{
  "id": "terminal-osc/52",
  "family": "terminal-osc",
  "slug": "52",
  "title": "OSC 52 — Clipboard set / query (base64)",
  "summary": "OSC 52 ; Pc ; Pd ST manipulates the system clipboard. Pc selects which clipboard ('c' = CLIPBOARD, 'p' = PRIMARY, etc.); Pd is the base64-encoded data to set, or '?' to query (the terminal replies with the clipboard contents, base64-encoded). Lets a program running anywhere — including over ssh — copy to the local clipboard.",
  "kind": "control-sequence",
  "aliases": [
    "clipboard",
    "set clipboard",
    "query clipboard",
    "OSC 52",
    "ESC ] 52",
    "copy over ssh"
  ],
  "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 = 5 2 -> Manipulate Selection Data. Pc is the clipboard(s) (c/p/q/s/0-7); Pd is base64 data, '?' to report. Default Pc selects CLIPBOARD and PRIMARY."
    }
  ],
  "see_also": [
    "terminal-osc/4"
  ],
  "ext_type": "terminal-escape@1",
  "ext": {
    "csi_or_osc": "OSC",
    "command_number": 52,
    "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 52 is an xterm 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 also accepts BEL. Emit ST, accept both. Query replies are also ST/BEL terminated."
    },
    "params": [
      {
        "id": "set",
        "anchor": "#set",
        "name": "Set clipboard",
        "meaning": "OSC 52 ; Pc ; <base64> ST sets clipboard Pc to the base64-decoded bytes. Pc: 'c' = CLIPBOARD, 'p' = PRIMARY, 'q' = secondary, 's' = select, '0'-'7' = cut-buffers; empty Pc defaults to CLIPBOARD+PRIMARY. The data field is standard base64 of the raw clipboard bytes.",
        "required": false,
        "byte_sequence_ST": "\u001b]52;c;aGVsbG8=\u001b\\",
        "byte_sequence_ST_readable": "ESC ] 5 2 ; c ; a G V s b G 8 = ESC \\   ==  \\x1b]52;c;aGVsbG8=\\x1b\\\\   (base64 'aGVsbG8=' decodes to 'hello')",
        "byte_sequence_BEL": "\u001b]52;c;aGVsbG8=\u0007",
        "byte_sequence_BEL_readable": "ESC ] 5 2 ; c ; a G V s b G 8 = BEL   ==  \\x1b]52;c;aGVsbG8=\\x07",
        "subparams": []
      },
      {
        "id": "query",
        "anchor": "#query",
        "name": "Query clipboard",
        "meaning": "OSC 52 ; Pc ; ? ST asks the terminal to report the current contents of clipboard Pc. The terminal replies with OSC 52 ; Pc ; <base64> ST containing the base64-encoded clipboard data (if querying is enabled).",
        "required": false,
        "byte_sequence_ST": "\u001b]52;c;?\u001b\\",
        "byte_sequence_ST_readable": "ESC ] 5 2 ; c ; ? ESC \\   ==  \\x1b]52;c;?\\x1b\\\\   (reply e.g. \\x1b]52;c;aGVsbG8=\\x1b\\\\)",
        "byte_sequence_BEL": "\u001b]52;c;?\u0007",
        "byte_sequence_BEL_readable": "ESC ] 5 2 ; c ; ? BEL   ==  \\x1b]52;c;?\\x07",
        "subparams": []
      }
    ],
    "gotchas": [
      "Pd is BASE64, not raw text: you must base64-encode the bytes you want on the clipboard. A bare '?' in the data field means query, not literal data.",
      "SECURITY: clipboard WRITE lets remote programs (e.g. over ssh) silently change your local clipboard; clipboard READ (the '?' query) lets a remote program EXFILTRATE your clipboard. xterm disables both by default (the 'allowWindowOps' / clipboard resources); many terminals disable read in particular and cap the payload size.",
      "Some terminals impose a maximum payload length (xterm has a limit; tmux historically capped OSC 52 around 74 KB / 100 KB depending on version) — large copies may be silently truncated.",
      "Through tmux/screen the sequence must be passed through (tmux 'set-clipboard on' and DCS pass-through); otherwise the multiplexer swallows it.",
      "Base64 with or without trailing '=' padding: emit standard padded base64; some terminals are lenient, others strict.",
      "There is no standard clipboard-MIME negotiation; you set/get raw bytes only."
    ],
    "v1_smoke_test": {
      "asserts": "OSC 52 set (with base64 payload) and query ('?') forms are syntactically valid OSC strings in both ST and BEL terminator forms.",
      "behavioral_conformance": "deferred to v2."
    }
  },
  "updated": "2026-05-29T00:00:00Z"
}