term_query.sh

A small Bash script that probes terminal capabilities by sending standard VT/DEC/XTerm control sequences and parsing the replies.
It’s useful for debugging, comparing terminal emulators, or just learning what features your terminal supports.

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Features

The script currently queries and decodes:

• DECRQSS “ q” — Cursor shape (block / underline / bar, blinking or steady)
• DECRQM ?12 — Cursor blink mode
• CSI u — Keyboard enhancement / CSI u support flags
• DA1 (Primary Device Attributes) — Terminal “family” (VT100, VT220, VT320, etc.) and features
• DA2 (Secondary Device Attributes) — Terminal type, firmware version, cartridge number
• DA3 (Tertiary Device Attributes / DECRPTUI) — Terminal Unit ID (site + serial; xterm reports zeros)
• DECRQM ?2004 — Bracketed paste mode
• DECRQM ?1004 — Focus tracking
• DECRQM ?1006 — SGR mouse mode

The raw replies are shown with hexyl (if available) or hexdump -C, and then parsed into human-readable summaries.

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Usage

./term_query.sh [--passthrough]

Options:

• --passthrough
  If running inside tmux, wrap the queries using the passthrough mechanism (DCS Ptmux) so they reach the underlying terminal.

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Example Output

Preparing terminal...
Sending DIRECT queries to the current terminal...
→ DECRQSS cursor shape: Ps=2  [steady block]
→ DECRQM ?12 (blink): steady (off)  [state=2]
→ DA1 (primary): ?62;1;2;22c  [VT220 features: 132-columns, printer, ANSI-color]
→ DA2 (secondary): >0;3793;0 c  [type=VT100  version=3793  cartridge=0]
   note: this looks like an xterm-style reply (Pp=0, Pc=0; Pv is patch/version).
→ DA3 (tertiary / DECRPTUI): DCS ! | 0;0 ST
   note: looks like an xterm-style reply (zeros for site/serial).
→ CSI u: ON  [mode 1: disambiguate escape codes]
→ DECRQM ?2004: bracketed-paste: enabled
→ DECRQM ?1004: focus-events: disabled
→ DECRQM ?1006: mouse-sgr: enabled
Test finished.

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Requirements

• bash
• stty, dd (standard on Unix-like systems)
• hexyl (optional, for nicer hex dumps; falls back to hexdump -C)
• (Optional) tmux if using passthrough mode

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Reference

The control sequences are based on the XTerm Control Sequences documentation.
VT100/VT220 family attributes are decoded according to DEC and xterm conventions.

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License

MIT — see LICENSE.