How the Test Script Works

This page explains what happens when you run curl -sL terminfo.dev/test | sh. The script is ~180 lines of POSIX shell — you can read every line below.

What it does, in plain language

Detects your terminal by reading environment variables ($TERM_PROGRAM, $GHOSTTY_RESOURCES_DIR, etc.)
Saves your terminal state so it can restore everything when done — even if interrupted
Switches to the alternate screen so your scrollback isn't affected
Runs 34 feature checks — each one sends an escape sequence and reads the response
Restores your terminal to exactly how it was before
Prints JSON results to stdout

It does NOT write files, install software, or make network requests.

How a feature check works

Every check follows the same pattern — send a query, read the response:

# Example: check if your terminal supports truecolor
# Send: ESC[38;2;255;0;128m  (set text color to RGB pink)
# Then: ESC[6n  (ask "where is the cursor?")
# If the terminal responds with cursor position, it understood the color sequence
printf '\033[38;2;255;0;128m\033[6n' > /dev/tty
response=$(dd bs=64 count=1 < /dev/tty)

The script uses a technique called DA1 sentinel — it sends the feature query AND a Device Attributes request (ESC[c) together. If only the DA1 response comes back, the feature isn't supported. This avoids waiting for timeouts on unsupported features.

The full script

Click to expand (~180 lines of shell)

#!/bin/sh
# terminfo.dev probe — test your terminal's feature support
# Usage: curl -sL terminfo.dev/probe | sh
#
# Sends escape sequences to the terminal, reads responses, outputs JSON.
# Progress to stderr, JSON to stdout. Requires a real terminal (/dev/tty).

if ! (stty -g </dev/tty >/dev/null) 2>/dev/null; then
  echo "Error: no terminal. Run in an interactive terminal." >&2
  echo "Usage: curl -sL terminfo.dev/probe | sh" >&2
  exit 1
fi

# Detect terminal from env vars
if [ -n "$GHOSTTY_RESOURCES_DIR" ]; then TN="ghostty"
elif [ -n "$KITTY_WINDOW_ID" ] || [ -n "$KITTY_PID" ]; then TN="kitty"
elif [ -n "$WEZTERM_EXECUTABLE" ]; then TN="wezterm"
elif [ "$TERM_PROGRAM" = "iTerm.app" ]; then TN="iterm2"
elif [ "$TERM_PROGRAM" = "Apple_Terminal" ]; then TN="terminal-app"
elif [ "$TERM_PROGRAM" = "vscode" ]; then TN="vscode"
elif [ "$TERM_PROGRAM" = "WarpTerminal" ]; then TN="warp"
elif [ "$TERM_PROGRAM" = "Alacritty" ]; then TN="alacritty"
elif [ -n "$GNOME_TERMINAL_SCREEN" ]; then TN="gnome-terminal"
elif [ -n "$KONSOLE_VERSION" ]; then TN="konsole"
elif [ -n "$WT_SESSION" ]; then TN="windows-terminal"
elif [ -n "$TERM_PROGRAM" ]; then TN=$(printf '%s' "$TERM_PROGRAM" | tr '[:upper:]' '[:lower:]')
else TN="unknown"
fi
TV="${TERM_PROGRAM_VERSION:-unknown}"
case "$(uname -s)" in Darwin) PL="macos";; Linux) PL="linux";; MINGW*|MSYS*|CYGWIN*) PL="windows";;
  *) PL="$(uname -s | tr '[:upper:]' '[:lower:]')";; esac

# Save/restore terminal state
ORIG_STTY=$(stty -g </dev/tty 2>/dev/null) || ORIG_STTY=""
cleanup() {
  [ -n "$ORIG_STTY" ] && stty "$ORIG_STTY" </dev/tty 2>/dev/null || stty sane </dev/tty 2>/dev/null || true
  printf '\033[?1049l\033[?25h\033[0m' >/dev/tty 2>/dev/null || true
}
trap cleanup EXIT INT TERM
raw() { stty raw -echo min 0 time "${1:-3}" </dev/tty 2>/dev/null || true; }

