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Locale query/set (OSC 701)
ESC ] 701 ; locale BELOSC 701 queries or sets the terminal's current locale, which controls character encoding and text input behavior. To set:
ESC ] 701 ; locale BEL where locale is a locale identifier like en_US.UTF-8. To query: ESC ] 701 ; ? BEL, and the terminal responds with its current locale. Originally introduced by rxvt-unicode so applications running inside the terminal could discover or override the encoding the terminal was decoding text as — important for users who routinely mixed UTF-8 and legacy 8-bit encodings. Also supported by mintty. Modern terminals are universally UTF-8 and silently consume the sequence.How this is testedpartial
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OSC 701 ; ? BEL and verify the terminal responds with a locale string or silently consumes the query.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 4 tested terminals — universal adoption. Part of the Unicode 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 |