Alacritty Settings

A simple explanation (refresher) as to the decisions when configuring alacritty on my own machine. Alacritty is an open-source GPU-accelerated terminal emulator.

Why Alacritty?

My motto when it comes to workflows (this goes beyond just software dev) is that we should always iterate on what we do every day, and under this presumption, I realized that thinks that come from the Linux community, developers and ideologies really vibe with me in the sense of being fast, concise, and practical.

Alacritty is open source, meaning that it is bound to have tons of ideas applied to it, for the sake of making it fun. With this as a basis, based on its record of well-behaved and reasonal community building, I picked it due to its sheer speed (thanks to the fact that you get to compile it for your machine specifically), and overall adherence to common linux practices (that are somewhat of the basis of modern DevOps and overall software in general).

Hacking for the vibes

One thing that I did come across here is the fact that Alacritty has not a “background image” type of function. But by being a bit clever I managed to achieve what I wanted. You just have to make Alacritty transparent and reduce opacity a bit (more on that in the settings section).

Settings rundown

[terminal]
shell = { program = "/usr/bin/tmux", args = ["new-session", "-A", "-s", "main"] }

[window]
opacity = 0.8

[keyboard]
bindings = [
  # New "tab"
  { key = "T", mods = "Control|Shift", chars = "\u0002\u0014" },

  # Navigate tabs
  { key = "Left", mods = "Control|Shift", command = { program = "/usr/bin/tmux", args = ["previous-window"] } },
  { key = "Right", mods = "Control|Shift", command = { program = "/usr/bin/tmux", args = ["next-window"] } },

  # Jump to tab N
  { key = "Key1", mods = "Control|Alt", command = { program = "/usr/bin/tmux", args = ["select-window", "-t", "0"] } },
  { key = "Key2", mods = "Control|Alt", command = { program = "/usr/bin/tmux", args = ["select-window", "-t", "1"] } },
  { key = "Key3", mods = "Control|Alt", command = { program = "/usr/bin/tmux", args = ["select-window", "-t", "2"] } },
  { key = "Key4", mods = "Control|Alt", command = { program = "/usr/bin/tmux", args = ["select-window", "-t", "3"] } },
  # ... add 3–9 if you want more
]

In short:

Terminal

We are relegating all the terminal work to tmux. Alacritty simply displays it.
We open the tmux session as a new session. However, if it finds a previous session it will attach to it (effectively making so that we can open up things where we left off)
The name of the session for attaching and for creation will be main

Window

By setting the opacity of Alacritty to 0.8 we allow for the background to show, and in my specific setup (after you set a nice wallpaper like the one on the repo) it will give the idea that the terminal has a background.

Keyboard

Specific hotkeys so that I can move between different windows all managed by tmux. We create new “tabs” with Ctrl + T. There’s a bit to say as to how this setup actually makes everything work, so please read in regards to the bridge.
We can navigate from left to right between tabs with Ctrl + Shift + <Arrow>.
We can jump directly to specific tabs by their order with Ctrl + Alt + <Number>.

The alacritty and tmux bridge

The way that I chose to sort of establish new key bindings that in turn might leverage some function in tmux was to literally catch the key combinations at the alacritty level and then forward something else to tmux.

A short example

We’ll take the new window key binding in alacritty.toml as an illustrative example:

  { key = "T", mods = "Control|Shift", chars = "\u0002\u0014" },

In this instance to the combination of Ctrl + Shift + t we are then making alacritty forward some specific bytes to the terminal (tmux). In this instance:

\u0002 translates to Ctrl + b which is tmux’s default prefix for possible extra extended hotkeys.
\u0014 translates t0 Ctrl + t which is actually the specific binding on tmux’s side that will trigger its new-window function with an extra parameter that will allow for the new session to open up on the active session’s path.

As you can see, it’s a small system in which Alacritty captures combinations, and then forwards a much simpler signal to tmux so that it grabs it and runs something on its side. This is the anatomy of how we should configure things and how everything else will be made.

Small big note: Some sources might treat the chars as x02 or x04, but for my specific instance, alacritty didn’t recognize the characters so I’m using the translated equivalents in unicode.

A small tip

Alacritty by default should detect changes in its .toml config the moment you save the file. So the moment you want to test something out it should be applied automatically, in case of errors as well it will show a red screen and will fallback to a no settings state.

The Alacritty desktop entry

In case we install alacritty with cargo, the executable won’t be available globally hence both we should add cargo’s path to .zshrc, and we should also somehow patch the cargo bin to GNOME’s scanned binaries.

cargo installed binaries are always at ~/.cargo/bin/. And a DE such as GNOME in order to detect executables/binaries, it will look at at two paths:

/usr/bin
/usr/local/bin

What now?. Pretty simple, by being a bit clever we can take advantage of the symlink feature that exists in Linux. Which are basically files that are a dummy in a way, that when queried will bounce the caller back to another file/ executable. And so by running:

sudo ln -s ~/.cargo/bin/alacritty /usr/local/bin/alacritty

We will in essence create an unnoficial executable at a path that GNOME scans but when trying to call it it will directly bounce back to the actual executable. (Which is pretty sweet)

After applying this, we should get the Alacritty desktop entry available and when opening it we should have a blazingly fast terminal emulator ready for use.

NOTE: There’s a utility that allows to pipe a .desktop file to it to see if it’s at the very least formatted correctly: desktop-file-validate <file-path>.