`tmux` to support long running terminal sessions¶

When you connect to the cluster via SSH, your session is tied to that connection — if it drops, any running processes are lost. tmux (terminal multiplexer) solves this by running a persistent session on the login node that survives disconnections. It also lets you split your terminal into multiple panes and windows within a single SSH connection.

Note

The figure above gives an overview of how tmux sits between your SSH client and your shell processes on the login node.

Managing sessions¶

Open a new session¶

Always give your session a descriptive name so you can identify it later:

tmux new -s mysession

Detach from a session¶

Detaching leaves the session (and anything running inside it) alive on the server. You can safely close your terminal after detaching.

Action	Keybind
Detach from current session	`Ctrl`+`B` then `d`

List your sessions¶

tmux ls

Attach to an existing session¶

tmux attach -t mysession

If you only have one session running, tmux attach alone is sufficient.

Kill a session¶

When you are done and no longer need the session:

tmux kill-session -t mysession

Scrolling¶

By default, the scroll wheel does not work inside tmux. You need to enter copy mode first:

Action	Keybind
Enter copy mode	`Ctrl`+`B` then `[`
Scroll up	`Up` / `Page Up`
Scroll down	`Down` / `Page Down`
Exit copy mode	`q`

Multiplexing — windows and panes¶

tmux lets you split a single session into multiple panes (splits within one view) and windows (separate tabs).

Panes¶

Action	Keybind
Split horizontally (top/bottom)	`Ctrl`+`B` then `"`
Split vertically (left/right)	`Ctrl`+`B` then `%`
Close current pane	`Ctrl`+`B` then `x`

Windows¶

Action	Keybind
New window	`Ctrl`+`B` then `c`
Next window	`Ctrl`+`B` then `n`
Previous window	`Ctrl`+`B` then `p`
Switch to window by number	`Ctrl`+`B` then `0`–`9`
Close current window	`Ctrl`+`B` then `&`

Navigating between panes¶

Action	Keybind
Move to pane (arrow keys)	`Ctrl`+`B` then `Up` / `Down` / `Left` / `Right`
Cycle through panes	`Ctrl`+`B` then `o`

Typical multiplexing workflow

A common pattern on the cluster is to open one pane for an interactive srun job, a second pane to monitor it with squeue or nvidia-smi, and a third for editing scripts — all within a single detachable tmux session.

Troubleshooting¶

"sessions should be nested with care, unset $TMUX to force"

This warning appears when you run tmux new -s <name> from inside an existing tmux session

If you're unsure whether you're already inside tmux, check with following command : ( Or check the for green strip on the bottom of the terminal),
```
echo $TMUX
```
A non-empty value means you're in an active session.

tmux to support long running terminal sessions¶