Screen is useful tool but it does have some slight bugs such as when you use the SU command to switch to another user and attempt to use screen you will most probably receive a error message similar to the following.

This issue only occurs when you switch to another user account using SU (switch user) then try to perform a screen action.

Running this command after switching to you desired user will stop this error message appearing and normal usage of screen can continue.

Screen is a powerful shell tool allowing a user to spawn multiple shells called “screens” each screen will continue to run in the background even after the SSH connection has ended. This allows a server owner to run programs, services and servers without having to keep a SSH connection active.