Use "tmux" as terminal multiplexer within "WezTerm" - a shell supporting 24-bit colors

Last year, I switched from Arch Linux to macOS on my desktop - I’m still in the process of improving my macOS setup.

Having been a Linux user for years, I’m comfortable doing most of my tasks within the shell. However, I appreciate having the option to use high-quality paid software, which macOS as an operating system offers me. In addition to learn new things for work, I also develop software for myself.

I tried some development environments to support my software development process, e.g. VS Code, but I missed “vim” and its short, one-character commands a lot.

Being interested in “neovim,” I gave it a try and failed — at first. The visual experience was a total disaster, and I was quite disappointed in myself: I was not able to get a usable color scheme working. Then I became aware of “Terminal.app”’s missing 24-bit color support - nothing I expected to be missing in 2024. It was some kind of a “facepalm” moment for me. After finding out the root cause, I tried different terminal applications, like “Kitty” and “Alacritty.” In the end, I decided to use “WezTerm.”

• Kitty: To much flexibility with regard to the configuration I don’t require for now
• Alacritty: On every upgrade I need to change the “com.apple.quarantine” attribute with xattr -dr com.apple.quarantine /Applications/Alacritty.app.

None of this was true for “WezTerm”. Besides that, it’s an actively and well-maintained project built on top of a compiled language — “Rust”. Being a ’tmux’ user for years, I don’t want to retrain my fingers to learn new shortcuts. Because of this, I tried to get “tmux” working as a terminal multiplexer within “WezTerm”. My first attempts failed with a fast-exiting “WezTerm” and no error message.

For that reason, I started the “WezTermin.app” with logging enabled from within the “Terminal.app.” This revealed the cause of the failure: The command string could not be interpreted by my favorite shells - “bash” and “zsh”.

$ # Starting the "WezTerm.app"
$ WEZTERM_LOG=debug /Applications/WezTerm.app/Contents/MacOS/wezterm

# Error with bash
wezterm_term::terminalstate::performer > perform PrintString("/bin/bash: --: invalid option")

# Error with zsh
wezterm_term::terminalstate::performer > perform PrintString("zsh: bad option string: '-c '-- /opt/homebrew/bin/tmux new-session -As 0''")

After some experiments, I came up with the following working command for the default program configuration of “WezTerm”.

# zsh
config.default_prog = { "/bin/zsh", "-l", "-c", "--", "/opt/homebrew/bin/tmux new-session -As 0" }

# or
# bash
config.default_prog = { "/bin/bash", "-l", "-c", "--", "/opt/homebrew/bin/tmux new-session -As 0" }

This is my current configuration file for “WezTerm”.

-- Pull in the wezterm API
local wezterm = require("wezterm")

-- This will hold the configuration.
local config = wezterm.config_builder()

-- Start tmux
config.default_prog = { "/bin/zsh", "-l", "-c", "--", "/opt/homebrew/bin/tmux new-session -As 0" }

-- Do not ask for permission to close WezTerm
config.window_close_confirmation = "NeverPrompt"
config.skip_close_confirmation_for_processes_named = { "bash", "sh", "zsh", "tmux" }

config.colors = {
	cursor_bg = "#5c8452",
	cursor_fg = "black",
	cursor_border = "#000",
}

-- Color scheme
config.color_scheme = "Gruvbox Light"

-- Font size: Window
config.font_size = 17.0

-- Font size: Tab bar
config.window_frame = {
	font_size = 17.0,
}

-- Return the configuration to wezterm
return config

Thanks for reading!