Ever been disconnected from your ssh session while in the middle of something? Ever wished there was a way to reconnect to that lost ssh session? Screen is for you..

Screen is a full-screen window manager that multiplexes a physical terminal between several processes. In fact, when you execute screen, you can imagine that you turned on another screen to the server that you're working on. You then execute your process on that virtual screen, detach your connection from it and return, whenever you please, to that screen in order to continue working.

Screen is a full-screen window manager that multiplexes a physical terminal between several processes, typically interactive shells. Each virtual terminal provides the functions of the DEC VT100 terminal and, in addition, several control functions from the ANSI X3.64 (ISO 6429) and ISO 2022 standards (e.g., insert/delete line and support for multiple character sets). There is a scrollback history buffer for each virtual terminal and a copy-and-paste mechanism that allows the user to move text regions between windows. When screen is called, it creates a single window with a shell in it (or the specified command) and then gets out of your way so that you can use the program as you normally would. Then, at any time, you can create new (full-screen) windows with other programs in them (including more shells), kill the current window, view a list of the active windows, turn output logging on and off, copy text between windows, view the scrollback history, switch between windows, etc. All windows run their programs completely independent of each other. Programs continue to run when their window is currently not visible and even when the whole screen session is detached from the users terminal.

I'm not sure it really fits as a separate 'tool' but since so many seem to not know about it, I thought it worthy of posting.

See also: https://savannah.gnu.org/projects/screen/