OSC 9;4

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Experimental

OSC 9;4 reports task progress to the terminal, which can display it as a progress indicator in the taskbar, tab bar, or title bar. This enables build tools, package managers, and other long-running commands to provide visual progress feedback.

Syntax

OSC 9 ; 4 ; st ; pr ST
OSC 9 ; 4 ; st ; pr BEL

Formal syntax

OSC9_4 = 0x1b, "]", "9", ";", "4", ";", state, ";", progress, ( 0x07 | 0x1b, "\\" ) ;
state    = "0" | "1" | "2" | "3" | "4" ;
progress = digit, { digit } ;
digit    = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" ;

Parameters

Parameter	Description	Default
`st`	Progress state indicator	(required)
`pr`	Progress percentage (0-100)	(required)

The st (state) parameter controls the visual style of the progress indicator:

State	Meaning	Description
`0`	Hidden	Remove/hide the progress indicator
`1`	Default	Normal progress (typically green)
`2`	Error	Error state (typically red)
`3`	Indeterminate	Busy/spinner state with no specific percentage
`4`	Warning	Warning state (typically yellow)

Description

Per the Windows Terminal documentation, OSC 9;4 is a sub-command of the ConEmu OSC 9 protocol that allows applications to report progress to the terminal. The terminal can then display this progress in its taskbar button (on Windows), tab bar, or other UI elements.

This mechanism is particularly useful for:

Build systems reporting compilation progress
Package managers showing download/install progress
File operations like copying or compressing large files
CI/CD tools indicating pipeline stage progress

The progress indicator is typically shown in the operating system's taskbar. On Windows, this appears as a progress bar overlay on the terminal's taskbar icon. On other platforms, the rendering depends on the terminal emulator's implementation.

Setting the state to 0 (hidden) clears the progress indicator and returns the taskbar/tab to its normal appearance.

Examples

# Show 50% progress in default (green) state
printf '\e]9;4;1;50\a'

# Show completed progress
printf '\e]9;4;1;100\a'

# Show error state at 75%
printf '\e]9;4;2;75\a'

# Show indeterminate/busy state
printf '\e]9;4;3;0\a'

# Show warning at 30%
printf '\e]9;4;4;30\a'

# Clear the progress indicator
printf '\e]9;4;0;0\a'

# Simulate a progress bar for a loop
for i in $(seq 1 100); do
  printf '\e]9;4;1;%d\a' "$i"
  sleep 0.05
done
printf '\e]9;4;0;0\a'

Specifications

Specification	Section
Windows Terminal Progress Bar	—

Terminal support

Terminal	Support	Version	Notes
Terminal Emulators
Alacritty	✗	No	Not listed in escape_support.md OSC section
Bobcat	✓	0.9.6	WhenProgress callback added in commit 2d4399a
contour	✓	v0.6.2.8008	Progress reporting via OSC 9;4 (ConEmu format)
foot	✗	No	ConEmu/Windows Terminal progress explicitly ignored in osc.c:1389
Ghostty	✓	v1.0.0
iTerm2	✗	No	Not found in codebase
Kitty	✗	No	OSC 9;4 progress reporting explicitly discarded per changelog
Konsole	✓	Yes	ConEmu OSC 9;4 progress reporting in src/Vt102Emulation.cpp:1825-1851
mintty	✓	Yes	Implemented at termout.c:5149-5220, progress reporting (OSC 9;4)
mlterm	✗	No
PuTTY	✗	No	Not implemented in do_osc function
Rio	✗	No
rxvt-unicode	✗	No
st	✗	No
terminology	✗	No
VT100	✗	No
VTE	✓	Yes	OSC 9;4 progress reporting handled via conemu_extension
WezTerm	✓	Yes	OSC 9;4 ConEmuProgress for progress reporting - see wezterm-escape-parser/src/osc.rs:52,319-347,608-612
Windows Terminal	✓	Yes	DoConEmuAction subParam 4 calls SetTaskbarProgress for progress reporting
xterm	✗	No	No evidence in documentation or source code
xterm.js	✓	6.0.0	Requires addon-progress
Multiplexers
cy	✗	No
GNU Screen	✗	No
tmux	✗	No	Progress reporting not implemented
tuios	✗	No
Zellij	✗	No

Syntax​

Parameters​

Description​

Examples​

Specifications​

Terminal support​

See also​