Since we are using DevStack in this book, screen becomes a core concept of running DevStack. In this section, we will take a look at some screen commands and how we will be using them in order to interact with DevStack.
Screen is software that essentially is a window manager in Linux. It helps the user to use multiple shell windows from a single SSH session. This is recommended to be used when we have a long running command that needs to survive network disruptions.
Screen is normally used to run long running processes. DevStack creates and runs its entire services in its own screen and if you were to use the ~/devstack/restack.sh script, it would connect you to the already running screen session.
We installed screen as a prerequisite earlier in the chapter; let us now look at some of the commands that will help us.