nicholascarroll/emil

Minimalist, Emacs-style text editor for the terminal - nicholascarroll/emil

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README

emil

emil is a small, portable text editor for UTF-8 files, providing a core subset of emacs commands in the terminal. Written in C99, emil is single-threaded and runs on any system providing POSIX.1-2001 and a VT100-compatible terminal. It eschews common sources of complexity: scripting, plugins, configuration files, background network activity, and auto-save files. Capabilities

Edit any left-to-right Unicode script Visual text selection Edit rectangular text regions Kill ring ("clipboard history") Snippets (as session-local registers) Regular expression search (POSIX ERE) Keystroke macros Shell integration Word wrap Split windows Mark ring Bookmarks (as session-local registers) Jump to symbol definition (ctags)

Installation Unix / Linux / macOS make && sudo make install Android (Termux)

Excludes shell integration.

make android Git for Windows / MSYS2

Run in an MSYS2 terminal (not mingw64, which lacks termios). Install compilers and libraries:

pacman -S msys2-devel msys2-runtime-devel

Build and install:

make && make install Getting Started Open a file: emil file.txt Essential Commands

Action Command

Open file Ctrl-x Ctrl-f

Save file Ctrl-x Ctrl-s

Quit emil Ctrl-x Ctrl-c

Mark (to select text) Ctrl-Space

Cut Ctrl-w

Copy Alt-w or Ctrl-c

Paste Ctrl-y

Undo Ctrl-_

Search Ctrl-s

Cancel Ctrl-g

For the complete command reference, see the man page: man emil Shell-Oriented Editing emil is designed to be used with the shell set to emacs-mode 1. In Bash the mode is set in the user's ~/.bashrc: set -o emacs Entries in ~/.inputrc are usually also needed for the copy and kill keybindings:

retain system-wide defaults

"\C-w": kill-region "\ew": copy-region-as-kill Shell Integration Shell integration is enabled by default and is disabled at build time with -DEMIL_DISABLE_SHELL. It allows shell commands to be run on the buffer:

Alt-| Takes the current region, feeds it to the shell command entered in the minibuffer, and displays the output in a Shell Output buffer.

Ctrl-u Alt-| Takes the current region, feeds it to the shell command, and replaces the region with the output of the command.

Alt-! Takes a shell command in the minibuffer and displays the output in Shell Output.

Alt-x diff-buffer-with-file Shows unsaved changes.

Example uses of Shell Integration

Task Command Keys To Use

Fill region fmt Ctrl-u Alt-|

Sort lines sort Ctrl-u Alt-|

Align columns column -t Ctrl-u Alt-|

Align text table column -t -s '|' -o '|' Ctrl-u Alt-|

Number lines cat -n Ctrl-u Alt-|

Word count wc Alt-|

Solve math bc Alt-| or Ctrl-u Alt-|

Format JSON jq . Alt-| or Ctrl-u Alt-|

Find typos aspell list Alt-|

Format C code clang-format Ctrl-u Alt-|

Lint shell script shellcheck - Alt-|

Trim whitespace sed 's/[[:space:]]*$//' Ctrl-u Alt-|

De-duplicate lines awk '!seen[$0]++' Ctrl-u Alt-|

Shell Drawer Ctrl-x Ctrl-z suspends emil while preserving the current editor screen. This permits shell commands to be executed in the terminal below the editor content, after which editing may be resumed with fg. Notes:

less clears the terminal when it quits; less -X and more do not. The named command cd (change directory) in emil does not also change the directory in the shell.

System Clipboard Integration Ctrl-c copies selected text to both the kill ring and the user's system clipboard when an OSC 52-enabled terminal client is used. Selections larger than 74,993 bytes are not sent to the clipboard and a status message is displayed. Some terminal emulators have lower limits and will silently fail after writing only the first part of the text to the system clipboard. Editing Large Files emil is not designed for editing very large files. Files larger than 1 GiB cannot be opened. Internals Each buffer is an array of logical lines (erow) holding raw UTF-8 bytes. Every buffer contains only valid UTF-8; files that fail validation are rejected at load time. Rendering and text layout never modify the buffer. Display widths are cached per row and recomputed only when a row is edited. A cumulative screen-line cache maps logical rows to screen positions. On each frame, the renderer reads raw bytes from the buffer and emits terminal-ready sequences directly into an append buffer. No intermediate render buffers exist. The append buffer is then written to the terminal and truncated. All input is processed in a single loop:

Read keystroke Execute command (may modify buffer) Refresh screen: clamp window offsets, rebuild caches if stale, scroll, redraw, flush

Contributing Bug fixes, portability improvements, performance work, and general code quality PRs are welcome. Please do not propose any new features. Credits and License emil is a derivative of japanoise/emsys and is distributed under the MIT License.

Footnotes

Omitted from POSIX.1, see Rationale. ↩

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