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Screen is a full-screen window manager that acts as a terminal multiplexer. With it, any number of console-based applications can be run within a single terminal. Screen also has the ability to decouple the terminal emulator from the running programs. This allows programs started from screen to continue running after the connection to the terminal is lost, whether accidently, or with a logout. These programs can later be connected to again using screen.

How to use

Starting Screen

Screen is installed on all the UNIX workstations. To use screen to run a remote process, first you must connect to a remote machine. We have Putty installed on the Windows systems and OpenSSH installed on the UNIX machines. For more information on using ssh, please read this guide.

Once connected to a remote server, start a new screen session. This is accomplished by typing in "screen" (no quotes) at the terminal. The screen should blank for a second and then give you a prompt.

Detaching Screen

Once screen is running, processes that are started through screen will allow you to disconnect from the server without halting the process. Once it has started you need to disconnect your screen session. To do this you must type Ctrl-a d (hold "Ctrl" and "a" at the same time, release them and hit "d"). You should get a message stating that the session was "[detached]". Feel free to log out of the terminal.

Reattaching Screen

To check the results or status of the programs, log back in to the same server. Instead of typing "screen" as when starting, type "screen -r". The -r is for reconnect. This should reconnect the earlier screen session.

Note: If more than one screen session is running per user on a server, reconnecting screens requires an additional step. After running "screen -r", the user will receive a response of "There are several suitable screens on:" followed by a list of screen sessions available. Select the desired screen session, and run "screen -r [jobid]", replacing [jobid] with the desired session's id number.

Getting Help in Screen

Screen does much, much more than described above. You can type Ctrl-a? for a list of commands available while in screen.