kg —
a small text editor with Emacs keybindings
-R- Open all files given on the command line in read-only mode.
-V- Print version and exit.
-h- Print a short usage message and exit.
kg is a minimal terminal text editor with
Emacs-style keybindings. It supports syntax highlighting for many programming
languages, multiple buffers, split windows, incremental search, a kill ring,
and undo/redo.
kg does not depend on curses; it uses VT100
escape sequences directly.
If no files are given,
kg opens a scratch
buffer. Multiple files each open in their own buffer.
| Key |
Action |
| C-f / → |
Move forward one character |
| C-b / ← |
Move backward one character |
| C-n / ↓ |
Move to next line |
| C-p / ↑ |
Move to previous line |
| C-a / Home |
Move to beginning of line |
| C-e / End |
Move to end of line |
| C-v / PgDn |
Scroll down one page |
| M-v / PgUp |
Scroll up one page |
| M-f / C-→ |
Move forward one word |
| M-b / C-← |
Move backward one word |
| M-e |
Move forward one sentence |
| M-a |
Move backward one sentence |
| C-↑ / M-{ |
Move to previous paragraph |
| C-↓ / M-} |
Move to next paragraph |
| C-Home / M-< |
Move to beginning of buffer |
| C-End / M-> |
Move to end of buffer |
| C-PgUp / C-PgDn |
Move to beginning / end of buffer |
| M-m |
Back to indentation on current line |
| M-r |
Cycle cursor through top/middle/bottom of window |
| M-g |
Go to line (prompts for line or line:col) |
| C-u |
Numeric prefix for the next command (see below) |
C-u captures a count that the next command
runs that many times. Type
C-u alone for 4,
repeat
C-u to multiply by 4 each time
(‘C-u C-u
⇒ 16, ‘C-u C-u C-u
⇒ 64’’), or follow
C-u with digits to set an explicit count
(‘C-u 8
⇒ 8, ‘C-u 1 0 0
⇒ 100’’).
C-g cancels an in-progress prefix. The
accumulated count is shown in the echo area while it is being built.
Cursor motion, character and word deletion, word-case commands, opening lines,
inserting newlines and inserting plain characters all honour the count;
‘C-u 80 -’ inserts eighty dashes, handy for header rules.
Commands without a meaningful repeat semantics ignore the count silently.
M-a and
M-e use a deliberately simple
sentence-boundary heuristic: a sentence ends at ‘.’,
‘?’, or ‘!’ immediately followed by whitespace.
Mid-text periods such as “Mr. Smith” or “e.g.”
will be mis-detected as sentence ends.
| Key |
Action |
| Enter |
Insert newline with auto-indent |
| Tab |
Insert tab (with bracket autocomplete) |
| Backspace |
Delete character before point |
| Delete |
Delete character at point |
| C-d |
Delete character at point |
| C-k |
Kill from point to end of line |
| C-o |
Open line (insert newline, keep cursor) |
| C-q |
Quoted-insert: insert the next byte literally |
| M-^ |
Join current line with the previous one |
| M-q |
Reflow paragraph to the fill column |
| C-x f |
Set the fill column (per-buffer) |
| M-u |
Upcase word forward from point |
| M-l |
Downcase word forward from point |
| M-c |
Capitalize word forward from point |
| M-; |
Toggle line comment |
| C-t |
Transpose the two characters around point |
| M-h |
Mark the paragraph around point |
| M-z |
Zap: kill up to and including a typed character |
| M-\ |
Delete all whitespace around point |
| M-SPC |
Collapse whitespace around point to one space |
C-k at end of line joins it with the next
line (Emacs behavior). Killed text is appended to the kill ring when
C-k commands are consecutive.
C-q reads the next byte from the terminal
verbatim and inserts it, bypassing auto-indent and bracket completion. Used to
embed a literal Tab, Escape, or other control byte — handy when editing
terminfo, sendmail.cf or similar files that need a specific byte the regular
key bindings would otherwise consume.
M-; toggles a line comment on the current
line using the comment prefix defined by the current syntax (e.g.
‘//’ for C, ‘#’ for Python and Shell). If the mark
is set, every line between the mark and the cursor is toggled. When adding a
comment the prefix is inserted at column 0 followed by a space; when removing
one, the prefix and the optional following space are deleted.
