v0.17.0 Faster text rendering: printed text to cells in C

Kill it. Crash it.
Your tabs are still there.

guiltty is a Linux-only, GPU-accelerated terminal emulator written in Elixir and C. Every tab is a supervised process tree and the renderer is its own OS process, so when a part crashes, its supervisor restarts it and your tabs stay.

Install guiltty Read the source

you@linux:~/src

╭─ │ ~/src ✔ │ at 16:24:55 ─╮

╰─

milestones implemented: 16; milestones implemented
renderers, the same pixels: 2; renderers, the same pixels
rows of scrollback: 10,000; rows of scrollback
book chapters on how it works: 26; book chapters on how it works

How it works

Elixir does the thinking. C draws the pixels.

Your shell writes bytes into a pseudoterminal. A NIF hands them to the BEAM, where a parser and a screen, plain Elixir processes, turn them into cells. The renderer is a separate program that only draws: if it dies, guiltty starts a new one and your tabs are still there.

Your shell

bash, zsh, fish: your login shell

the BEAM

PTY NIF

C · enif_select

Parser

DEC state machine

Screen

grid, scrollback

Renderer

its own process · Vulkan or GL

Features

A daily driver, with the BEAM underneath.

The things you expect from a modern terminal, and a few that come almost for free with a supervision tree.

Vulkan 1.3, or OpenGL. Same pixels.

guiltty draws with Vulkan by default. No driver? It falls back to OpenGL by itself and says so in the tab bar, and GUILTTY_RENDERER=gl picks one for a run. A test replays recorded frames through both and checks they match, pixel for pixel.

Lockable tabs

Lock a tab and close its window: it keeps running, and the next guiltty brings that window back with it.

Ctrl + Shift + L

Safe broadcast

Type once into every tab in the group. If a connection drops, typing goes nowhere, so a command meant for your servers doesn't land on your own machine.

Ctrl + Shift + B

Unicode, properly

Grapheme clusters, wide characters, HarfBuzz shaping, ligatures, fallback fonts, color emoji and Nerd Font icons that spill into the next cell.

Live config, in Elixir

config.exs is plain Elixir, applied to the open window on save. Mistakes show in red in the tab bar, with a suggestion for misspelled settings.

Full-screen programs

Alternate screen, scroll regions, mouse reporting, bracketed paste, cursor shapes. Tested with vim, less, htop, btop and tmux.

Many windows, one guiltty

Each window has its own tabs, locked tabs and broadcast group. Closing one never touches the others; guiltty stops after the last.

Ctrl + Shift + N

A window in 0.1 s

guiltty is a small client that asks the running guiltty for a window over a private socket, like emacsclient. About 0.1 s with guiltty running, 0.7 s from cold, on the developer's machine.

Measured, then faster

Floods of short lines (seq, logs) land about 3x faster than in v0.13, laid down together and scrolled once. make bench measures it.

Scrollback, search, selection

10,000 rows per tab, searched with Enter and Shift+Enter. Select to copy to the primary selection, middle click to paste. Backpressure from the shell to the screen means a flood of output can't outrun the screen.

[info] worker 3 started

[info] request GET /health 200 in 1ms

[info] worker 4 started

[info] request GET /health 200 in 2ms

GET /health 2 of 48

Self-healing

Go on. Kill something.

A simulation of guiltty's real supervision tree. Click a process to kill it and watch what its supervisor restarts. In the real thing, you'd barely notice.

Each tab is its own rest_for_one tree: Pty, Screen, Parser.
Every window is its own Desk: crash one and the others never notice.
kill -9 the renderer and its Desk starts a new Window. The screen heals.

