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OSC 9;4 progress bar
Category: extensions · Baseline: rich · Tags: Operating System Commands (OSC), ConEmu Extensions · Specification ↗
OSC 9;4 is a ConEmu-originated protocol for reporting task progress to the terminal. The sequence
ESC ] 9 ; 4 ; st ; pr BEL sets progress state (st: 0=remove, 1=normal, 2=error, 3=indeterminate, 4=paused) and percentage (pr: 0-100). Terminals render this as a native progress indicator — typically in the tab bar, title bar, or taskbar.
Originally a ConEmu extension, it has been widely adopted: Ghostty (1.2+), iTerm2 (3.6.6+), Windows Terminal, Konsole, mintty, and WezTerm all support it. This makes it one of the most cross-terminal ways to display progress. CLI tools like curl, wget, and build systems can emit these sequences to provide native progress feedback.How this is testedpartial
Send
Send
OSC 9;4;1;50 BEL (set 50% progress), verify the sequence is consumed (cursor doesn't advance). Clear with OSC 9;4;0 BEL.The same probe runs against headless backends (via Termless) and real terminal apps (via a daemon launched in each terminal). This lets us distinguish parser correctness from rendering correctness.
Analysis2026-04-06
Supported by all 7 tested terminals — universal adoption. Part of the Rich TUI baseline.
Supported by 8 of 14 backends (57%)
Terminal Applications
| Terminal | Version | Support | Notes |
|---|---|---|---|
| iTerm2 | 3.6.9 | ✓ yes | |
| Ghostty | 1.3.1 | ✓ yes | |
| VS Code | ✓ yes | ||
| Warp | ✓ yes | ||
| Cursor | ✓ yes | ||
| Terminal.app | ✓ yes |