# I/O: write to tty, read from tty (result in R), drain pending input
wr() { printf '%s' "$@" >/dev/tty; }
rd() { R=$(dd bs="${1:-256}" count=1 </dev/tty 2>/dev/null) || R=""; }
drain() { raw 1; dd bs=256 count=1 </dev/tty >/dev/null 2>&1 || true; raw 3; }

# Query with DA1 sentinel: send $1+DA1, read until DA1 or timeout.
# Sets QR=response, QS=1 if pre-DA1 data found (feature supported)
qsentinel() {
  QR=""; QS=0; drain
  wr "$1" "$(printf '\033[c')"
  raw 3; _b=""; _n=10
  while [ "$_n" -gt 0 ]; do
    rd 256; [ -z "$R" ] && break; _b="${_b}${R}"
    case "$_b" in *'[?'*c*) break;; esac; _n=$((_n - 1))
  done
  QR="$_b"; [ -z "$_b" ] && return
  _ec=$(printf '%s' "$_b" | tr -cd '\033' | wc -c | tr -d ' ')
  if [ "$_ec" -gt 1 ]; then QS=1
  elif [ "$_ec" -eq 1 ]; then case "$_b" in *'[?'*c) QS=0;; *) QS=1;; esac; fi
}

# Simple query: send $1, read response (for DA1/DSR that need no sentinel)
qsimple() {
  QR=""; QS=0; drain; wr "$1"; raw 5; rd 256
  [ -n "$R" ] && { _b="$R"; raw 1; rd 256; QR="${_b}${R}"; QS=1; } || { QR=""; QS=0; }
}

# Cursor position report: ESC[6n → ESC[row;colR. Sets CR=row, CC=col
qcpr() {
  CR=0; CC=0; drain; wr "$(printf '\033[6n')"; raw 5
  _b=""; _n=5
  while [ "$_n" -gt 0 ]; do
    rd 32; [ -z "$R" ] && break; _b="${_b}${R}"
    case "$_b" in *R) break;; esac; _n=$((_n - 1))
  done
  _p=$(printf '%s' "$_b" | sed 's/.*\[//;s/R.*//')
  case "$_p" in *";"*) CR=$(printf '%s' "$_p" | cut -d';' -f1); CC=$(printf '%s' "$_p" | cut -d';' -f2);; esac
}

# DECRPM mode query: ESC[?N$p → ESC[?N;S$y. Sets MR=set/reset/unknown/""
qmode() {
  MR=""; qsentinel "$(printf '\033[?%d$p' "$1")"
  case "$QR" in *'$y'*) _s=$(printf '%s' "$QR" | sed 's/.*;//;s/\$.*//')
    case "$_s" in 1) MR="set";; 2) MR="reset";; 0) MR="unknown";; esac;; esac
}

# JSON accumulator
J=""; JN=0; JP=0
emit() {
  [ "$JN" -gt 0 ] && J="${J},"; J="${J}
    \"${1}\": ${2}"
  JN=$((JN + 1)); [ "$2" = "true" ] && JP=$((JP + 1))
}

# ── Run probes ────────────────────────────────────────────────────────
printf 'terminfo.dev probe — testing %s %s on %s\n' "$TN" "$TV" "$PL" >&2
raw 3; wr "$(printf '\033[?1049h\033[H\033[2J')"

