tmux: terminal multiplexing made simple

tmux lets you create multiple terminal sessions inside one window, split the screen into panes, and most importantly, keep sessions alive when you disconnect from SSH. If you’ve ever lost a long-running process because your SSH connection dropped, tmux is the answer.

Why tmux

Session persistence — disconnect from SSH, reconnect later, everything is still running
Multiple windows — like browser tabs for your terminal
Split panes — see multiple things at once in one terminal
Shared sessions — two people can attach to the same session (pair programming, debugging)

Starting tmux

tmux

That creates a session and attaches to it. You’re now inside tmux.

Detach (leave tmux running, return to normal terminal):

Ctrl+b d

Reattach:

tmux attach
# or
tmux a

List sessions:

tmux ls

Named sessions:

tmux new -s work
tmux attach -t work

Windows (tabs)

Create a new window: Ctrl+b c Switch to next window: Ctrl+b n Switch to previous window: Ctrl+b p Switch by number: Ctrl+b 0 (or 1, 2, etc.) List windows: Ctrl+b w Rename window: Ctrl+b , Close window: Ctrl+b &

Panes (splits)

Split horizontally: Ctrl+b % Split vertically: Ctrl+b " Switch to next pane: Ctrl+b o Switch by direction: Ctrl+b ←↑↓→ Close pane: Ctrl+b x Zoom pane (fullscreen toggle): Ctrl+b z Resize pane: Ctrl+b Ctrl+←↑↓→

Copy mode

Enter copy mode: Ctrl+b [ Navigate with arrow keys or vi keys (j/k) Start selection: Space (in vi mode) Copy selection: Enter Paste: Ctrl+b ] Exit copy mode: q

Configuration

tmux config goes in ~/.tmux.conf. Some useful settings:

# Enable mouse support
set -g mouse on

# Start window numbering from 1
set -g base-index 1
setw -g pane-base-index 1

# Increase history limit
set -g history-limit 50000

# Vi-style copy mode
setw -g mode-keys vi

# Reload config
bind r source-file ~/.tmux.conf \; display "Config reloaded"

Practical workflows

Long-running tasks:

tmux new -s deploy
# start your deployment script
# detach with Ctrl+b d
# reconnect later with tmux attach -t deploy

Multiple projects:

tmux new -s frontend
tmux new -s backend
tmux new -s ops

Switch between them with tmux switch -t name.

Side-by-side logs:

tmux
# split vertically: Ctrl+b %
# in left pane: tail -f /var/log/nginx/access.log
# click to right pane: Ctrl+b o
# in right pane: tail -f /var/log/nginx/error.log

tmux vs screen

GNU screen does similar things. tmux has:

Better split pane support
Scriptable (you can automate layouts)
Cleaner configuration
Active development

screen is older and simpler. If you’re choosing today, tmux is the better option.

Common tmux commands

tmux                    # new session
tmux new -s name        # named session
tmux ls                 # list sessions
tmux attach -t name     # attach to session
tmux kill-session -t name  # kill a session
tmux kill-server        # kill tmux entirely

Common mistakes

Not using tmux for remote work. Every SSH session that runs a long task should be inside tmux. Connection drops are inevitable.

Nested tmux. If you SSH from a tmux session into another server running tmux, the keybindings conflict. Use different prefix keys or use tmux only on the remote server.

Not knowing how to exit. exit or Ctrl+d closes the current pane/window. When the last pane closes, the session ends.

Remarks

tmux is one of those tools that, once you learn it, you wonder how you lived without it. The basics — new session, split pane, detach/attach — take 10 minutes to learn. The investment pays off every time your SSH connection drops and your work is still there.