Processes killed: 0

iex(guiltty@127.0.0.1)1> :observer

Guiltty.Supervisor rest_for_one <0.212.0>
Guiltty.Registry <0.219.0>
Guiltty.Config reloaded on save <0.226.0>
Guiltty.Sessions DynamicSupervisor <0.233.0>
rest_for_one <0.240.0>
the PTY NIF <0.247.0>
<0.254.0>
<0.261.0>
Session.Supervisor 2 <0.268.0>
Guiltty.Desks DynamicSupervisor <0.275.0>
one per window <0.282.0>
significant <0.289.0>
Guiltty.Window the renderer port <0.296.0>
its own OS process pid 9393
Desk 2 <0.310.0>
Guiltty.Lifeline watches the desks <0.317.0>

log

Themes

Built-in themes. Or bring your own.

Pick one by name, or start from one and change single colors. Every terminal on this page follows your pick.

Tomorrow Night is what guiltty uses without a config.

~/.config/guiltty/config.exs

# the last expression is the config
[
  font: [family: "JetBrainsMono Nerd Font", size: 14],
  ligatures: true,
  theme: "tomorrow-nightcatppuccin-mochadraculagruvbox-darksolarized-dark",
  cursor: [style: :block, blink: false],
  renderer: :vulkan
]

Keys

Rebind any of them.

The defaults, as they ship; paste (Ctrl+Shift+V) is the one fixed key. Forgot one? Ctrl + Shift + / opens the cheatsheet, built from your own config.

New window Ctrl + Shift + N

New tab Ctrl + Shift + T

Close tab (asks if busy) Ctrl + Shift + W

Previous tab Ctrl + PgUp

Next tab Ctrl + PgDn

Move tab left Ctrl + Shift + PgUp

Move tab right Ctrl + Shift + PgDn

Rename the tab Ctrl + Shift + R

Scroll back Shift + PgUp

Clear the scrollback Ctrl + Shift + K

Search the scrollback Ctrl + Shift + F

Copy Ctrl + Shift + C

Paste Ctrl + Shift + V

Zoom in Ctrl + =

Zoom out Ctrl + -

Reset zoom Ctrl + 0

Open the config file Ctrl + ,

The cheatsheet: every key Ctrl + Shift + /

Lock the tab 🔒 Ctrl + Shift + L

Broadcast tabs Ctrl + Shift + B

Install

Built on your machine. Runs without Elixir.

guiltty builds from source, so you need Elixir 1.18+ on Erlang/OTP 26+, and GCC 15+, once. The installed copy carries its own Erlang runtime and needs no root.

1 What to install first

shell

sudo zypper install gcc make pkg-config SDL3-devel freetype2-devel \
  fontconfig-devel harfbuzz-devel vulkan-devel shaderc elixir erlang-epmd

The one guiltty is developed on.

shell

sudo dnf install gcc make pkgconf-pkg-config SDL3-devel freetype-devel \
  fontconfig-devel harfbuzz-devel vulkan-loader-devel vulkan-headers glslc elixir

If Fedora's Elixir is older than 1.18 (elixir --version), leave out elixir and get Elixir and Erlang from asdf.

shell

sudo apt install build-essential pkg-config libsdl3-dev libfreetype-dev \
  libfontconfig-dev libharfbuzz-dev libvulkan-dev glslc elixir erlang-dev

Older Ubuntus have neither SDL3 nor GCC 15.

shell

sudo pacman -S --needed base-devel sdl3 freetype2 fontconfig harfbuzz \
  vulkan-icd-loader vulkan-headers shaderc elixir

Everything is in the official repositories.

Only openSUSE has been tried; the other package names come from each distribution's package listings.

Tested Elixir and Erlang/OTP

The minimum is Elixir 1.18 on Erlang/OTP 26. Older versions aren't supported.

Elixir	Erlang/OTP	Status
1.20.4	29	Developed on
1.19.7	28	Builds, tests pass
1.19.7	26	Builds, tests pass
1.18.4	26	Builds, tests pass

2 Clone it and run the installer

shell

git clone https://github.com/z7ealth/guiltty.git
cd guiltty
./install.sh

Update


                  
                  
                    git
                  
                    pull
                  
                    &&
                  
                    ./install.sh

Uninstall


                  
                  
                    ./install.sh
                  
                    --uninstall

Elsewhere


                  
                  
                    PREFIX=/opt/guiltty
                  
                    ./install.sh

3 Run it

Type guiltty or find it in your applications menu. It needs a GPU with OpenGL 3.3, and draws with Vulkan where there's a 1.3 driver. It looks best with a Nerd Font, Noto Color Emoji and a font for Chinese, Japanese and Korean.