M-q reflows the paragraph around point to the
fill column, re-applying the indentation of the first line to every wrapped
line. Paragraph boundaries are blank lines, and the whole reflow is a single
undo step.
C-x f sets the fill column that
M-q wraps to. It prompts in the echo area,
seeded with the current value; empty input leaves the setting unchanged. The
fill column is per-buffer and defaults to 72.
M-q never wraps wider than the window, so a
larger value is clamped to the window width when reflowing.
| Key |
Action |
| C-Space |
Set mark at point |
| C-w |
Kill region (cut to kill ring) |
| M-w |
Copy region (copy to kill ring) |
| C-y |
Yank from kill ring (paste) |
Set the mark with
C-Space; the region between
point and mark renders in reverse video and tracks the cursor as it moves. Cut
it with
C-w, copy with
M-w, or paste from the kill ring anywhere
with
C-y. The highlight is per-buffer; it
survives a
C-x b switch and reappears when
you come back, and it follows Emacs' transient-mark convention: the region
deactivates on
C-g, on the first edit, and
after a region command (
C-w,
M-w) has consumed it. The mark itself stays
set for the next
C-x C-x. The kill ring is
shared across all buffers.
| Key |
Action |
| S-← / S-→ |
Extend region one character |
| S-↑ / S-↓ |
Extend region one line |
| S-Home / S-End |
Extend region to line bounds |
| S-PgUp / S-PgDn |
Extend region one page |
| C-S-← / C-S-→ |
Extend region one word |
| C-S-↑ / C-S-↓ |
Extend region one paragraph |
| C-S-Home / C-S-End |
Extend region to buffer beginning / end |
| Shift-Delete |
Cut region |
| Shift-Insert |
Paste from kill ring |
| Ctrl-Insert |
Copy region |
| Delete |
Delete active region (or character if none) |
Shift+motion drops the mark at point and extends the region as the cursor moves,
so anyone coming from a modern GUI editor no longer has to remember
C-Space first. The region is transient: a
non-shifted key tears it down after the command runs, while region-consuming
commands (
C-w,
M-w,
C-x
C-x) still see the mark intact during their dispatch. Mixing styles
works: an explicit
C-Space mark stays
sticky when extended with shift+motion.
The CUA clipboard trio maps to the same kill ring as
C-w / M-w / C-y. Note that some terminals
(Terminator, gnome-terminal, ...) intercept
Shift-Insert and
Ctrl-Insert for their own clipboard
handling; unbind them in the terminal preferences if you want
kg to see them.
The same applies to several of the modifier-arrow bindings: Terminator grabs
Ctrl+Shift and the arrow keys to resize its panes and Alt and the arrow keys
to move between them, kitty reserves Ctrl+Shift for its own shortcuts (tab
switching on left/right), and gnome-terminal takes Ctrl+PgUp/PgDn for tab
switching. Free the keys in the terminal preferences, or fall back on the
plain Emacs bindings, which cover the same ground:
C-Space with
M-b,
M-f,
M-{,
M-}, window motion with
C-x o, and
M-< / M-> for the buffer ends.
The rxvt family (rxvt, urxvt) is a harder case: by a legacy encoding it cannot
distinguish Ctrl+Shift with an arrow key from a plain Shift+arrow –
both send the same bytes – so those combinations cannot be told apart
there, whatever the configuration. (The keypad keys, such as Ctrl+Shift+Home,
do have distinct encodings and work.) Remapping the cursor keys to their xterm
sequences with a
~/.Xresources keysym
resource is the only cure. Note also that
urxvt(1) opens an
ISO 14755 Unicode-entry prompt on Ctrl+Shift by default, which shadows
these keys until it is turned off.
| Key |
Action |
| C-x Space |
Rectangle mark mode |
| C-x r k |
Kill rectangle (cut) |
| C-x r y |
Yank rectangle (paste at point) |
| C-x r d |
Delete rectangle (no save) |
| C-x r c |
Clear rectangle (spaces) |
C-x Space sets a rectangle mark at point and
turns the highlight rectangular: every row in the row range gets reverse-video
on the same visual column span, lined up across tabs and UTF-8 content. The
same transient-mark tear-down rules apply:
C-g, an edit, or a region command ends the
mode.
