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

Hi guys, I was following the instruction and I hit another problem. When I change

set -g default-terminal "screen-256color"

to

set -g default-terminal "tmux-256color"

The problem is exactly like this: https://stackoverflow.com/questions/45931164/duplicated-characters-and-non-updating-input-using-tmux-in-zsh I don't know why :(

I am also having this issue, any solutions yet?

Not everyone have terminfo "tmux-256color" in /usr/share/terminfo/t/tmux-256color (system-wide) or ~/.terminfo/t/tmux-256color (user only)
So...There is good Guide how to get tmux-256color ------ >>>> https://gist.github.com/bbqtd/a4ac060d6f6b9ea6fe3aabe735aa9d95 ( work for any distro )

Thank you!

good for me. Love you!

set -ag terminal-overrides ",$TERM:RGB"

Thank you!

I only needed to set this one line in my tmux.conf.
Nothing else changed in neither environment variables nor Alacritty config.

Arch Linux, tmux in Alacritty.

Note: When I tried to do this a few times before I might have gotten the solution but I must have missed it because colors didn't update before typing this once and opening a new terminal afterwards: tmux kill-server

Thank you!!!

OSX, Alacritty, ssh'ed to a remote desktop, neovim inside tmux on the remote desktop.

I find that when I press backspace inside tmux, it convert to white space. also the color is also inconsisent outside and inside tmux

MacOS : 12.6
Vim : 9.0
Alacritty : 0.11.0

inside alacritty.yml:

font:
  normal:
    family: Menlo 

  size: 14.0

Inside .vimrc:

set background=dark
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 onedark

Inside .tmux.conf:

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

here is what worked for me
osx 12.1
alacritty 0.11.0
tmux 3.3a

#alacritty.yml 
env:
  TERM: screen-256color

#.tmux.conf
set -g default-terminal "screen-256color"
set -sg terminal-overrides ",*:RGB"

#.vimrc
set termguicolors

I tried every config in this article and still cannot get it to work.

I'm using Arch and Alacritty

however, using the default console works

any ideas?

EDIT: setting enable_rgb: true in alacritty.yml did the trick

@LeFede This worked for me with Arch/Alacritty/tmux

alacritty.yaml

env:
  TERM: alacritty-direct

tmux.conf

set-option -a terminal-overrides ",alacritty:RGB"

default-terminal was not needed in the tmux.conf

@LeFede This worked for me with Arch/Alacritty/tmux

alacritty.yaml

env:
  TERM: alacritty-direct

tmux.conf

set-option -a terminal-overrides ",alacritty:RGB"

default-terminal was not needed in the tmux.conf

thank you

None of these work for me on alacritty..

Same stuff every time I try to adopt tmux. Spend an hour trying everything on the internet.

Clipboard is a PITA, OSC52 support doesn't work.
Colors don't work.
Mouse scrolling doesn't work.

It's absurd this tool is so evangelized.

When following these instructions and changing the tmux config, I found that my backspace key created space characters.

this was resolved after restarting tmux server

tmux kill-server

hope this help anyone, thank you for this awesome gist!

--
macOS (11.7.8)
NVIM (0.9.1)
alacritty (0.11.0)
tmux (3.3a)

Fedora 38, Konsole + TMux 3.3a + neovim 0.9.1 .
The following worked for me:

set -sa default-terminal "screen-256color"
set -sa terminal-features ",xterm-256color:RGB"

Notably, I could NOT have tmux-256color as my default terminal even though I downloaded it off the internet and so I know I had it on hand. It had to be screen.

Not everyone have terminfo "tmux-256color" in /usr/share/terminfo/t/tmux-256color (system-wide) or ~/.terminfo/t/tmux-256color (user only) So...There is good Guide how to get tmux-256color ------ >>>> https://gist.github.com/bbqtd/a4ac060d6f6b9ea6fe3aabe735aa9d95 ( work for any distro )

A little Ai model told me you can use infocmp xterm-256color to check if you have this (the paths quoted above were blank, but infocmp found the terminfo here /lib/terminfo/t/tmux-256color (ubuntu 22.04)

This solved my issue as well thanks 😊

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

I find that when I press backspace inside tmux, it convert to white space. also the color is also inconsisent outside and inside tmux