Read the docs: keys, settings, themes

The build

Implemented in milestones.

Each version is one milestone of the build plan, from the first byte through a PTY to tab comforts. The devlog tells how each one went.

0.1
First light
Oct 29

The whole pipeline: a PTY NIF, a parser, the screen in Elixir and an OpenGL renderer. ASCII only, 80×24.
0.2
Color
Oct 29

16, 256 and 24-bit color, Paul Williams' DEC parser, and a resizable window.
0.3
The vim fight
Oct 29

Alternate screen, scroll regions, mouse reporting. vim, less, htop, btop and tmux work.
0.4
The BEAM advantage
Oct 29

Tabs, self-healing sessions, detach and reattach, live config, backpressure.
0.5
Daily driver
Oct 30

Unicode, HarfBuzz shaping, color emoji, 10,000 rows of scrollback, search, HiDPI.
0.6
Flat tabs
Oct 30

The flat tab bar, named themes, cursor and window settings, the cheatsheet.
0.7
The installer
Oct 30

./install.sh, a menu entry and the logo.
0.8
Lockable tabs
Oct 30

Lock a tab and it outlives the window.
0.9
Broadcast
Oct 30

Type once into every tab in the group, without typing into your own machine by mistake.
0.10
Vulkan
Oct 30

A Vulkan 1.3 renderer, pixel-for-pixel the same as OpenGL, with automatic fallback.
0.11
Ligatures
Oct 30

With a font that has them, |>, ->, != and === are drawn as one symbol. Cleaner tabs, too.
0.12.4
Security
Oct 30

Hardened C, a localhost-only node with a private cookie, a pidfd for the shell, and titles that can't fake a locked tab.
0.13
Multi window
Oct 30

Several windows, each with its own tabs, locked tabs and broadcast group. Ctrl+Shift+N opens one.
0.14
Performance
Oct 31

Floods of short lines show up 3x faster, startup is 100 ms sooner, and make bench measures it all.
0.15.3
Client and server
Oct 31

guiltty is a small client that asks the running guiltty for a window, like emacsclient: 0.1 s.
0.16.1
Tab comforts and styles
Nov 1

Busy tabs ask before closing, ● and 🔔 mark tabs you're not looking at, tabs can be renamed and reordered, and drawn flat, powerline, rounded, minimal or with separators.

The changelog The devlog

The book

Learn how a terminal works, from the kernel up.

guiltty comes with a book: twenty-six chapters with diagrams, one for every part, from pseudoterminals to tab styles.

Go on, try to break it.

Linux. Tried on openSUSE Tumbleweed, X11 and an AMD GPU; Wayland, Intel and NVIDIA should work but haven't been tried. Open source, MIT licensed.

Install guiltty Star it on GitHub

Kill it. Crash it. Your tabs are still there.

Elixir does the thinking. C draws the pixels.

A daily driver, with the BEAM underneath.

Vulkan 1.3, or OpenGL. Same pixels.

Lockable tabs

Safe broadcast

Unicode, properly

Live config, in Elixir

Full-screen programs

Many windows, one guiltty

A window in 0.1 s

Measured, then faster

Scrollback, search, selection

Go on. Kill something.

Built-in themes. Or bring your own.

Rebind any of them.

Built on your machine. Runs without Elixir.

Update

Uninstall

Elsewhere

Implemented in milestones.

First light

Color

The vim fight

The BEAM advantage

Daily driver

Flat tabs

The installer

Lockable tabs

Broadcast

Vulkan

Ligatures

Security

Multi window

Performance

Client and server

Tab comforts and styles

Learn how a terminal works, from the kernel up.

Go on, try to break it.

Kill it. Crash it.
Your tabs are still there.