OSC 9 — Desktop notification (iTerm2) and progress (ConEmu / Windows Terminal)

frame

OSC introducer: \x1b] ESC ] (0x1B 0x5D)

terminator (ST|BEL): ST \x1b\ · BEL \x07

parameters / subcommands

gotchas

• OSC 9 is OVERLOADED: 'OSC 9 ; text' = iTerm2 notification, 'OSC 9 ; 4 ; state ; pct' = ConEmu/Windows-Terminal progress. A receiver must inspect the first sub-parameter (literal '4') to tell them apart.
• Progress state 0 (with any percent) REMOVES the indicator; always clear it (OSC 9 ; 4 ; 0 ; 0) when your task ends or it lingers on the taskbar.
• iTerm2's plain OSC 9 notification has no title/options; for richer notifications use OSC 99 (kitty) or OSC 777 (urxvt) which differ in syntax.
• Terminals that don't recognize the form ignore it silently — feature-detect, don't assume.
• Over tmux/ssh the sequence needs passthrough to reach the outer terminal.

provenance

• source: https://iterm2.com/documentation-escape-codes.html
• version: iTerm2 docs + ConEmu docs + Microsoft Windows Terminal docs, retrieved 2026-05-29
• retrieved: 2026-05-29 · updated: 2026-05-29T00:00:00Z

per-fact attribution:

• #notify — https://iterm2.com/documentation-escape-codes.html iTerm2: OSC 9 ; <message> ST posts a desktop notification (Growl-style).
• #progress — https://conemu.github.io/en/AnsiEscapeCodes.html ConEmu: OSC 9 ; 4 ; st ; pr ST sets the taskbar progress (st = state: 0 remove, 1 normal, 2 error, 3 indeterminate, 4 paused; pr = 0..100).
• #progress — https://learn.microsoft.com/en-us/windows/terminal/tutorials/progress-bar-sequences Windows Terminal adopted ConEmu's OSC 9 ; 4 ; state ; progress sequence to show progress in the taskbar/tab.

see also

• terminal-osc/99
• terminal-osc/777
• terminal-osc/133