Use tmux for persistent sessions

When you close your SSH window, the shell goes with it, and any command still running is stopped. tmux is a terminal multiplexer that keeps your sessions alive on the server, so you can start a long job, disconnect, come back tomorrow, and pick up exactly where you left off.

Before you begin

A VPS running Ubuntu 24.04 LTS and SSH access as a user with sudo rights, such as alex.
A basic idea of the command line: running commands, and typing into a prompt.

Step 1: Install tmux

Update the package list so apt knows the latest versions, then install tmux. The -y flag answers "yes" to the install prompt.

sudo apt update
sudo apt install -y tmux

Confirm the install worked by checking the version:

tmux -V

tmux 3.4

Step 2: Start a named session

The new -s part creates a session with a name you choose, here work. You are now inside it, and it looks like an ordinary shell. Names make it easier to find the right session later.

tmux new -s work

Run something long inside it so you have a process to protect. The ping command with -c 1000 sends a thousand packets and then stops, which is plenty for a test.

ping -c 1000 example.com

Step 3: Detach and disconnect safely

To leave the session running without closing it, press Ctrl+b, release both keys, then press d for "detach". You return to your normal shell, and the session keeps running on the server. Now you can close your SSH window with a clear conscience.

[detached (from session work)]

Step 4: Reconnect and reattach

tmux ls

work: 1 windows (created Sat Oct 31 09:14:02 2026) [80x24] (attached)

Attach to it by name. You will see your ping still counting, exactly as you left it.

tmux attach -t work

Step 5: Use windows and panes

A session can hold several windows, like tabs, and each window can be split into panes. Every shortcut starts with the prefix, Ctrl+b, pressed first and then released before the next key.

Ctrl+b c creates a new window.
Ctrl+b n and Ctrl+b p move to the next and previous window.
Ctrl+b % splits the window left and right. Ctrl+b " splits it top and bottom.
Ctrl+b arrow key moves between panes.
Ctrl+b [ enters scroll mode so you can read older output. Press q to leave it.

Step 6: Stop a session when you are finished

Type exit in each pane or window to close it. When the last one closes, the session ends. You can also end a session from outside it, by name:

tmux kill-session -t work

This stops every process in the session, including the one that is still running, so only use it when you are done.

Tip: Name sessions after their job, such as deploy, logs, or backup. When you have several sessions, tmux ls becomes a quick map of your server's work.

Careful: Closing your terminal window is not the same as detaching. If you close the window without detaching first, tmux usually keeps the session, but a confirmation prompt or a forced close can end it. Detach with Ctrl+b d when you want to be sure.

Troubleshooting

"no server running on /tmp/tmux-1000/default". No tmux session exists at all. Either you already exited them all, or the server rebooted. Start a new one with tmux new -s work.
"can't find session: work". The name is wrong. Run tmux ls to see the exact names.
Ctrl+b does nothing. Your local terminal may be capturing the key combination. Try again in a different terminal app, or check that you are inside tmux and not in a plain shell.
Sessions disappear after a reboot. tmux does not survive a reboot by default. Anything that must run after a reboot belongs in a systemd service, which is covered in the guide on systemd services.

Next steps

Try starting a long task such as a database backup or a file copy inside tmux, then detach and check on it the next day. For jobs that must run without anyone logged in, or should restart automatically, move them into a systemd service.