Installing and starting jack

Before installing Jack, make sure that you actually want to install Jack. If you are on a fairly up-to-date Linux system you are likely better off with PipeWire. It may already be installed and running without you having realized it. Read the Linux Audio Primer first to make an informed choice.

Linux Audio Setup

sudo apt-get install jackd qjackctl openjdk-8-jdk

You'll need to get the jack audio daemon running, and we recommend qjackctl to figure out what command will be best to use. Then once you have it dialed in you can switch to using the terminal. For best performance you need to install a realtime enabled kernel, which allows the audio system to get high scheduled immediately when there is data to process. With purely generative music this isn't such a big deal, but if you want to jam with other instruments or process external sound in realtime then you'll want to invest the effort in setting up an rt-kernel. Ubuntu studio makes it pretty easy, especially if you aren't experienced in compiling the kernel. In the meantime, just turn-off the realtime support in the qjacktl options, and the audio server should boot.

You can create a .jackdrc file with this command to automatically start the jack server on boot, or you will need to run it manually to start the Jack audio server:

jackd -r -d alsa -r 44100

If you get errors from the above try:

jackd -r -d alsa -r 44100 -P

An alternative is to use the qjackctl gui. If you want to use jack through pulseaudio on dbus enabled distros like Arch or Ubuntu 15.04 of linux see here

We hope to support ALSA audio in future versions.

If pulseaudio is running while starting jackd, either jackd will not start properly or jackd will mute all other applications. What we might want to do is to connect pulseaudio and jackd in a sequence, demonstrated here (although, it's not completely without problems): http://www.youtube.com/watch?v=6J-RQudJx30

The safer way is to follow option #4 from http://jackaudio.org/faq/pulseaudio_and_jack.html

An alternative option, if you don't need pulseaudio running, is to kill pulseaudio and then run jackd. Here's more information: http://askubuntu.com/a/232163/22073

If you can't start jackd without root rights

jackd needs an appropriate privelege to run. This post details a solution: http://ubuntuforums.org/showthread.php?t=1637399&p=10199399#post10199399

Note for Fedora Users

It has been reported that the command jack_lsp is required and may be obtained by installing the fedora package jack-audio-connection-kit-example-clients