tmux is a terminal multiplexer: it enables a number of terminals to be created, accessed, and controlled from a single screen.

tmux (terminal multiplexer) allows you to create a session that contains multiple windows and panes. You can split your terminal into side-by-side panes, keep long-running commands alive, and even disconnect (detach) and reconnect (attach) later — especially useful when working on remote servers over SSH.
$ sudo apt install tmux$ sudo dnf install tmux$ sudo pacman -S tmux$ apk add tmux$ brew install tmuxto comment.