tmux Config: Understanding the Configuration File + Customization Examples

tmux is a popular terminal multiplexer that lets you run multiple sessions inside a single window. What is more, users can easily switch between these sessions, detaching or reattaching them. 

Besides features that tmux offers by default, you can customize it further to suit your projects.

In this tutorial, we’ll explain how exactly you can benefit from customizing tmux and review its config options.

Download comprehensive tmux cheat sheet

tmux Config File 

You can configure the tmux environment with the help of a system configuration file. To use it, log in to your hosted virtual server via SSH and create the tmux.conf file. You can do so via PuTTY SSH. Then, add the preferred configuration commands to it.

Alternatively, you can easily connect to SSH via our browser-based terminal, eliminating the need for additional software:

Note that configuration can be either global or local, depending on the file’s location. If you need a local configuration file, create it in the home directory using the Linux touch command:

touch ~/.tmux.conf

On the other hand, if you want to make a global tmux configuration file, place it in the /etc directory:

touch /etc/tmux.conf

Now, add the preferred configuration to the tmux.conf file. After that, save the file and exit the text editor. The changes will take effect the next time you launch tmux.

tmux Configuration Options

tmux has several key bindings and functions that may not suit all users. By configuring tmux, you can customize key bindings and different functions to align with your workflow and preferences.

In addition to key bindings and options, you can change your tmux terminal’s appearance. For example, customize its color scheme or set a background color.

Lastly, users can set up custom scripts or commands to run when tmux starts. This can be useful for personal development environments, helping you automate certain tasks and ensuring you won’t lose any work.  

Let’s take a deeper look at the three main configuration categories:

Server and Session Options

You should set server options when starting the tmux server, as they affect all sessions. Examples of server options include:

• Default terminal type
• Maximum number of sessions
• Location of the socket for connecting to the tmux server

Use the set-option -s command to apply server options. 

Meanwhile, session options affect the behavior of a particular session. Some of the most common session options are:

• Name of the sessions
• Initial working directory
• Default window layout

To set session options, opt for the set-option command.

User Options

With tmux, users can set custom settings, which can modify the pane, window, session, or server options. Keep in mind that all user options are strings and must be prefixed with the @ symbol. Additionally, user options can store custom values from scripts.

Window and Pane Options

tmux provides many configuration options that allow users to customize the appearance of its windows and panes. What’s more, pane options can be inherited from the window options. As a result, users can set any pane option as a window option, and tmux will apply the configuration to all panes.  

tmux Configuration Examples

Let’s look at some of the most popular tmux configuration examples.  

Change the Default Prefix

One of the most important configuration options of tmux is the prefix. The default prefix key binding is Ctrl + B. To send a command to tmux, users need to press Ctrl + B, and then the wanted command.

The prefix key is easily configurable. In this example, we will change the prefix from Ctrl + B to Ctrl + A. To do this, open the tmux configuration file with the preferred text editor:

sudo nano ~/tmux.conf

Then paste the following code:

# Change prefix from 'Ctrl+B' to 'Ctrl+A'
unbind C-b
set-option -g prefix C-a
bind-key C-a send-prefix

Save the changes and start a new tmux session. 

Use the Mouse Mode

The mouse mode lets users use their mouse to interact with tmux windows and panes. Once it is enabled, users can resize windows and panes and scroll through the output of tmux sessions. 

Keep in mind that mouse support is disabled by default. To enable it, open the configuration file:

sudo nano ~/.tmux.conf

Then paste this code and save the changes:

# Enable mouse mode
set -g mouse on

Set Two Prefixes

It’s possible to have multiple prefix keys in tmux. This can be useful if you want to use a different prefix key in various contexts or have a secondary prefix key as a backup. 

To illustrate, we will enable Ctrl + A and Ctrl + B prefixes. Open the configuration file and add the following tmux commands:  

# Enable two prefixes
set-option -g prefix C-a
set-option -g prefix2 C-b

Change the Default Server Behavior

By default, the tmux server will exit when there are no active sessions. To prevent this, you can disable the exit-empty option with the following command:

#Disable exit-empty
set -s exit-empty off

Start Counting Window and Pane Numbers (Base-Index) At 1

When starting tmux, you will notice that both window and pane numbers start from zero, which can be inconvenient and confusing. Luckily, it’s possible to set the base index to start counting from one. Just add the following code to your tmux configuration file:

# Start counting pane and window number at 1
set -g base-index 1
setw -g pane-base-index 1

Turn off Automatic Renaming Globally

Automatic renaming will rename a tmux window using the format specified by the automatic-rename-format option. To turn off automatic renaming globally in tmux, add the following line to the global configuration file:

# Disable automatic renaming
set-option -wg automatic-rename off

Save the changes and start a new tmux session.

Make the Current Pane’s Background White

Use the command below to set the background color of the current pane to white:

# Change the background color to white
set -g window-active-style bg=white

It’s also possible to adjust the pane colors with the following code:

# Change pane colors
set -g pane-active-border fg=red 
set -ag pane-active-border bg=magenta

How to Configure tmux to Allow Copy-Paste Between System and tmux Clipboards

By default, tmux uses its clipboard for copying and pasting text within a session. It means that users cannot paste text copied from tmux to an outside window.

However, it’s possible to configure tmux to allow copy-paste between the system clipboard and tmux clipboard. To do so, consider installing xclip, which enables the communication between the tmux and system clipboards.

Here are the steps to configure tmux to allow copy-paste:

1. Install xclip:

sudo apt-get install xclip

2. Add the following lines to your tmux configuration file:

# Use xclip to copy and paste with the system clipboard
bind C-c run "tmux save-buffer - | xclip -i -sel clip"
bind C-v run "tmux set-buffer $(xclip -o -sel clip); tmux paste-buffer"

This configuration uses C-c to copy the selected text to the system clipboard and C-v to paste from the system clipboard into tmux.

3. Reload your tmux configuration with the following command:

tmux source-file ~/.tmux.conf

After these steps, you will be able to copy and paste text between tmux and the system clipboard. Whenever you press the prefix followed by Ctrl + C, xclip will capture the current tmux buffer. When you want to paste the content, press the prefix followed by Ctrl + V.  

Conclusion

tmux is an excellent tool for any Unix-based server management. Combined with the right configuration options, users can expect to tailor their terminal to match even the highest standards.

In this tutorial, we’ve covered the main tmux configuration categories and provided some helpful configuration examples. Additionally, we’ve gone through the process of installing xclip, which enables copy-pasting data between the system and tmux clipboards. 

If you have any questions or insights, leave them in the comment section below.

tmux Config FAQ

Check out these most frequently asked questions about tmux configuration.