True Color (24-bit) and italics with alacritty + tmux + vim (neovim)

alacritty-tmux-vim_truecolor.md

True Color (24-bit) and italics with alacritty + tmux + vim (neovim)

This should make True Color (24-bit) and italics work in your tmux session and vim/neovim when using Alacritty (and should be compatible with any other terminal emulator, including Kitty).

Testing colors

Running this script should look the same in tmux as without.

curl -s https://gist.githubusercontent.com/lifepillar/09a44b8cf0f9397465614e622979107f/raw/24-bit-color.sh >24-bit-color.sh
bash 24-bit-color.sh

Configuration files

⚠️ IMPORTANT ⚠️ Don't set $TERM in your shell (zshrc, bashrc, etc.), but your terminal (alacritty).

Alacritty

In ~/.config/alacritty/alacritty.yml:

env:
  TERM: xterm-256color

tmux

In ~/.tmux.conf (or ~/.config/tmux/tmux.conf):

set -g default-terminal "tmux-256color"
set -ag terminal-overrides ",xterm-256color:RGB"

# Or use a wildcard instead of forcing a default mode.
# Some users in the comments of this gist have reported that this work better.
#set -sg terminal-overrides ",*:RGB"

# You can also use the env variable set from the terminal.
# Useful if you share your configuration betweeen systems with a varying value.
#set -ag terminal-overrides ",$TERM:RGB"

vim

In ~/.vimrc:

" You might have to force true color when using regular vim inside tmux as the
" colorscheme can appear to be grayscale with "termguicolors" option enabled.
if !has('gui_running') && &term =~ '^\%(screen\|tmux\)'
  let &t_8f = "\<Esc>[38;2;%lu;%lu;%lum"
  let &t_8b = "\<Esc>[48;2;%lu;%lu;%lum"
endif

syntax on
set termguicolors
colorscheme yourfavcolorscheme

neovim

If you use ~/.vimrc for your nvim configuration, use the above vim example because it's fully compatible.

💡 neovim recently (Dec 6th 2023) merged some changes that detects termguicolors automatically, so there's no need to set this in an upcoming release. I'll update this notice with a version once released as a public version. This came with the 0.10 release (May 16th 2024).

In ~/.config/nvim/init.vim

set termguicolors
colorscheme yourfavcolorscheme

Or ~/.config/nvim/init.lua:

vim.o.termguicolors = true
vim.cmd'colorscheme yourfavcolorscheme'

Not working correctly ?

Check out the comments below for possible solutions.

And if you found another solution I would really appreciate if you left a comment with instructions and the following information:

• OS/Distro + version
• Vim or Neovim + version
• Terminal name + version

Mentions

Shout-out to the nice folks that provided insightful feedback:

• @mikeslattery native neovim termguicolors support
• @mikeslattery black and white vim colorscheme
• @sahibalejandro env variable inside tmux configuration
• @wonbinbk wildcard in tmux terminal configuration

~/.tmux.conf

# Включение поддержки true color
set -g default-terminal "xterm-256color"
set -ga terminal-overrides ',xterm-256color:Tc'

# Включение поддержки мыши
set -g mouse on

~/.config/alacritty/alacritty.toml

[terminal.shell]
program = "tmux"
args = []

[env]
# Без этого в tmux true color не работает
TERM = "alacritty-direct"

~/.config/vim/vimrc

" Используем 20-битные цвета
set termguicolors

OSX Ventura Alacritty 0.12.2 tmux 3.3a nvim 0.9.2

Problem

When using neovim within tmux, my colors were off and it would not display italics or undercurls.

Solution

I had trouble with the provided solution, but it pointed me in the right direction. This is what works for me.

alacritty

I left the env: section commented out

tmux.conf

set-option -sa terminal-features ',alacritty:RGB'
set-option -ga terminal-features ",alacritty:usstyle"
set-option -ga terminal-overrides ',alacritty:Tc'
set -g default-terminal "alacritty"

nvim

termguicolors = true

MacOS Monterey use this setting and work! Thank man

echo 'set -as terminal-overrides ",'"$(echo ${TERM%%-*})"'*:Tc"' >> ~/.tmux.conf

https://github.com/tmux/tmux/wiki/FAQ#how-do-i-use-rgb-colour

tmux must be told that the terminal outside supports RGB colour. This is done by specifying the RGB or Tc terminfo(5) flags. RGB is the official flag, Tc is a tmux extension.
With tmux 3.2 and later this can be added with the terminal-features option:
set -as terminal-features ",gnome*:RGB"
Or for any tmux version the terminal-overrides option:
set -as terminal-overrides ",gnome*:Tc"

and replace gnome with the result of echo ${TERM%%-*} (the first part of $TERM delimited by -) from the terminal emulator that you are currently using outside tmux such as putty or xterm.

I've tried everything else in this thread, this was the only thing that solved it for me running Ubuntu 22.04.5 LTS with tmux 3.2a and neovim v0.10.0-dev. Bless your beautiful shell skills!

Thanks alot for this, it worked! 😄

Fedora 41, Alacritty 0.14.0, tmux 3.5a, nvim 0.10.2

What worked for me was @ericragsdale solution:

alacritty:
nothing in the env section

tmux.conf:

set-option -sa terminal-features ',alacritty:RGB'
set-option -ga terminal-features ",alacritty:usstyle"
set-option -ga terminal-overrides ',alacritty:Tc'
set -g default-terminal "alacritty"

thanks!

@bogdanp05 I use the exact same software versions as you (Fedora, Alacrity, tmux, nvim). The default solution ITT worked for me.