title: How to set up continuous integration for Unity on Linux
body: <p>I would like to create a system for building a Unity project each time it is changed with git. I would like to use <a href="https://semaphoreci.com/lahsunity/multiplayer-fps-networking-ci-experiment/settings/scheduled_build_settings/new" rel="nofollow noreferrer">Semaphore</a> or <a href="https://www.shippable.com/" rel="nofollow noreferrer">Shippable</a> because of the free plan options. However, I don't know how to set up a system to automatically build a Unity project on Linux. Online, I can find documentation on how to do it for Mac with TravisCI, but this is not an option for me. How could I install Unity onto Ubuntu from the command line and then use the CLI build a project from a git repo? Thanks!</p>