EKo — Extended Kilo

A lightweight terminal text editor written in Zig, extended from kilo. EKo adds syntax highlighting for 14 languages, configurable themes, find & replace, file switching, and a piece-table–based text buffer — all in a single dependency-free binary.

Quick Install

No dependencies required — the script downloads the Zig compiler automatically:

curl -fsSL https://raw.githubusercontent.com/nitaystain/eko/main/install.sh | sh

Or clone and run locally:

git clone https://github.com/nitayStain/eko.git
cd eko
./install.sh                       # installs to /usr/local/bin
PREFIX=/usr ./install.sh           # or pick a different prefix

Building from source

If you have Zig (0.15+) installed:

zig build                          # debug build
zig build -Doptimize=ReleaseFast   # optimized build

The binary is placed in zig-out/bin/eko.

Usage

eko <filename>    # open a file
eko               # start with an empty buffer

Keyboard shortcuts

Key	Action
Ctrl-S	Save (prompts for filename if none set)
Ctrl-F	Find (incremental search)
Ctrl-R	Find & Replace (all occurrences)
Ctrl-O	Open / switch to a different file
Ctrl-Z	Undo
Ctrl-Y	Redo
Ctrl-C	Copy selection
Ctrl-X	Cut selection
Ctrl-V	Paste
Ctrl-Q	Quit (press twice to discard unsaved changes)
Ctrl-H / Backspace	Delete character before cursor
Delete	Delete character under cursor
Enter	Insert newline
Home / End	Jump to start / end of line
Page Up / Page Down	Scroll by screen
Arrow keys	Move cursor
Tab	Insert tab (or spaces if expand_tabs is on)

Find mode

While in find mode (Ctrl-F):

Key	Action
Type characters	Build search query (live incremental search)
Enter / → / ↓	Jump to next match
Backspace / ← / ↑	Jump to previous match
Delete	Remove last character from query
Escape	Cancel search and restore original position

Find & Replace

Ctrl-R prompts for a search term and then a replacement string. All occurrences are replaced at once. Press Escape at either prompt to cancel.

Switching files

Ctrl-O prompts for a file path. If the current buffer has unsaved changes you'll be asked whether to save first. The new file is loaded (or an empty buffer is created if the path doesn't exist yet).

Syntax highlighting

EKo highlights 14 languages out of the box:

C/C++, Python, JavaScript/TypeScript, Rust, Go, Shell (Bash/Zsh), JSON, YAML, TOML, Markdown, CSS/SCSS/LESS, HTML/XML/SVG, SQL, and Makefile.

Languages are detected by file extension.

Adding custom languages

Create .syn files in ~/.eko/syntax/:

filetype             = OCaml
filematch            = .ml .mli
comment_single       = (*
comment_multi_start  = (*
comment_multi_end    = *)
flags                = numbers strings
keyword1             = if then else match with fun let in
keyword2             = int string float bool unit

• keyword1 — highlighted as keywords (e.g. control flow)
• keyword2 — highlighted as types (appended with | internally)
• flags — numbers and/or strings to enable literal highlighting
• Multiple keyword1 / keyword2 lines are merged

Configuration

EKo reads ~/.ekorc on startup. The file uses a simple key = value format. Lines starting with # are comments.

Example ~/.ekorc

# Tab behavior
tab_size    = 4
expand_tabs = true

# Color theme
theme       = monokai

# Cursor
# 0=block, 1=underline, 2=beam
cursor_type  = 0
cursor_blink = false

# Override individual colors with hex (#RRGGBB) or 256-color index
# color_comment  = #75715e
# color_keyword1 = #f92672
# color_keyword2 = #66d9ef
# color_string   = #e6db74
# color_number   = #ae81ff
# color_match    = #e6db74
# color_bg       = #272822

Configuration keys

Key	Type	Default	Description
tab_size	integer	4	Width of a tab stop in spaces
expand_tabs	boolean	false	Insert spaces instead of a tab character
smart_selection	boolean	false	Auto-copy mouse-selected text to clipboard
theme	string	default	Color theme name (see below)
cursor_type	integer	0	Cursor shape: 0 block, 1 underline, 2 beam
cursor_blink	boolean	false	Whether the cursor blinks
color_bg	color	-1	Background color (-1 = terminal default)
color_comment	color	6	Comment color
color_keyword1	color	3	Keyword color
color_keyword2	color	2	Type / secondary keyword color
color_string	color	5	String literal color
color_number	color	1	Number literal color
color_match	color	4	Search match highlight color
color_selection	color	240	Selection highlight color
color_copied	color	22	Copy flash highlight color

Boolean values accept true or false.

Cursor type accepts:

• 0 — block cursor
• 1 — underline cursor
• 2 — beam (vertical bar) cursor

Color values accept three formats:

• #RRGGBB — 24-bit true color (e.g. #f92672). Works on all modern terminals.
• 0–255 — 256-color ANSI index.
• -1 — terminal default (for color_bg only).

Built-in themes use true color by default. The default theme uses basic ANSI colors for maximum compatibility.

Built-in themes

Theme	Background
default	Terminal default (ANSI colors, max compatibility)
monokai	#272822
dracula	#282a36
nord	#2e3440
gruvbox	#282828
solarized-dark	#002b36
one-dark	#282c34
retrobox	#1d2021

All themes except default use 24-bit true color.

Set a theme in ~/.ekorc:

theme = dracula

Individual color_* keys override the theme's values when both are present.

Custom themes

Create theme files in ~/.eko/themes/ with the .theme extension. They use the same key = value format with only color keys:

# ~/.eko/themes/my-theme.theme
color_bg       = #1a1b26
color_comment  = #565f89
color_keyword1 = #bb9af7
color_keyword2 = #7aa2f7
color_string   = #9ece6a
color_number   = #ff9e64
color_match    = #e0af68

Then activate it:

# ~/.ekorc
theme = my-theme

Custom themes in ~/.eko/themes/ take priority over built-in themes of the same name.

License

This project is based on kilo by Salvatore Sanfilippo, released under the BSD 2-Clause license.