Tmux---A Linux Termainal Multiplexer

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In the process of remotely connecting to a server via SSH, we may encounter situations where a command is running but the connection is suddenly interrupted, or we have to disconnect for some reason. However, we want the command to continue running after the connection is closed, and we also want to be able to view its output after reconnecting. In such cases, we can achieve this by using a terminal multiplexer — tmux.

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Basic Concepts

• Session: A tmux instance that carries all content

• Window: Similar to a browser tab

• Pane: Split areas within a window

SSH disconnection and reconnection are handled through a Session. Each Session can contain multiple Windows, and each Window can be split into multiple Panes.

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Installing tmux

Debian / Ubuntu Series

sudo apt update
sudo apt install -y tmux

CentOS 7 / Rocky 8+

sudo yum install -y tmux

Or on newer systems:

sudo dnf install -y tmux

SUSE / openSUSE Series

sudo zypper install tmux

note

On some SUSE 12 systems, tmux cannot be installed. In this case, you can use screen as an alternative, or try installing tmux from source.

Alpine Linux (Common in Container Environments)

apk add tmux

Arch Linux

sudo pacman -S tmux

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Verifying tmux

tmux -V

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Basic Operations

Within a Session, almost all operations in tmux are triggered through a prefix key.

• Default prefix key: Ctrl+b

The key sequence is as follows:

Ctrl+b → release → then press another key

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Session

Creating a Session

All operations are performed within a Session, so we first need to create one.

tmux new -S <name>

This creates a named Session.

tip

It is highly recommended to use -S to create a named Session for easier management. If you don’t want to specify a name, simply run the command without parameters:

tmux

Listing All Sessions

View all currently active Sessions:

tmux ls

Reattaching to a Session

Reconnect (resume) a Session:

tmux attach -t <name>

tip

If there is only one Session, you can use the shorthand:

tmux attach

Detaching from a Session (The Soul of tmux)

Since this operation is performed inside a Session, it requires the prefix key:

Ctrl+b, d

This operation does not close (terminate) the Session. When you need to close an SSH connection, you can detach from the Session using this command.

Closing a Session

When all Windows are closed, the Session will automatically terminate.

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Window

After entering a Session, there is a default Window with index 0. Let’s see how to operate on a Window.

Creating a Window

Ctrl+b c

The index of newly created Windows will increment.

tip

If you have three Windows with indices 0, 1, and 2, and you close window 1, window 2 will still keep its index. When you create a new window afterward, it will take index 1.

Switching Windows

• Next: Ctrl+b n

• Previous: Ctrl+b p

• Specify index: Ctrl+b 0 ～ Ctrl+b 9

tip

The maximum number of Windows is not limited to 9. However, windows beyond 9 cannot be switched to using Ctrl+b + number.

Listing Windows

When there are many Windows, switching sequentially may not be efficient. In this case, you can quickly locate a window from the list.

Renaming a Window

Ctrl+b ,

Give a Window a meaningful name to make it easier to identify during use.

tip

By default, when no command is running, a Window is named after the shell, such as bash, zsh, or fish. If a command is running, the window name will display the running command.

Closing a Window

exit

Typing exit will close the current Window.

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Pane

A Pane allows you to split a window into multiple areas. You can split panes vertically or horizontally, and by repeatedly splitting, you can achieve various layouts.

tip

Pane splitting operations are applied to the current Pane. Each Window has one Pane by default.

Vertical Split

Ctrl+b %

This splits the current Pane into two panes side by side (left and right).

Horizontal Split

Ctrl+b "

This splits the current Pane into two panes stacked vertically (top and bottom).

Closing the Current Pane

Ctrl+b x

tmux will prompt you for confirmation before closing.

Automatic Layout Adjustment

Ctrl+b Space

When you don’t want to fine-tune layouts manually, you can use automatic layouts to save mental effort.

tip

Space refers to the spacebar. Pressing it repeatedly cycles through the 5 built-in tmux layouts.

1. Tiled: Panes are tiled based on quantity. Each row contains as many panes as possible; extra panes go into the last row, and the last pane occupies all remaining space.
2. Even Vertical: All panes are arranged from left to right, each with equal size.
3. Even Horizontal: All panes are arranged from top to bottom, each with equal size.
4. Main Horizontal: One pane is placed at the top, with other panes arranged horizontally below it. The main pane occupies more height.
5. Main Vertical: One pane is placed on the left, with other panes arranged vertically on the right. The main pane occupies more width.

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Copy Mode (Viewing Historical Output)

By default, tmux does not support scrolling with the mouse wheel. To view historical output, you need to enter copy mode.

Ctrl+b [

After entering copy mode, you can scroll using the Arrow keys / Page Up / Page Down.

Press q to exit.

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Killing a Session (Use with Caution)

tmux kill-session -t <name>

It is not recommended to end a Session this way. Once a Session is killed, it cannot be recovered. Please operate with caution. If you want to close a Session, you can close all Windows instead. When all Windows are closed, the Session will exit automatically.

At this point, we have mastered the basic operations of tmux. Wish you a pleasant experience~

Happy hacking!!!

A Word

Rippling with the waves for thousands of miles, where is the spring river without moonlight! — “Spring River, Flower, Moon, Night” · Tang Dynasty · Zhang Ruoxu

Details

Full Text

The spring river tides rise to meet the sea,
On the sea the bright moon rises with the tide.
Rippling with the waves for thousands of miles,
Where is the spring river without moonlight!
The river winds around fragrant islets,
Moonlight on flower forests looks like falling frost.
In the empty air, flowing frost seems unseen,
On the shoals, white sand cannot be discerned.
River and sky merge in one pure hue,
A solitary bright moon hangs in the vast sky.
Who by the river first beheld the moon?
In what year did the moon first shine upon mankind?
Life passes on generation after generation,
Yet the river moon looks the same year after year.
I wonder whom the river moon awaits,
Only seeing the long river sending flowing waters away.
A single cloud drifts leisurely,
Endless sorrow at Green Maple Islet.
Who tonight is the boatman adrift?
Where is the longing at the moonlit tower?
Pitifully the moon lingers over the tower,
Shining on the mirror stand of the departed.
Through jade doors and curtains it cannot be rolled away,
From washing stones it brushes past again.
At this moment we gaze at each other but cannot hear,
I wish to follow the moonlight and shine upon you.
Wild geese fly far, yet their light does not pass,
Fish and dragons leap, water forming patterns.
Last night I dreamed of falling flowers by a quiet pool,
Pitiful that spring is half gone and I have not returned home.
The river carries spring away, soon to be gone,
The moon sinks westward over the river pool.
The slanting moon sinks deep into sea mist,
Endless roads toward Jieshi and Xiaoxiang.
Who knows how many return by moonlight?
The setting moon stirs emotion across the river trees.