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Icon name (OSC 1)

Category: extensions · Baseline: core · Tags: Operating System Commands (OSC), Xterm Extensions · Specification ↗

ESC ] 1 ; Pt BEL
OSC 1 sets the icon name (without changing the window title). The sequence is ESC ] 1 ; Pt BEL where Pt is the icon name string. This is the companion to OSC 0 (which sets both icon name and title) and OSC 2 (which sets only the title). Originally used by X11 window managers to label minimized windows, icon name is less commonly used in modern terminals but remains part of the xterm protocol. Some terminals treat OSC 1 identically to OSC 0 or ignore the icon name entirely.
How this is testedautomated
Send \x1b]1;test-icon\x07 and verify the terminal remains responsive (icon name accepted without error).

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 9 tested terminals — universal adoption. Part of the Core TUI baseline.

Supported by 14 of 14 backends (100%)

Terminal Applications

TerminalVersionSupportNotes
iTerm23.6.9✓ yes
Ghostty1.3.1✓ yes
VS Code✓ yes
Warp✓ yes
Cursor✓ yes
Terminal.app✓ yes

Headless Backends

Parser correctness only — a means the parser accepts the sequence.

BackendVersionSupportNotes
Alacritty0.26.0✓ yes
Kitty0.40.0✓ yes
vt100.js0.2.1✓ yes
vterm0.2.0✓ yes
WezTerm0.1.0-fork.5✓ yes
xterm.js5.5.0✓ yes