tmux

tmux ("terminal multiplexer") lets a single terminal host multiple independent shell sessions, split into panes and organised into windows, and, critically, keeps them alive when you disconnect. Over SSH this means a long-running job survives a dropped connection, and you can re-attach exactly where you left off.

tmux                     # start a new session
tmux new -s work         # named session
tmux ls                  # list sessions
tmux attach -t work      # re-attach
tmux kill-session -t work

Inside tmux, the prefix key (Ctrl-b by default) starts every command: Ctrl-b c creates a window, Ctrl-b " splits the current pane horizontally, Ctrl-b % vertically, Ctrl-b d detaches. Configuration lives in ~/.tmux.conf. Many users rebind the prefix to Ctrl-a (matching screen) and enable mouse support and vi-style keys.