printf '  device...\n' >&2
qsimple "$(printf '\033[c')";  case "$QR" in *'[?'*c*) emit "device.primary-da" "true";; *) emit "device.primary-da" "false";; esac
qsimple "$(printf '\033[5n')"; case "$QR" in *"0n"*) emit "device.status-report" "true";; *) emit "device.status-report" "false";; esac
qsentinel "$(printf '\033[>c')";          [ "$QS" = 1 ] && emit "device.secondary-da" "true" || emit "device.secondary-da" "false"
qsentinel "$(printf '\033[=c')";          [ "$QS" = 1 ] && emit "device.tertiary-da" "true"  || emit "device.tertiary-da" "false"
qsentinel "$(printf '\033P$q\"p\033\\')";  [ "$QS" = 1 ] && emit "device.decrqss" "true"      || emit "device.decrqss" "false"
qsentinel "$(printf '\033P+q544e\033\\')"; [ "$QS" = 1 ] && emit "device.xtgettcap" "true"    || emit "device.xtgettcap" "false"
qmode 7; [ -n "$MR" ] && [ "$MR" != "unknown" ] && emit "device.decrpm" "true" || emit "device.decrpm" "false"
qsentinel "$(printf '\033[>0q')";         [ "$QS" = 1 ] && emit "device.xtversion" "true"    || emit "device.xtversion" "false"

printf '  cursor...\n' >&2
qcpr; [ "$CR" -gt 0 ] 2>/dev/null && emit "cursor.position-report" "true" || emit "cursor.position-report" "false"
wr "$(printf '\033[3;5H')"; qcpr
[ "$CR" = "3" ] && [ "$CC" = "5" ] 2>/dev/null && emit "cursor.move.absolute" "true" || emit "cursor.move.absolute" "false"
wr "$(printf '\033[H')"; qcpr
[ "$CR" = "1" ] && [ "$CC" = "1" ] 2>/dev/null && emit "cursor.move.home" "true" || emit "cursor.move.home" "false"
wr "$(printf '\033[5;10H\0337\033[1;1H\0338')"; qcpr
[ "$CR" = "5" ] && [ "$CC" = "10" ] 2>/dev/null && emit "cursor.save-restore" "true" || emit "cursor.save-restore" "false"

printf '  sgr...\n' >&2
for _t in "1:sgr.bold" "3:sgr.italic" "4:sgr.underline.single" "9:sgr.strikethrough" "7:sgr.inverse"; do
  _c=$(printf '%s' "$_t" | cut -d: -f1); _id=$(printf '%s' "$_t" | cut -d: -f2)
  wr "$(printf '\033[1;1H\033[2K\033[%smX\033[0m' "$_c")"; qcpr
  [ "$CC" = "2" ] 2>/dev/null && emit "$_id" "true" || emit "$_id" "false"
done
case "$COLORTERM" in truecolor|24bit) emit "extensions.truecolor" "true";;
  *) wr "$(printf '\033[1;1H\033[2K\033[38;2;255;0;128mX\033[0m')"; qcpr
     [ "$CC" = "2" ] 2>/dev/null && emit "extensions.truecolor" "true" || emit "extensions.truecolor" "false";; esac

printf '  modes...\n' >&2
qmode 1049
if [ -n "$MR" ] && [ "$MR" != "unknown" ]; then emit "modes.alt-screen.enter" "true"; emit "modes.alt-screen.exit" "true"
else wr "$(printf '\033[?1049h\033[1;1HTEST')"; qcpr; wr "$(printf '\033[?1049l')"
  [ "$CR" -gt 0 ] 2>/dev/null && { emit "modes.alt-screen.enter" "true"; emit "modes.alt-screen.exit" "true"; } \
    || { emit "modes.alt-screen.enter" "false"; emit "modes.alt-screen.exit" "false"; }; fi
qmode 2004
if [ -n "$MR" ] && [ "$MR" != "unknown" ]; then emit "modes.bracketed-paste" "true"
else wr "$(printf '\033[?2004h')"; qcpr; wr "$(printf '\033[?2004l')"
  [ "$CR" -gt 0 ] 2>/dev/null && emit "modes.bracketed-paste" "true" || emit "modes.bracketed-paste" "false"; fi
for _t in "2026:modes.synchronized-output" "1004:modes.focus-tracking" "1000:modes.mouse-tracking" "1006:modes.mouse-sgr"; do
  _m=$(printf '%s' "$_t" | cut -d: -f1); _id=$(printf '%s' "$_t" | cut -d: -f2); qmode "$_m"
  [ -n "$MR" ] && [ "$MR" != "unknown" ] && emit "$_id" "true" || emit "$_id" "false"; done
qmode 2031
if [ -n "$MR" ] && [ "$MR" != "unknown" ]; then emit "modes.color-scheme-reporting" "true"
else qsentinel "$(printf '\033[?997n')"
  [ "$QS" = 1 ] && emit "modes.color-scheme-reporting" "true" || emit "modes.color-scheme-reporting" "false"; fi

