Terminal multiplexer

A terminal multiplexer is a software application that can be used to multiplex several virtual consoles, allowing a user to access multiple separate terminal sessions inside a single terminal window or remote terminal session. It is useful for dealing with multiple programs from a command line interface, and for separating programs from the Unix shell that started the program.

Features

A terminal multiplexer can be thought of as a text version of graphical window managers, or as a way of putting virtual terminals into any login session. It is a wrapper that allows multiple text programs to run at the same time, and provides features that allow the user to use the programs within a single interface productively.

Persistence

Similar to VNC, a terminal multiplexer allows the user to start applications from one computer, and then reconnect from a different computer and continue using the same application without having to restart it. This makes migration between locations like work and home simple. Terminal multiplexers provide terminal-agnostic functionality so that users can disconnect and reconnect using different terminal types, allowing applications to continue running without being aware of the change in terminals.

Multiple windows

Multiple terminal sessions can be created, each of which usually runs a single application. The windows are numbered, and the user can use the keyboard to switch between them. Some GUI terminal emulators provide tabs or otherwise similar functionality to this. Each window has its own scroll-back buffer, so that output is captured even when the window isn't actively displayed, and that history can be saved even when migrating to another computer. Windows can be split-screened. While some text applications have this functionality built in, a terminal multiplexer allows any application to be split-screened alongside any number of other applications.

Session Sharing

Terminal multiplexers allow multiple computers to connect to the same session at once, enabling collaboration between multiple users. The same computer can also be used to make multiple simultaneous connections, providing alternative functionality to screen-splitting, particularly for computers with multiple monitors.

Implementations

• GNU Screen: the prototypical terminal multiplexer, first released in 1987

• splitvt: split terminal utility.^[1]
• Twin ("Text mode WINdow environment"): a full-fledged window manager for text windows. Initially started as an MS-DOS project, it was later ported to Linux.^[2][3][4]
• dvtm: Tiling window management for the console.^[5]
• tmux: A modern GNU Screen workalike; it is BSD-licensed, allows multiple panes (with optional Xterm mouse support), and has a scriptable command interface.^[6][7][8] tmux aimed to allow the sharing of a single window between multiple terminals, while keeping the other windows in the same session entirely separate.^[9] tmux has been part of the OpenBSD base system since 2009's version 4.6.^[10]
• Byobu: A profile and configuration utility for GNU Screen and tmux.
• neercs: neercs ("screen" spelled backwards) is a GNU screen workalike. It supports window thumbnailing and graphical animated screensavers. It also supports 3D console switching (switching between consoles mapped to the faces of a cube) via the libcaca ASCII art library.

References