C-x r y pastes the last killed rectangle at
point, padding short target rows with spaces and appending new rows when the
buffer is too short.
C-x r c overwrites
every char in the rectangle with a space, padding short rows out to the right
edge so the rectangle “exists” everywhere it should. Each
rectangle command is one undo step;
C-_
restores the entire affected range, including any padding or row appends.
| Key |
Action |
| C-s |
Incremental search forward |
| C-r |
Incremental search backward |
| M-% |
Query replace |
While searching: type to extend the query;
C-s or
→ or
↓ finds the next match;
C-r or
← or
↑ finds the previous match;
Enter accepts the match;
Esc cancels and returns to the original
position;
Backspace removes the last
character from the query.
M-% prompts for a search string and a
replacement string, then steps through every match from the current position
to the end of the buffer. At each match:
y
or
Enter replaces the match and moves to
the next;
n skips the match;
! replaces the current match and all
remaining matches without prompting;
q,
Esc, or
C-g stops the search. Each replacement is
independently reversible with
C-_.
| Key |
Action |
| C-_ / C-/ |
Undo last change |
Undo history is per-buffer. Each buffer keeps up to 1000 operations. The buffer
is marked unmodified when undo returns to the last-saved state.
| Key |
Action |
| C-x C-s / F2 |
Save current buffer |
| C-x s |
Save all modified buffers |
| C-x C-x |
Exchange point and mark |
| C-x C-w |
Write buffer to a different file (save as) |
| C-x i |
Insert file contents at point |
| C-x C-f |
Open file in new buffer |
| C-x C-r |
Open file read-only in new buffer |
| C-x C-q |
Toggle read-only mode on current buffer |
| C-x b |
Switch to buffer (interactive) |
| C-x k |
Kill (close) current buffer |
| C-x C-b |
Open buffer list |
| C-x C-c / F10 |
Quit |
Quitting with
C-x C-c offers to save each
modified buffer in turn, then asks for confirmation only if any are left
unsaved, like GNU Emacs.
The filename prompts for
C-x C-f,
C-x C-r,
C-x
C-w and
C-x i open an ido-style
picker. Matching directory entries render as a pick list in the echo area,
with the currently selected entry shown in reverse video.
What you type narrows the list by substring, the way Emacs' ido-mode does it:
typing ‘buf’ matches both ‘bufmgr.c’ and
‘editor_buffer.c’. Prefix matches still rank above mid-name
ones, so a leading letter prioritises the obvious candidate. Files already
open in a buffer get pushed to the back of the list, matched by basename the
way Emacs does it, so the default selection lands on something not yet open.
Handy when walking a directory to open several files in turn.
Left/Right arrows cycle the selection;
Enter
on a directory descends into it;
Enter on a
file completes the typed path and submits.
Backspace at a trailing ‘/’
walks you up one level in a single keystroke.
Tab extends the typed text to the longest
common prefix of the prefix- matched group, or appends a ‘/’
when the sole match is a directory.
C-x b opens the same picker shape against the
active buffers (everything except the current one). What you type narrows the
list by basename; Left/Right cycles;
Enter
switches to the selected buffer.
| Key |
Action |
| C-x 2 |
Split window horizontally |
| C-x 3 |
Split window vertically |
| C-x o |
Switch to next window |
| M-← / M-→ / M-↑ / M-↓ |
Select window in that direction |
| M-S-← / → / ↑ / ↓ |
Resize window, divider travels with the arrow |
| C-x ^ |
Enlarge window |
| C-x } |
Enlarge window horizontally |
| C-x { |
Shrink window horizontally |
| C-x + |
Balance windows |
| C-x 0 |
Delete current window |
| C-x 1 |
Delete all other windows |
| Key |
Action |
| C-x (/ F3 |
Start recording a keyboard macro |
| C-x) / F4 |
Stop recording |
| C-x e / F4 |
Execute (replay) last macro |
While recording,
C-x) or
F4 stops the macro. When not recording,
F4 (or
C-x
e) replays it. Every keystroke during recording is captured, including
characters typed into prompts (search strings, goto-line numbers, etc.), so
the macro replays the full interaction faithfully. The macro buffer holds up
to 1024 keystrokes.
| Key |
Action |
| C-g |
Cancel current operation |
| C-l |
Recenter: cycle current line to center, top, then bottom of window |
| C-z |
Suspend to the shell (resume with fg) |
| C-h / F1 |
Open *help* buffer (q closes) |
| M-x |
Execute named command |
| M-! |
Run shell command, insert output at point |
| M-| |
Pipe region through shell command, replace it with the output |
M-! prompts for a shell command line, runs it
with ‘
/bin/sh -c’, and inserts the
command's standard output at the cursor position. The command's standard error
is discarded so it cannot disturb the editor.
