How do I make \a (BEL) flash the screen instead of beeping audibly?

It's a terminal preference, not a sequence change — \x07 (BEL) is dispatched by the emulator, which then decides whether to ring the system bell or flash the window. xterm has bellIsUrgent + visualBell X resources, iTerm2 ships a per-profile *Visual bell* toggle, Windows Terminal exposes bellStyle: "visual" in settings.json, gnome-terminal / Konsole have a *Visual bell* checkbox in the profile dialog, and kitty / wezterm / alacritty all expose enable_audio_bell / audible-bell. Apps that need to *force* a flash regardless of terminal config can emit \x1b[?5h\x1b[?5l (DECSCNM on/off — the screen-reverse mode), which most emulators render as a single-frame visual flash.

Why does \r work as \r\n from my code but stays a bare carriage return in raw-mode?

POSIX terminals interpose an onlcr / opost translation in the tty line discipline — when output processing is on (the default for cooked mode), a lone \n is rewritten as \r\n before reaching the emulator. stty raw (or any TUI calling cfmakeraw()) clears OPOST, so your bytes hit the terminal verbatim: \n then becomes a pure line-feed (cursor down, column unchanged) and you must emit \r yourself to return to column 1. This is why progress-bar loops written for raw-mode TUIs explicitly use \r (or \x1b[1G, see cursor-column) instead of relying on \n. The reverse symptom — ladder-stepped output under stty -onlcr — is the same root cause.

C0 controls — BS, HT, LF, CR, BEL (single-byte codes)

The single-byte C0 control characters that move the cursor or signal events — no ESC introducer needed.

Byte forms

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

\\x1b[\x08 BS \x09 HT \x0a LF \x0d CR \x07 BEL

\\033[\010 / \011 / \012 / \015 / \007

\\e[\b / \t / \n / \r / \a

ESC [BS / HT / LF / CR / BEL

hex08 / 09 / 0a / 0d / 07

Description

These five single-byte controls predate ANSI/VT and are still acted on by every terminal: BS (0x08, \b) moves the cursor one cell left (does NOT erase — pair with a space + BS again to erase, or use EL). HT (0x09, \t) advances the cursor to the next tab stop (default every 8 columns). LF (0x0a, \n) moves down one line (and, with onlcr tty mode, returns to column 1 — Unix shells rely on this, which is why a raw \n looks ladder-stepped under stty -onlcr). CR (0x0d, \r) returns to column 1 of the current line — used for progress bars (\r + redraw). BEL (0x07, \a) rings the audible bell or flashes the visual bell depending on the terminal's setting; it also serves as the de-facto OSC string terminator (see OSC 0/2 and OSC 8). None of these consume an ESC byte — they are part of the C0 control set inherited from ASCII (1963) / ECMA-6.

Spec citation: ECMA-48 §8.2 (C0 set) / ASCII / ECMA-6

Parameters

BS (0x08)	backspace — cursor left 1
HT (0x09)	horizontal tab — to next tab stop
LF (0x0a)	line feed — down 1 line
CR (0x0d)	carriage return — to column 1
BEL (0x07)	bell — audible/visual alert; OSC terminator

Examples

bash

printf '\rprogress: 50%%\r'   # CR redraws current line\nprintf 'beep\a\n'           # BEL rings the bell

python

import sys, time\nfor i in range(101):\n  sys.stdout.write(f'\r{i}%'); sys.stdout.flush(); time.sleep(0.02)

fmt.Print("\rprogress: 50%\r")

javascript

process.stdout.write('\rprogress: 50%\r')

printf("\rprogress: 50%%\r");

Used in

Real-world tools that emit this sequence — anchors the bytes to commands you've already used.

npm, pnpm, pip, cargo progress barsevery progress tick emits `\r` to redraw the line in place — universal across language package managers
tput bel, printf '\a'shell scripts ring the system bell on errors or completion notifications
readline, GNU bash, zsh line editor`\b` (BS) backspaces in cooked-mode editing; cooked-mode `\n` translated to `\r\n` via `onlcr`
column, expand, cat -T`\t` (HT) is the table-cell separator everything in coreutils parses against
asciinema, script — record the raw byte stream including all C0 controls

Frequently asked

Short answers to the questions developers actually search for this sequence.

How do I make \a (BEL) flash the screen instead of beeping audibly?: It's a terminal preference, not a sequence change — \x07 (BEL) is dispatched by the emulator, which then decides whether to ring the system bell or flash the window. xterm has bellIsUrgent + visualBell X resources, iTerm2 ships a per-profile *Visual bell* toggle, Windows Terminal exposes bellStyle: "visual" in settings.json, gnome-terminal / Konsole have a *Visual bell* checkbox in the profile dialog, and kitty / wezterm / alacritty all expose enable_audio_bell / audible-bell. Apps that need to *force* a flash regardless of terminal config can emit \x1b[?5h\x1b[?5l (DECSCNM on/off — the screen-reverse mode), which most emulators render as a single-frame visual flash.
Why does \r work as \r\n from my code but stays a bare carriage return in raw-mode?: POSIX terminals interpose an onlcr / opost translation in the tty line discipline — when output processing is on (the default for cooked mode), a lone \n is rewritten as \r\n before reaching the emulator. stty raw (or any TUI calling cfmakeraw()) clears OPOST, so your bytes hit the terminal verbatim: \n then becomes a pure line-feed (cursor down, column unchanged) and you must emit \r yourself to return to column 1. This is why progress-bar loops written for raw-mode TUIs explicitly use \r (or \x1b[1G, see cursor-column) instead of relying on \n. The reverse symptom — ladder-stepped output under stty -onlcr — is the same root cause.

Terminal support

xterm: yes
Linux console (fbcon): yes
macOS Terminal.app: yes
iTerm2: yes
Windows Terminal: yes
cmd.exe / ConPTY: yes
kitty: yes
alacritty: yes
WezTerm: yes
Ghostty: yes
GNOME Terminal: yes
Konsole: yes
tmux: yes
GNU screen: yes

xterm	Linux console (fbcon)	macOS Terminal.app	iTerm2	Windows Terminal	cmd.exe / ConPTY	kitty	alacritty	WezTerm	Ghostty	GNOME Terminal	Konsole	tmux	GNU screen
yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes

Related sequences

In the family cookbook

C0 cookbook · 1. CR + LF — the line-ending pair