{
  "id": "terminal-osc/10",
  "family": "terminal-osc",
  "slug": "10",
  "title": "OSC 10 — Set / query default foreground color",
  "summary": "OSC 10 ; spec ST sets the terminal's default foreground (text) color; OSC 10 ; ? ST queries it, and the terminal replies OSC 10 ; rgb:RRRR/GGGG/BBBB ST. This is the default text color, distinct from the indexed palette (OSC 4). Multiple OSC 10/11/12 settings can be chained because they consume successive parameters.",
  "kind": "control-sequence",
  "aliases": [
    "set foreground color",
    "query foreground",
    "OSC 10",
    "ESC ] 10",
    "default fg"
  ],
  "status": "de-facto",
  "verification": "verified",
  "tier": "B",
  "source_url": "https://invisible-island.net/xterm/ctlseqs/ctlseqs.html",
  "source_version": "xterm ctlseqs, patch #410, 2026/04/19",
  "retrieved_date": "2026-05-29",
  "attribution": [
    {
      "claim_ref": "#summary",
      "source_url": "https://invisible-island.net/xterm/ctlseqs/ctlseqs.html",
      "source_version": "xterm patch #410, 2026/04/19",
      "note": "xterm ctlseqs: Ps = 1 0 -> Change VT100 text foreground color to Pt. A '?' queries the color, reported back as a control sequence. Consecutive OSC 10/11/12... consume successive color parameters."
    }
  ],
  "see_also": [
    "terminal-osc/11",
    "terminal-osc/12",
    "terminal-osc/4"
  ],
  "ext_type": "terminal-escape@1",
  "ext": {
    "csi_or_osc": "OSC",
    "command_number": 10,
    "frame": {
      "introducer_7bit": "\u001b]",
      "introducer_7bit_readable": "ESC ] (0x1B 0x5D)",
      "introducer_8bit": "",
      "introducer_8bit_readable": "0x9D (single-byte OSC, 8-bit C1)",
      "note": "OSC frame per ECMA-48 5th ed. 1991 / ISO 6429. Command number 10 is an xterm/vendor convention with no formal registry."
    },
    "terminator": "ST|BEL",
    "terminator_detail": {
      "canonical_ST_7bit": "\u001b\\",
      "canonical_ST_7bit_readable": "ESC \\ (0x1B 0x5C)",
      "canonical_ST_8bit": "œ",
      "canonical_ST_8bit_readable": "0x9C (single-byte ST, 8-bit C1)",
      "alt_BEL": "\u0007",
      "alt_BEL_readable": "BEL (0x07)",
      "note": "ECMA-48 mandates ST; xterm and most modern terminals also accept BEL. Emit ST, accept both."
    },
    "params": [
      {
        "id": "set",
        "anchor": "#set",
        "name": "Set default foreground",
        "meaning": "OSC 10 ; spec ST sets the default text (foreground) color, where spec is an X11 color name or rgb:RR/GG/BB / #RRGGBB form.",
        "required": true,
        "byte_sequence_ST": "\u001b]10;#ffffff\u001b\\",
        "byte_sequence_ST_readable": "ESC ] 1 0 ; # f f f f f f ESC \\   ==  \\x1b]10;#ffffff\\x1b\\\\   (white foreground)",
        "byte_sequence_BEL": "\u001b]10;#ffffff\u0007",
        "byte_sequence_BEL_readable": "ESC ] 1 0 ; # f f f f f f BEL   ==  \\x1b]10;#ffffff\\x07",
        "subparams": []
      },
      {
        "id": "query",
        "anchor": "#query",
        "name": "Query default foreground",
        "meaning": "OSC 10 ; ? ST asks for the current default foreground; the terminal replies OSC 10 ; rgb:RRRR/GGGG/BBBB ST (16-bit-per-channel).",
        "required": false,
        "byte_sequence_ST": "\u001b]10;?\u001b\\",
        "byte_sequence_ST_readable": "ESC ] 1 0 ; ? ESC \\   ==  \\x1b]10;?\\x1b\\\\   (query; reply \\x1b]10;rgb:ffff/ffff/ffff\\x1b\\\\)",
        "byte_sequence_BEL": "\u001b]10;?\u0007",
        "byte_sequence_BEL_readable": "ESC ] 1 0 ; ? BEL   ==  \\x1b]10;?\\x07",
        "subparams": []
      }
    ],
    "gotchas": [
      "The query REPLY uses 16-bit-per-channel rgb:RRRR/GGGG/BBBB; do not assume it matches the width you wrote when setting.",
      "OSC 10/11/12 consume SUCCESSIVE parameters: 'OSC 10 ; fg ; bg ST' sets fg via 10 and bg via the implicit 11. To set only fg, send just one parameter.",
      "OSC 10 is the DEFAULT foreground (used where no SGR color is active); it is NOT a palette index — use OSC 4 for indexed colors and SGR 38 for per-run colors.",
      "Reading the query reply requires reading from the tty with a timeout, or the read blocks if the terminal doesn't answer.",
      "Reset to defaults with OSC 110 (reset foreground); restore on exit so the user's theme isn't left altered."
    ],
    "v1_smoke_test": {
      "asserts": "OSC 10 set and query forms render as byte-exact OSC strings in ST and BEL forms; query carries the literal '?'.",
      "behavioral_conformance": "deferred to v2."
    }
  },
  "updated": "2026-05-29T00:00:00Z"
}