led - Larry's Editor for Linux/Unix Terminal (1.0.7)

Dedicated to Neal Stephenson's vision of paper-like data safety.

Author: Larry Bruce Daniel. Assistance from Grok (xAI): grok-code-fast-1 on earlier versions, Grok 4.7 on 1.0.7.

What Works

• Data safety: unlimited undo/redo (10k cap), auto-save with versioned backups, crash recovery. Rejects files over max_file_size_mb (default 10MB) or with null bytes, and files whose line cache would pass memory_limit_mb. Cuts lines at max_line_length.
• Editing: insert, newline, backspace/delete, tabs (spaces or \t), word wrap (F3), selection, clipboard (Ctrl+A/C/X/V), regex search (Ctrl+/) and replace (Ctrl+R), syntax highlighting (C/C++ nesting, pre-parsed, per-line cache).
• Search chord: Ctrl+/ opens search. Byte 31 still works. foot and xterm modifyOtherKeys (ESC [27;5;47~) and kitty CSI-u (ESC [47;5u) are the same chord, so that sequence is not typed into the buffer.
• Display: F2 line numbers, F3 word wrap, F4 border toggle (see below), status bar (version/time/position/key-meter show_key_meter), Unicode/Cyrillic.
• Incremental rendering: cursor moves repaint only status line, single-line edits repaint only that row (75x less output); view_decide() + nesting cache.
• Border handling: text in derwin(stdscr, LINES-2,COLS-2,1,1) (border on) or derwin(stdscr, LINES-1,COLS,0,0) (border off); border only on FULL repaint. Paste-time border_filter_dup() strips | + - │ ─ ┌ ┐ └ ┘ ├ ┤ ┬ ┴ ┼ per line and drops pure ┌──┐ lines — replaces tr -d.
• Config: ~/.config/led/colorization.conf (colors, reserved_words, paired_keywords, syntax_extensions, show_key_meter, show_border), env LED_NO_BORDER=1 / LED_SHOW_BORDER.
• C/C++ editing: file:line:col and +N open on the diagnostic, Ctrl+G jumps there, Ctrl+] matches braces, word motions, Ctrl+K toggles //, Enter keeps indent, Shift+Tab outdents. Source files show line numbers.
• Tests: 229 tests (buffer, undo, clipboard, autosave, view, search wrap, search chord, indent, braces, save). ./led -t on your machine.
• **Open files in with .. in the path. It used to fail.

What Fails

• Large files: the whole file is still loaded into memory. There is no lazy load or mmap. led stops when the file exceeds max_file_size_mb, or when the next line would push the nesting cache past memory_limit_mb. The buffer stays empty and the status line says File too large or Too many lines. Raise those keys to accept the cost, or split the file first.
• Long lines: a line past max_line_length (default 10000) is cut on load. The status line says Long line truncated. Cut lines skip highlighting and use basic rendering.
• Limits: max_file_size_mb (1–100, default 10), memory_limit_mb (1–200, default 50), and max_line_length (80–100000, default 10000) are keys in colorization.conf. A value outside its range keeps the default.
• Language support: highlighting and parsing are built for C/C++; other languages may be incomplete. Turn highlighting off in config if a file fights you.
• Error handling: not fully standardized across modules.
• No per-buffer undo persistence across sessions.
• No fuzzing harness yet. Empty-file, size, null-byte, truncation, and memory-ceiling loads are tested.
• Input sanitization: no directory-traversal check beyond is_filename_safe.
• Terminal: xterm block-select still copies screen cells — use F4 off or filter; no OSC 52 system clipboard.
• Unknown languages like Python. Add the .py instead .c,.cpp.h in the colorization.conf file and the file will render.
• Work around, if the data gets corrupted, turning on line numbers with F2 will render correctly

Bugs: size and type (file, head sample), or a gdb ./led backtrace, at https://github.com/refgift/led/issues

Dependencies

C compiler, make (gmake on Unix), libncursesw, glibc regex.

Build / Install / Test

make              # builds ./led
make install      # installs to /usr/local/bin
make doc          # installs led.1
./led file.c
./led +142 file.c       # open at a line (compiler output)
./led file.c:142:8      # file:line or file:line:col
./led -t          # test mode (stderr, no curses) — also LED_TEST=1 ./led
man led           # after make doc

Keybindings

Keys	Action
Arrows, Home/End (×2 top/bottom), PgUp/PgDn	Navigation
Ctrl+Left / Ctrl+Right, or Esc then b / f	Previous / next word (_ counts as part of a word)
Ctrl+]	Jump to the matching () [] {} (skips strings and comments)
Ctrl+G	Go to line, or line:col
Printable, Enter, Backspace/Delete, Tab, Shift+Tab	Insert / delete / outdent
Enter at end of line	Copy indent; one extra level after { or (
Ctrl+K	Toggle a // comment on this line
Ctrl+W	Delete the previous word
Ctrl+Z / Ctrl+Y	Undo / Redo
Ctrl+S / Ctrl+Q	Save / Quit (Ctrl+Q again if the buffer is modified)
Ctrl+A / Ctrl+C / Ctrl+X / Ctrl+V	Select all / Copy / Cut / Paste (paste is border-filtered)
Ctrl+/ / Ctrl+R	Search / Replace (regex, wraps, 100-char limit). Ctrl+/ is byte 31 or the terminal's modified-key sequence
F2	Line numbers
F3	Word wrap
F4	Border on/off (subwindow inset vs full-width; pasted │ stripped)

Configuration

~/.config/led/colorization.conf — key=value, # comments, created on first run.

Colors (BLACK,RED,GREEN,YELLOW,BLUE,MAGENTA,CYAN,WHITE): normal_fg/bg, selection_fg/bg, semicolon_fg/bg, meta_level1..4_fg/bg, reserved_words_fg/bg.

Display/Border: show_border=0 (default off, 1 shows box). Toggled by F4.

Other: syntax_extensions=.c,.h,.C,.H,.cpp,.cc,.cxx,.hpp,.hh,.hxx, reserved_words=... (C and C++ keywords), paired_keywords=if-then,begin-end,(,), tab_width=8, spaces_for_tab=0, show_key_meter=1, show_line_numbers=0.

Limits: max_file_size_mb=10 (1–100), memory_limit_mb=50 (1–200), max_line_length=10000 (80–100000). A file over the size or memory ceiling is not opened. A longer line is cut and the status line says Long line truncated. A null byte is refused with Binary file.

Source files (those extensions) show line numbers unless show_line_numbers is set in the config. Ctrl+S replaces the file by rename and keeps its permission bits. Search wraps to the top and says so.

Example:

normal_fg=WHITE
normal_bg=BLACK
selection_fg=CYAN
selection_bg=BLACK
show_key_meter=1
show_border=0
syntax_extensions=.c,.h,.cpp