As I’ve fallen more down the rabbit hole, empowered by nix making it so easy to install, configure and manage any software, I discovered Alacritty as a fast, configurable terminal emulator. I’ve used and enjoyed iTerm2 for a while but it never hurts to try something new. I have some muscle memory built up for how my use my machine, so my aim was to configure something I could use comfortably in Alacritty, modeling it off of my iTerm setup.

What went well

  • Replicating my iTerm tmux pane creation, switching, and maximizing. After a bit of time, I mapped my existing iTerm keybindings to the proper tmux commands to reproduce nearly an identical experience.
  • Starting a tmux session when Alacritty starts. This allows me to quit the Alacritty without losing my layout or anything that is running. I can also attach to it from any other terminal.
  • Configuration for version control. It’s all in ~/config/alacritty/alacritty.toml.
  • Color configuration. It just works in the config.
  • Nerdfonts. These just worked too.
  • ⌘k, ⌘+, ⌘-, ⌘=, ⌘0 (to clear, resize and resize text size) all work the same way as iTerm by default, so that was a nice surprise.
  • Mouse navigation. I’ve become used to being able to using the mouse to scroll up through the history of a pane’s output. By default, tmux scrolls through the command history. You need to enter copy-mode with ctrl+b [ for the mouse to be usable to scroll, then q to exit this mode and return to the command prompt. However, I was able to match the behavior I’m used to by adding set -g mouse on to ~/.tmux.conf. I eventually pulled this out into my nix home-manager setup with a few other quality of life improvements, like inactive pane dimming.
programs.tmux = {
    enable = true;
    aggressiveResize = true;
    shell = "${pkgs.zsh}/bin/zsh";
    terminal = "tmux-256color";
    historyLimit = 100000;
    mouse = true;
    extraConfig = ''
    # dim inactive pane
    set -g window-style 'fg=color8,bg=default'
    set -g window-active-style 'fg=color7,bg=default'

This config also allows for pane selection by clicking and selection within a single pane. Pretty nice.

What could be better

  • Pane closing. I don’t like having to confirm a pane close with y, but it’s probably for the best because one day it will save me from losing something.
  • ⌘f for find is different, not necessarily worse. I will have to see.

This is the alacritty.toml after my initial effort:

live_config_reload = true

# start zsh then attach to a consistent tmux session that lives beyond quitting the app
program = "/etc/profiles/per-user/danielcorin/bin/zsh"
args = ["--login", "-c", "tmux new-session -A -s main-alacritty"]

size = 14.0

# installed via nix
family = "Hack Nerd Font Mono"
style = "Bold"

family = "Hack Nerd Font Mono"
style = "Italic"

family = "Hack Nerd Font Mono"
style = "Regular"

family = "Hack Nerd Font Mono"
style = "Italic"

# sublime text monokai
black = "#666666"
red = "#f92672"
green = "#A6E22E"
yellow = "#e2e22e"
blue = "#819aff"
magenta = "#AE81FF"
cyan = "#66D9EF"
white = "#f8f8f2"

black = "#333333"
red = "#C4265E"
green = "#86B42B"
yellow = "#B3B42B"
blue = "#6A7EC8"
magenta = "#8C6BC8"
cyan = "#56ADBC"
white = "#e3e3dd"

cursor = "0xd8d8d8"
text = "0x181818"

# highlight copies text, only really useful when a pane is in full screen unless selection isn't multi-line
save_to_clipboard = true

decorations = "Full"
dynamic_padding = true
dynamic_title = true

# the default padding
x = 2
y = 2

# vertical, slightly thickened cursor
style = "Beam"
unfocused_hollow = false
thickness = 0.2

bindings = [
    # ⌘ + enter puts window in macOS full screen
    { key = "Enter", mods = "Command", action = "ToggleFullscreen"},
    # opt + right and left jump between words
    { key = "Right", mods = "Alt", chars = "\u001BF" },
    { key = "Left",  mods = "Alt", chars = "\u001BB" },
    # ⌘ + d adds a pane to the right (splits window vertically)
    { key = "D",  mods = "Command", chars = "\u0002%" },
    # ⌘ + ⇧ + d adds a pane below (splits window horizontally)
    { key = "D",  mods = "Command|Shift", chars = "\u0002\"" },
    # ⌘ + w prompts you to close the pane, "y" to confirm
    { key = "W",  mods = "Command", chars = "\u0002x" },
    # ⌘ + arrows are for directional navigation around the panes
    # move down a pane
    { key = "Down", mods = "Command", chars = "\u0002\u001b[B" },
    # move up a pane
    { key = "Up", mods = "Command", chars = "\u0002\u001b[A" },
     # move left a pane
    { key = "Left", mods = "Command", chars = "\u0002\u001b[D" }
    # move right a pane
    { key = "Right", mods = "Command", chars = "\u0002\u001b[C" },
    # ⌘ + ⇧ + enter maximizes the pane within the alacritty window
    { key = "Enter", mods = "Command|Shift", chars = "\u0002z" },

Eventually, I ported these to my home-manager config, which creates the ~/.config/alacritty/alacritty.toml for me using nix-darwin.

programs.alacritty = {
    enable = true;
    settings = {
        # ... omitted for brevity

Another nice (terrible?) thing about this project was I learned and remembered a bunch of tmux along the way. My tmux modifier is ctrl+b which is not that nice to type.

  • d: detach
  • ": split horizontal
  • %: split vertical
  • x: close pane with confirmation
  • arrows: navigate between panes

my starting Alacritty terminal setup