If you’ve ever SSHed into a server, started a long-running process, and then lost your connection — you already know why tmux exists. It’s a terminal multiplexer: it lets you run multiple terminal sessions inside a single connection, detach from them, come back later, and pick up exactly where you left off. Once it’s in your workflow, working without it feels broken.

Installing tmux

On macOS:

$ brew install tmux

On Debian/Ubuntu:

$ sudo apt-get install tmux

Check the version — anything 3.x is solid:

$ tmux -V
tmux 3.4

Core Concepts

tmux has three layers of hierarchy:

  • Session — a collection of windows. You can detach from a session and it keeps running.
  • Window — like a tab. One session holds multiple windows.
  • Pane — a split inside a window. One window holds multiple panes.

The prefix key is the gateway to all tmux commands. The default is Ctrl-b. Every shortcut below assumes you press Ctrl-b first, then the listed key.

Starting and Managing Sessions

Start a new unnamed session:

$ tmux

Start a named session (recommended — easier to reattach later):

$ tmux new -s work

List running sessions:

$ tmux ls
work: 2 windows (created Sat May 23 10:00:00 2026) [220x50]

Detach from the current session (leaves it running in the background):

Ctrl-b d

Reattach to a named session:

$ tmux attach -t work

Kill a session:

$ tmux kill-session -t work

Windows (Tabs)

Shortcut Action
Ctrl-b c Create a new window
Ctrl-b , Rename the current window
Ctrl-b n Next window
Ctrl-b p Previous window
Ctrl-b 0–9 Switch to window by number
Ctrl-b w Interactive window list
Ctrl-b & Kill the current window (prompts for confirmation)

A good naming habit: rename windows to reflect what’s running in them (server, logs, db, etc.). The status bar at the bottom shows all windows at a glance.

Panes (Splits)

Shortcut Action
Ctrl-b % Split vertically (left/right)
Ctrl-b " Split horizontally (top/bottom)
Ctrl-b Arrow Move between panes
Ctrl-b z Zoom/unzoom the current pane (full-screen toggle)
Ctrl-b x Kill the current pane
Ctrl-b q Show pane numbers briefly
Ctrl-b { / } Swap pane position with the previous/next
Ctrl-b Ctrl-Arrow Resize pane by one cell

A typical layout for local development: one pane running your dev server, one for your editor, one for a shell. Zoom in on whichever you need at the moment.

Copy Mode

tmux has a built-in scroll buffer and copy mode. Enter it with:

Ctrl-b [

Once in copy mode:

  • Arrow keys (or vi keys if configured) move the cursor
  • / searches forward, ? searches backward
  • Space starts a selection, Enter copies it
  • q exits copy mode

Paste the copied text with Ctrl-b ].

Customizing with ~/.tmux.conf

The default keybindings aren’t ideal. A minimal ~/.tmux.conf that most people settle on:

# Remap prefix from Ctrl-b to Ctrl-a (screen-style)
unbind C-b
set-option -g prefix C-a
bind-key C-a send-prefix

# Split panes with | and -
bind | split-window -h
bind - split-window -v
unbind '"'
unbind %

# Vim-style pane navigation
bind h select-pane -L
bind j select-pane -D
bind k select-pane -U
bind l select-pane -R

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

# Enable mouse support
set -g mouse on

# Increase scrollback buffer
set -g history-limit 10000

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

# True color support
set-option -g default-terminal "screen-256color"
set-option -sa terminal-overrides ",xterm-256color:RGB"

After editing, reload without restarting:

Ctrl-b r    (or Ctrl-a r if you remapped the prefix)

Practical Workflows

Remote dev with persistent sessions

SSH to a server, create a named session, start your work:

$ ssh user@myserver.com
$ tmux new -s deploy
# run your build, migration, whatever
$ Ctrl-a d   # detach
$ exit       # close SSH

Later, SSH back and reattach:

$ ssh user@myserver.com
$ tmux attach -t deploy

The session survived your disconnection — everything is exactly as you left it.

Multiple services at a glance

$ tmux new -s dev
# in pane 1: run the API
$ npm run dev

# split and run the database
$ Ctrl-a |
$ docker compose up postgres

# split again for a shell
$ Ctrl-a -

Zoom into any pane with Ctrl-a z when you need to focus.

Scripting session layouts

For a reproducible dev environment, start tmux with a shell script:

#!/bin/bash
tmux new-session -d -s dev -n editor
tmux send-keys -t dev:editor 'nvim .' C-m

tmux new-window -t dev -n server
tmux send-keys -t dev:server 'npm run dev' C-m

tmux new-window -t dev -n logs
tmux send-keys -t dev:logs 'tail -f /var/log/app.log' C-m

tmux select-window -t dev:editor
tmux attach-session -t dev

Run this script instead of tmux and you get a fully configured session in one command.

tmux Cheat Sheet

Action Command
New session tmux new -s name
Attach session tmux attach -t name
List sessions tmux ls
Kill session tmux kill-session -t name
Detach Ctrl-b d
New window Ctrl-b c
Rename window Ctrl-b ,
Next/prev window Ctrl-b n / Ctrl-b p
Split vertical Ctrl-b %
Split horizontal Ctrl-b "
Navigate panes Ctrl-b Arrow
Zoom pane Ctrl-b z
Copy mode Ctrl-b [
Paste Ctrl-b ]
Reload config Ctrl-b r (if bound)

Conclusion

tmux is the difference between a fragile terminal workflow and a resilient one. The key insight is that sessions outlive your SSH connection or terminal window — your work keeps running whether you’re there or not. Start by learning sessions and detach/attach, then gradually adopt windows and panes as your workflow grows. The ~/.tmux.conf customization above covers 90% of what most developers need, and you can always extend it later.