MacOS : 12.6
Vim : 9.0
Alacritty : 0.11.0

inside alacritty.yml:

font:
  normal:
    family: Menlo 

  size: 14.0

Inside .vimrc:

set background=dark
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 onedark

Inside .tmux.conf:

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

@sokinpui The phenomenon I encountered before is the same as yours. You can try this set of configurations. It works for me.

alacrity

env:
  TERM: screen-256color

tmux

set -g default-terminal "screen-256color"
set-option -sa terminal-overrides ',screen-256color:Tc'

Hey 👋
This combination of settings works fine for me

# .alacritty.yml

env:
  TERM: alacritty

and in my tmux config:

# tmux.conf

set-option -g default-terminal "screen-256color"

• OS/Distro: MacOS Ventura 13.6
• Vim: VIM - Vi IMproved 9.0
• Terminal: alacritty 0.12.3 (5efb069)
• Tmux: tmux 3.3a

Hope it can help ✌️

Alacritty versions >= 0.13.0 (moved to TOML for config)

[env]
TERM="xterm-256color"

Italics in my vim were messed up, if someone has this problem, you can verify by running

echo -e "\e[3mitalic\e[0m"

if output is in italics then it's a vim problem, otherwise something else is wrong.

I had to add the following in my vimrc as per this for italics.

let &t_ZH="\e[3m"
let &t_ZR="\e[23m"

using macvim, tmux and iterm2

Thank you so much for this..

I legit switched to kitty for months over this issue, I had tried every fix out there (what did it was the ENV) so glad to be back with alacritty

AMAZING!!! Thanks

BREAKING NEWS!

(edits: I was wrong. Only the neovim changes aren't necessary.)

tl;dr - This gist is no longer necessary with latest Neovim.

Neovim now checks for 256 color compatibility and automatically sets termguicolors. Alacritty with default $TERM value ("alacritty") works fine. I just tested it with nightly.

Recent changes announced at the Neovim conference a few days ago have made the changes in this gist unnecessary for latest builds. However, I'm sure as of this moment many people are using versions that don't yet support this and that will likely be the case for a few weeks. I don't know the exact version this was added, or which versions have it other than latest nightly.

Of course, it will still be necessary for Vim.

Thanks for the heads-up @mikeslattery ! This is great news :)

I'll update this article and follow up when this goes into a public release.

Looks like I wasn't correct. You still need the tmux and alacritty config. You just don't need the neovim config anymore.

Quick test for Linux. As of this comment it works for nightly and not for release.

#!/bin/bash
# Test for truecolor.  Should see bands of smooth gradient colors.

# To test  installed nvim, set this to "nvim" and comment out #linux nvim install block, and remove rm $NVIM line
NVIM=/tmp/nvim

# Linux nvim install
NIGHTLY=https://github.com/neovim/neovim/releases/download/nightly/nvim.appimage
RELEASE=https://github.com/neovim/neovim/releases/download/stable/nvim.appimage
# Change to $NIGHTLY to see it working correctly.
curl -Lo $NVIM $RELEASE
chmod +x $NVIM

# Reconfigure
echo '
set -ag terminal-overrides ",xterm-256color:RGB"
' > /tmp/.tmux.conf
echo '
env:
  TERM: xterm-256color
' > /tmp/alacritty.yaml

# Test
TEST=https://gist.githubusercontent.com/lifepillar/09a44b8cf0f9397465614e622979107f/raw/24-bit-color.sh
alacritty --config-file /tmp/alacritty.yaml \
  -e tmux -f /tmp/.tmux.conf -L nvim new-session \
  $NVIM --clean  "+terminal curl -s $TEST | bash" "+set termguicolors?"
# old way:
# $NVIM --clean  +"set termguicolors" "+colorscheme ron" "+terminal curl -s $TEST | bash"

# Cleanup
rm "$NVIM"
rm /tmp/.tmux.conf /tmp/alacritty.yaml

Appreciate the detailed follow-up on this @mikeslattery. I've updated the article to reflect this 👍

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.

Just what I needed, thank you a lot.

My configuration:

alacritty 0.13.2
NVIM v0.9.5

.tmux.conf

# Fix Colors
set -g default-terminal "screen-256color"
set -ag terminal-overrides ",xterm-256color:RGB

alacritty.toml

[env]
TERM="xterm-256color"

config neovim

vim.opt.termguicolors = true