Tmux

How to use the tmux set command?

Quick Answer

The set command in tmux is used to configure options during runtime or in your configuration file. Use it with Ctrl+b : followed by set OPTION VALUE. For global options, use set -g, for window options use set -w, and for server options use set -s.

set -g mouse on

Detailed Explanation

The set command is one of the most commonly used commands in tmux, allowing you to configure virtually every aspect of tmux's behavior. It works both in the command prompt during runtime and in your ~/.tmux.conf configuration file.

Basic Set Command Syntax

# Basic syntax
set OPTION VALUE

# Set a global option
set -g OPTION VALUE

# Set a window option
set -w OPTION VALUE
# Or equivalently
set-window-option OPTION VALUE

# Set a server option
set -s OPTION VALUE

The scope flags (-g, -w, -s) determine which level of tmux configuration you're modifying:

Global options (-g) apply to all sessions
Window options (-w) apply to all windows in a session
Server options (-s) apply to the tmux server process

Common Set Command Examples

# Enable mouse support
set -g mouse on

# Set the prefix key to Ctrl+a
set -g prefix C-a

# Set terminal color support
set -g default-terminal "screen-256color"

# Increase scrollback buffer size
set -g history-limit 10000

# Set window numbering to start from 1 instead of 0
set -g base-index 1

# Set pane numbering to start from 1
set -g pane-base-index 1

# Set status bar colors
set -g status-style "bg=black,fg=white"

These examples show some of the most commonly used set commands that tmux users configure.

Using Set During Runtime

You can use the set command during an active tmux session by entering the command prompt:

# Press Ctrl+b followed by : to access the command prompt
# Then type your set command
set -g mouse on

Changes made this way are temporary and will be lost when the tmux server restarts. To make them permanent, add them to your ~/.tmux.conf file.

Toggling Options

For boolean options, you can toggle them on and off:

# Turn on mouse mode
set -g mouse on

# Turn off mouse mode
set -g mouse off

You can create key bindings to toggle options in your configuration:

# Add to ~/.tmux.conf - Press Ctrl+b m to toggle mouse mode
bind m set -g mouse \; display "Mouse mode toggled"

Pro Tip

View the current value of any tmux option with the show-options command:

# Show all global options
Ctrl+b :show-options -g

# Show a specific option
Ctrl+b :show-options -g mouse

This is useful for checking your current configuration or troubleshooting issues.

Setting Multiple Options

For complex key bindings or scripts, you can set multiple options at once using semicolons:

# Set multiple options with one command
set -g status-style "bg=black,fg=white" \; set -g mouse on \; set -g history-limit 5000

Note the backslash before each semicolon when used in a configuration file. When entered at the command prompt, omit the backslashes.

←Back to FAQ Index