OSC 133 — Semantic prompt marks (FinalTerm A / B / C / D)

Tag shell prompt-start / command-start / output-start / command-end so the terminal can jump between prompts, fold output, and decorate exit codes.

Byte forms

Every common string-literal form so you can paste-and-search either direction.

\\x1b[

\x1b]133;A\x07   (prompt start)   \x1b]133;B\x07   (command start)   \x1b]133;C\x07   (output start)   \x1b]133;D;<exit>\x07   (command end)

\\033[\033]133;A\007 / \033]133;B\007 / \033]133;C\007 / \033]133;D;0\007

\\e[\e]133;A\a / \e]133;B\a / \e]133;C\a / \e]133;D;0\a

ESC [ESC ] 133 ; A BEL etc.

hex1b 5d 31 33 33 3b 41 07 / ...3b 42 07 / ...3b 43 07 / ...3b 44 ... 07

Description

FinalTerm-defined **shell integration** protocol now widely adopted by Kitty, WezTerm, Ghostty, iTerm2, Warp, VS Code's terminal, and (partially) Windows Terminal. Four mark codes carve a shell session into structured blocks: - **`OSC 133 ; A ST`** — prompt start (emitted just before `PS1` renders). - **`OSC 133 ; B ST`** — command start (between prompt and the user's input). - **`OSC 133 ; C ST`** — output start (after pressing Enter; before the command's stdout/stderr begins). - **`OSC 133 ; D [ ; <exit-code> ] ST`** — command end (after the command exits; optional numeric exit code). The terminal turns these into UX: **jump to previous / next prompt** (kitty `kitten select-prompt`, iTerm2 ⌘↑/⌘↓, WezTerm `ActivateCommandPalette`), **fold a single command's output** (iTerm2, WezTerm), **decorate the prompt gutter** with the exit code (red triangle / green tick — kitty, iTerm2, Ghostty), and **scroll one command at a time** instead of one screen at a time. Most modern shell-integration plugins (`atuin`, `starship`'s wrappers, the bash/zsh hooks shipped with kitty / wezterm / iTerm2) wire these automatically — `__prompt_command` emits A, the `PS1` ends with B, the `DEBUG`/`preexec` hook emits C, and `precmd` emits D with `$?`. Sub-parameters used in practice: `aid=<unique>` (used by Warp / kitty to disambiguate concurrent shells), `cl=m` on `A` (the 'multi-line prompt' hint), `k=i`/`k=r` on `B` (input vs. continuation). The protocol is opt-in — emitting these into a terminal that doesn't recognise them just dropps the bytes; emit them unconditionally.

Spec citation: FinalTerm Semantic Prompts / xterm-ctlseqs (OSC 133)

Parameters

A / B / C / D	Mark type: A prompt-start, B command-start, C output-start, D command-end. Each carves a structural boundary the terminal can navigate to.
exit-code	Optional integer after `D;` — the just-finished command's `$?`. Used to decorate the prompt gutter with success / failure indicators.

Examples

bash

# zsh/bash shell-integration sketch (real impls handle PS1 specially):\nPS1='\[\e]133;A\a\]\u@\h \W $ \[\e]133;B\a\]'\npreexec() { printf '\033]133;C\007'; }\nprecmd()  { printf '\033]133;D;%d\007' "$?"; }

python

# Manually frame a command exec inside a Python REPL:\nimport sys, subprocess\nsys.stdout.write('\x1b]133;C\x07')                  # output starts\nrc = subprocess.run(['ls']).returncode\nsys.stdout.write(f'\x1b]133;D;{rc}\x07')             # command ends with exit code

fmt.Print("\x1b]133;A\x07")          // before prompt\nfmt.Print("$ \x1b]133;B\x07")        // command waiting\n// … run command, capture rc …\nfmt.Printf("\x1b]133;D;%d\x07", rc)

javascript

// Node REPL wrapping a child:\nprocess.stdout.write('\x1b]133;C\x07')\nconst child = spawn('npm', ['test'])\nchild.on('close', code => process.stdout.write(`\x1b]133;D;${code}\x07`))

printf("\x1b]133;A\x07");   /* prompt-start */\nprintf("%s$ ", cwd);\nprintf("\x1b]133;B\x07");   /* command-start */\n/* … fork+exec, wait … */\nprintf("\x1b]133;D;%d\x07", WEXITSTATUS(status));

Terminal support

xterm: no
Linux console (fbcon): no
macOS Terminal.app: no
iTerm2: yes
Windows Terminal: partial
cmd.exe / ConPTY: no
kitty: yes
alacritty: no
WezTerm: yes
Ghostty: yes
GNOME Terminal: partial
Konsole: partial
tmux: no
GNU screen: no

xterm	Linux console (fbcon)	macOS Terminal.app	iTerm2	Windows Terminal	cmd.exe / ConPTY	kitty	alacritty	WezTerm	Ghostty	GNOME Terminal	Konsole	tmux	GNU screen
no	no	no	yes	partial	no	yes	no	yes	yes	partial	partial	no	no

Related sequences

In the family cookbook

OSC cookbook · 5. Shell prompt marks — `OSC 133` (FinalTerm A / B / C / D)