M-| extracts the active region, prompts for a
shell command, runs it with the region piped to standard input, and replaces
the region with the command's standard output. The original region text is
left in the kill ring so
C-y recovers it if
the result was not what was wanted.
Both commands are intended for non-interactive filters such as
sort(1),
fmt(1),
column(1),
jq(1) or
sed(1); interactive
programs that require a terminal will not work.
C-h opens a special
*help* buffer with the full key-binding
table. It is a regular buffer. Scroll with the usual motion keys, then press
q to dismiss it (or
C-x k, or
C-x
b back to wherever you were).
M-x prompts for a command name and executes
it. The completion prompt is the same ido-style picker as
C-x C-f: substring matching, Left/Right to
cycle,
Tab to extend to the longest common
prefix. Available commands:
- auto-revert-mode
- Toggle automatic re-reading of the current buffer's file when it changes
on disk. A buffer is only auto-reverted while it is unmodified; a buffer
with unsaved edits is never silently overwritten.
- capitalize-word
- Capitalize the word forward from point (first letter upper, rest lower).
Equivalent to
M-c.
- delete-horizontal-space
- Delete all spaces and tabs around point. Equivalent to
M-\.
- delete-trailing-space
- Remove trailing whitespace from the current line only. Reversible with
C-_.
- downcase-word
- Convert the word forward from point to lower case. Equivalent to
M-l.
- global-auto-revert-mode
- Toggle automatic re-reading for every buffer at once. Equivalent to
enabling
auto-revert-mode in every
buffer.
- goto-line
- Go to a specific line (prompts for line or line:col). Equivalent to
M-g.
- join-line
- Join the current line with the previous one, stripping leading whitespace
from the current line and inserting a space at the join point. Equivalent
to
M-^.
- just-one-space
- Collapse the spaces and tabs around point to a single space. Equivalent to
M-SPC.
- make-backup-files
- Toggle whether the first save of a visit keeps the previous version of the
file as a file~ backup. On by
default.
- mark-paragraph
- Set the mark at the paragraph's start and put point at its end. Equivalent
to
M-h.
- not-modified
- Clear the modified flag without saving.
- read-only-mode
- Toggle read-only mode on the current buffer, like
C-x C-q. While a buffer is read-only,
editing keys and buffer-modifying M-x
commands are refused. The mode line shows read-only as ‘%%’,
or ‘%*’ when the buffer has unsaved changes. A file the user
lacks permission to write opens read-only automatically.
- require-final-newline
- Toggle whether saving ensures the file ends with a newline. When on, a
buffer whose last line has text gains a trailing empty line (visible, as
in GNU Emacs) so the saved file ends with a newline. Off by default, so a
file without a final newline is preserved as-is.
- revert-buffer
- Re-read the current file from disk, discarding all unsaved changes. If the
buffer is modified a confirmation prompt is shown.
- save-buffer
- Save the current buffer to its file. Equivalent to
C-x C-s.
- set-fill-column
- Set the current buffer's fill column, the width
M-q reflows to. Equivalent to
C-x f.
- shell-command
- Run a shell command and insert its standard output at point. Equivalent to
M-!.
- shell-command-on-region
- Pipe the region through a shell command and replace it with the command's
standard output. Equivalent to
M-|.
- sort-lines
- Sort the lines the region spans into byte order (case-sensitive, not
numeric), as a single undo step. Needs an active mark.
- toggle-read-only
- Toggle read-only mode on the current buffer. Equivalent to
C-x C-q.
- transpose-chars
- Transpose the two characters around point. Equivalent to
C-t.
- upcase-word
- Convert the word forward from point to upper case. Equivalent to
M-u.
- version
- Print the editor version string in the status bar.
- what-cursor-position
- Show current line, column, and percentage through the buffer.
- whitespace-cleanup
- Remove trailing whitespace from every line in the buffer. Each modified
line is independently reversible with
C-_.
- zap-to-char
- Kill from point up to and including the next occurrence of a prompted
character. Equivalent to
M-z.
kg supports up to 20 open buffers. Each
buffer has its own undo history, dirty flag, and read-only state. Special
system buffers (the buffer list with
C-x
C-b, the help buffer with
C-h) have
names enclosed in ‘*’ and can be closed with
q when another buffer is available to
switch to.
The kill ring is global and shared across all buffers, so text killed in one
buffer can be yanked in another.
kg keeps track of each open file's
modification time and size as last seen. A background poll catches files that
have been rewritten by another process and tags the affected buffer with a
‘(changed)’ marker in the mode line. On
C-x C-s against such a buffer the user is
prompted to confirm before overwriting.
With
auto-revert-mode (or its global
counterpart
global-auto-revert-mode) turned
on, a clean buffer whose file has changed on disk is silently reloaded so the
view always matches the file. Modified buffers are never reverted
automatically — the ‘(changed)’ marker stays visible
until either the user saves (and is prompted) or explicitly runs
M-x revert-buffer to discard local edits.
The terminal can be divided into multiple windows with
C-x 2 (the current window splits into an
upper and a lower half) or
C-x 3 (into a
left and a right half), like in GNU Emacs: other windows are not disturbed, so
stacked and side-by-side layouts mix freely.
C-x
0 closes the current window and gives its space to the neighbors. Each
window shows one buffer and maintains its own scroll position and cursor.
Multiple windows may show the same buffer. Use
C-x
o to cycle between windows, or Meta and an arrow key to select the
window in that direction, like windmove in GNU Emacs. Up to 8 windows may be
open simultaneously.
Resize windows with Meta, Shift and an arrow key: the divider on that side of
the window travels with the arrow.
C-x ^
enlarges the current window,
C-x } and
C-x { widen and narrow it, and
C-x + evens out all window sizes again.
Syntax highlighting is detected automatically from the file extension or type,
e.g., Makefile. Hash-bang lines (#!) are used as a fallback when the extension
is not recognised.
| Language |
Extensions |
| C/C++ |
.c .h .cpp .hpp .cc |
| Python |
.py .pyw .pyi .pyx |
| Shell |
.sh .bash .zsh .profile .bashrc .zshrc |
| JavaScript |
.js .mjs .cjs |
| TypeScript |
.ts .tsx .d.ts |
| Rust |
.rs .rlib |
| Java |
.java |
| C# |
.cs .csx |
| PHP |
.php .phtml |
| Ruby |
.rb .rbw .rake |
| Swift |
.swift |
| SQL |
.sql .ddl .dml |
| Dart |
.dart |
| HTML |
.html .htm .xhtml |
| JSX |
.jsx |
| Vue |
.vue |
| Angular |
.component.ts .service.ts .module.ts .directive.ts .pipe.ts |
| Svelte |
.svelte |
| Makefile |
Makefile .mk .mak |
| Markdown |
.md .markdown .mkd |
kg automatically inserts matching closing
brackets when an opening bracket is typed, provided the cursor is at the end
of a line. Recognised pairs are ‘()’, ‘[]’, and
‘{}’. Autocomplete is suppressed when text arrives quickly, such
as during a paste operation.
M-g prompts for a line number, optionally
followed by a colon and a column number (e.g.
42:10). The cursor is moved to that position
and the view is centred vertically.
kg uses the controlling terminal
/dev/tty for raw-mode input and output.
Terminal size changes (SIGWINCH) are handled gracefully.
- /dev/tty
- Terminal device used for raw-mode I/O.
- file~
- Backup of a file's previous contents, written on the first save of each
visit unless disabled with
M-x
make-backup-files.
mg(1),
emacs(1),
vi(1)
kg is derived from
kilo by
Salvatore Sanfilippo. The name is a nod to
mg(1) (Micro GNU Emacs),
suggesting a kilo-gram-weight minimal editor with Emacs keybindings.
The
kg editor was created by
Joachim Wiberg (troglobit) based on the
original
kilo by
Salvatore Sanfilippo (antirez).