is built-in to the command shell program. I'd suggest you encase 
your commands in a shell script
with the ulimit at the start, and invoke that, via su, from rc.local.

However, I suspect that will still reject the request. I'd suggest you 
look at starting the programs,
then use the renice command (see man renice) to alter the priority once 
they are running.
You need to be root to raise the priority of a process above normal.


| Bill Purvis                            |
| email: bill at billp.org                  |

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