Tmux (Terminal Multiplexer) is a powerful tool that allows you to create multiple terminal sessions within a single window.
This is particularly useful when working on HPC clusters through interactive sessions on a compute node.
Tmux (Terminal Multiplexer) allows you to create multiple terminal sessions within a single window.
This functionality can come in handy when working on the compute nodes, through an interactive session.
It is very common to need multiple terminal windows, e.g. you have your task running in one terminal, and monitor its activity from another.
Users commonly need multiple terminal windows, e.g. you have your task running in one terminal, and monitor its activity from another.
Tmux allows you to achieve this functionality, through a single interactive session on a node.
### Keywords to know
Before diving in, let's understand some essential Tmux terminology:
Before getting started, let's understand some common Tmux terminology:
-**Session**: A group of windows that can be attached (viewed) or detached (running in background)
-**Window**: Like tabs in your browser, each containing one or more panes
-**Pane**: Split sections within a window
-**Prefix**: The key combination that tells Tmux you're about to enter a command (default: `Ctrl+b`)
We will further clarify these terms through the image attached below.
## Getting Started
To create a new Tmux session:
Tmux is already available on the compute nodes, so you can go ahead and create a new **Tmux session** using:
```bash
tmux new -smy_session
tmux new -syour_session_name
```
When you create a new session, you'll automatically be attached to it. You'll notice a green status bar appear at the bottom of your terminal. The bottom-left corner shows your session name (in this case, "my_session"), which helps you keep track of where you are.
When you create a new session, you'll automatically be attached to it. You'll notice a green status bar appear at the bottom of your terminal. The bottom-left corner shows your session name (in this case, "your_session_name"), which helps you keep track of where you are.
Looking at the image above, we can see how Tmux organizes your workspace. The window is divided into multiple panes (numbered 0, 1, and 2), and each pane operates as an independent terminal. The green dividing lines help you visually distinguish between panes, while the status bar at the bottom provides important session information.
Looking at the image above, we can see how Tmux organizes your workspace. The window is divided into multiple panes (numbered 0, 1, and 2), and each pane operates as an independent terminal.
The green dividing lines help you visually distinguish between panes, while the status bar at the bottom provides some session information.
### Basic Navigation and Control
...
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@@ -57,17 +63,26 @@ For example, to detach from your current session:
2. Release both keys
3. Press `d`
This detaches you from the session while leaving everything running in the background. Once detached, if you want to completely remove a session, you can use:
This detaches you from the session while leaving everything running in the background.
This is one of the most beautiful features about terminal multiplexers, as you can detach from the session
and even disconnect your SSH connection, but your tasks running within the Tmux session in the background.
Once detached, if you want to completely remove a session (which also terminates running tasks through that session), you can use:
As shown in the image, each pane can run its own commands independently. This is incredibly useful when you need to monitor multiple processes or work with different directories simultaneously.
As shown in the image, each pane can run its own commands independently.
This is useful when you need to monitor multiple processes or work with different directories simultaneously.
The numbers on each pane where shown using `Ctrl+b` then `q`, which flashes the number of each pane.
We will further use these numbesr to demonstrate an example of swapping the placement of panes 0 and 2.
### Creating and Managing Panes
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@@ -75,6 +90,12 @@ To split your window:
- Press `Ctrl+b`, release, then press `"` for a horizontal split
- Press `Ctrl+b`, release, then press `%` for a vertical split
To kill a pane:
- Press `Ctrl+b`, release, then press `x` (This kills the running children tasks within that pane as well)
Zooming in/out of a pane:
- Press `Ctrl+b`, release, then press `z` (Toggles between zooming in/out of a pane)
### Navigating Between Panes
Moving between panes is straightforward:
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@@ -84,7 +105,7 @@ Moving between panes is straightforward:
To quickly identify panes:
1. Press `Ctrl+b`, release
2. Press `q`
This will briefly display large numbers in the middle of each pane, as shown in the image above (containg the numbers)
This will briefly display large numbers in the middle of each pane, indicating their pane number.
### Resizing Panes
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@@ -98,38 +119,63 @@ Resizing panes is done using a continuous key combination:
The image demonstrates entering a command to swap two panes. This is just one example of what you can do in command mode - from renaming windows to adjusting layouts. The yellow command bar is where you'll type these commands after pressing `Ctrl+b` followed by `:`.
The yellow command bar is where you'll type these commands after pressing `Ctrl+b` followed by `:`. Once you hit enter, your command will be executed.
### Mouse mode
Now that you know about command mode, you can enter command mode (`Ctrl+b`, release, `:`), and then run:
```
set mouse on
```
to enable clicking between panes, or using your mouse in general to navigate things.
To turn it off:
```
set mouse off
```
### Scrolling Through Pane History
To view previous output in a pane:
1. Press `Ctrl+b`, release
1. Press `Ctrl+b`, elease
2. Press `[` to enter scroll mode
3. Use arrow keys or PgUp/PgDn to navigate
4. Press `q` to exit scroll mode and return to normal operation
3. Use arrow keys, PgUp/PgDn, trackpad, etc to navigate
4. Press `q`or `Ctrl+c`to exit scroll mode and return to normal operation
## Working with Windows
Windows in Tmux work similar to browser tabs. Here's how to manage them:
Each window in Tmux is like a canvas that can be subdivided.
- New window: Press `Ctrl+b`, release, then press `c`
- New window: Press `Ctrl+b`, release, then press `c`. This **c**reates a new window and switches to it.
- Switch windows:
- Next window: `Ctrl+b`, release, then `n`
- Previous window: `Ctrl+b`, release, then `p`
- Specific window: `Ctrl+b`, release, then type the window number
- Rename current window: `Ctrl+b`, release, then press `,`
- Delete a window (This kills the tasks running within its pane(s)):
-`Ctrl+b`, release, then `&`, then press `y` to confirm when prompted.
## Important Notes
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@@ -144,3 +190,15 @@ To cleanly exit Tmux, you can either:
```
kill-session
```
## Fun little things
- You can do Prefix + `t` to turn a pane into a digital clock
- You can sync all panes in a window to send the same command to them all simultaneously. In tmux's command mode (indicated below using `:`), run:
