Terminal Multiplexers

tmux (and the older screen) run a persistent terminal session on the server itself, independent of any one SSH connection - detach from work in progress, log out, and reattach later to find everything exactly as you left it.

Shell Updated August 29, 2026

  • shell
  • tmux
  • screen

An SSH connection dying mid-task - a dropped Wi-Fi connection, a closed laptop lid - normally takes everything running in that shell down with it (see Job Control for why: it's SIGHUP). A terminal multiplexer runs the actual session on the remote machine, so the SSH connection becomes just a window onto it rather than the thing keeping it alive.

The core idea: sessions survive disconnection

tmux new -s deploy      # start a new named session
# ...work happens here...
# Ctrl+B, D             # detach - session keeps running in the background

tmux attach -t deploy   # reattach later, from any SSH connection, even a different one
tmux ls                 # list all running sessions

Detaching isn't the same as closing the terminal - the session and everything running inside it (a build, a long-running script, an interactive top) keeps going on the server whether or not anything is attached to watch it.

tmux: sessions, windows, and panes

tmux nests three levels: a session (the persistent container) holds one or more windows (like browser tabs), each of which can be split into multiple panes (side-by-side or stacked terminals).

All tmux keybindings start with a prefix - Ctrl+B by default, held and released before the next key:

Keys (after Ctrl+B) Action
D Detach from the session
C Create a new window
N / P Next / previous window
0-9 Jump to window number
% Split pane vertically
" Split pane horizontally
Arrow keys Move between panes
[ Enter copy mode (scroll back, select text with keyboard) 
tmux new -s work -n editor    # new session, first window named "editor"
tmux new-window -n logs       # add another window, from inside tmux
tmux rename-session -t work deploy   # rename a session
tmux kill-session -t deploy   # end a session and everything running in it

Configuration

~/.tmux.conf

Common tweaks: remapping the prefix key (Ctrl+A is a popular alternative, matching screen's default), enabling mouse support (set -g mouse on), and increasing scrollback history. Reload an edited config without restarting tmux with Ctrl+B then :source-file ~/.tmux.conf.

screen: the older alternative

screen predates tmux and is still preinstalled on some systems where tmux isn't. The core workflow is the same shape, different keys:

screen -S deploy         # start a named session
# Ctrl+A, D              # detach
screen -r deploy         # reattach
screen -ls               # list sessions

Functionally, tmux has mostly superseded screen - better pane splitting, scripting support, and active development - but screen's one advantage is being present by default on more minimal systems, so it's worth knowing the basics even if tmux is the daily driver.

Not a replacement for nohup/disown

A multiplexer and nohup/disown (see Job Control) solve overlapping but distinct problems: nohup keeps a single command running after disconnect, but gives no way back into its output. A multiplexer keeps an entire interactive session - including the ability to look at it again later - which is why it's the standard choice for anything you'll want to check back in on, rather than fire-and-forget.