tmux basics

tmux survives SSH disconnects because its server process is independent of your SSH session. When you SSH without tmux:

SSH client → SSH connection → bash (your shell)
                                └─ your processes (children of bash)

When the SSH connection drops, the kernel sends SIGHUP to bash. Bash sends SIGHUP to all its children, then exits. Your processes die.

With tmux:

SSH client → SSH connection → tmux client → tmux server (independent process)
                                                └─ your sessions / windows / panes

The tmux server is started the first time you run tmux. It continues running as a daemon on the remote machine regardless of SSH connections. When your SSH drops, only the tmux client dies — the server and everything inside it keep running. Reconnect via SSH, reattach the client, and you are back.

Start and name sessions; understand the three-tier hierarchy. The basic hierarchy:

• Session — a collection of windows; has a name; survives disconnects.
• Window — one full-screen terminal inside a session; like a browser tab.
• Pane — a rectangular split of a window; each pane has its own shell.

tmux new-session -s deploy    # create a new session named "deploy"
# or shorter:
tmux new -s deploy

Inside a session, the green status bar at the bottom shows the session name, window list, and hostname. Everything you do inside this session is owned by the tmux server and survives your SSH dropping.

List running sessions from outside tmux:

tmux list-sessions   # or: tmux ls

The prefix key C-b precedes every tmux command. All tmux key bindings start with pressing Ctrl+b (the prefix), releasing it, then pressing the command key. You do not hold Ctrl while pressing the second key.

Essential bindings:

The most important: C-b d detaches you from the session without stopping it. Everything inside keeps running. This is the operation that makes tmux valuable for long-running remote work.

Reattach to a session with tmux attach. After detaching or after your SSH reconnects:

tmux attach            # attach to the most recent session
tmux attach -t deploy  # attach to the session named "deploy"
tmux a -t deploy       # shorthand

If you have multiple sessions and forget their names:

tmux ls
# deploy: 2 windows (created Mon Jun 21 10:30:00 2026)
# monitor: 1 windows (created Mon Jun 21 09:15:00 2026)

Then attach by name. When you attach, the terminal renders the session exactly as it was: scrollback preserved, processes mid-execution, cursor position where you left it.

To kill a session (stop everything in it):

tmux kill-session -t deploy

Windows and panes let you multiplex one SSH connection. Practical workflow on a remote server: one window for your editor, one for the build, one for log tailing, all in a single SSH connection with a single tmux session.

# Window 0: running a build
make build

# C-b c → new window
# Window 1: tail application logs
tail -f /var/log/app/production.log

# C-b c → new window
# Window 2: monitor resources
htop

# C-b n / C-b p → switch between windows
# C-b 0 / C-b 1 / C-b 2 → jump directly to window by index

Panes split a window into regions:

C-b %     # split current pane left/right
C-b "     # split current pane top/bottom
C-b →     # move focus to right pane

Each pane is a full independent shell. You can watch logs in one pane while editing a config in another — all in the same SSH connection.