printf '  extensions...\n' >&2
qsentinel "$(printf '\033[>1u\033[?u')"; wr "$(printf '\033[<u')"
[ "$QS" = 1 ] && emit "extensions.kitty-keyboard" "true" || emit "extensions.kitty-keyboard" "false"
qsentinel "$(printf '\033]10;?\007')"; [ "$QS" = 1 ] && emit "extensions.osc10-fg-color" "true" || emit "extensions.osc10-fg-color" "false"
qsentinel "$(printf '\033]11;?\007')"; [ "$QS" = 1 ] && emit "extensions.osc11-bg-color" "true" || emit "extensions.osc11-bg-color" "false"
_b64=$(printf 'terminfo-test' | base64 2>/dev/null || echo "dGVybWluZm8tdGVzdA==")
wr "$(printf '\033]52;c;%s\007' "$_b64")"; qcpr
[ "$CR" -gt 0 ] 2>/dev/null && emit "extensions.osc52-clipboard" "true" || emit "extensions.osc52-clipboard" "false"
wr "$(printf '\033]52;c;%s\007' "$_b64")"
qsentinel "$(printf '\033]52;c;?\007')"; [ "$QS" = 1 ] && emit "extensions.osc52-read" "true" || emit "extensions.osc52-read" "false"
qsentinel "$(printf '\033]1337;ReportCellSize\007')"
case "$QR" in *"ReportCellSize="*) emit "extensions.osc1337-cellsize" "true";; *) emit "extensions.osc1337-cellsize" "false";; esac
qsentinel "$(printf '\033]1337;RequestCapabilities\007')"
case "$QR" in *"Capabilities="*) emit "extensions.osc1337-capabilities" "true";; *) emit "extensions.osc1337-capabilities" "false";; esac
qsimple "$(printf '\033[c')"
case "$QR" in *";4;"*|*";4c"*) emit "extensions.sixel-da1" "true";; *) emit "extensions.sixel-da1" "false";; esac

wr "$(printf '\033[?1049l')"; cleanup

# Output
_gen=$(date -u +"%Y-%m-%dT%H:%M:%SZ" 2>/dev/null || echo "unknown")
_pct=0; [ "$JN" -gt 0 ] && _pct=$(( (JP * 100) / JN ))
printf '  done: %d/%d passed (%d%%)\n\n' "$JP" "$JN" "$_pct" >&2
cat <<EOF
{
  "terminal": "$TN",
  "terminalVersion": "$TV",
  "os": "$PL",
  "source": "curl-probe",
  "generated": "$_gen",
  "results": {$J
  }
}
EOF

Want to contribute?

Run the script and submit your results:

bash

npx terminfo.dev submit

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SGR (Text Styling)

Cursor

Text

Erase

Editing

Modes

Scrollback

Reset

Extensions

Character Sets

Device Status

Input Protocols

Unicode

Parser Backends

Multiplexers

How the Test Script Works

What it does, in plain language

How a feature check works

The full script

Want to contribute?

How the Test Script Works ​

What it does, in plain language ​

How a feature check works ​

The full script ​

Want to contribute? ​

How the Test Script Works

What it does, in plain language

How a feature check works

The full script

Want to contribute?