{
  "id": "terminal-csi/cuu",
  "family": "terminal-csi",
  "slug": "cuu",
  "title": "CSI CUU / CUD / CUF / CUB — Relative Cursor Moves",
  "summary": "The four relative cursor-move commands shift the cursor by Pn cells (default 1) in one direction: CUU (final 'A') up, CUD ('B') down, CUF ('C') forward/right, CUB ('D') back/left. They do not scroll and stop at the screen edge.",
  "kind": "control-sequence",
  "aliases": [
    "CUU",
    "CUD",
    "CUF",
    "CUB",
    "cursor up",
    "cursor down",
    "cursor forward",
    "cursor back",
    "ESC [ A"
  ],
  "status": "standard",
  "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: CSI Ps A = Cursor Up Ps (CUU); CSI Ps B = Cursor Down (CUD); CSI Ps C = Cursor Forward (CUF); CSI Ps D = Cursor Backward (CUB). Default Ps = 1."
    },
    {
      "claim_ref": "ext.params",
      "source_url": "https://ecma-international.org/publications-and-standards/standards/ecma-48/",
      "source_version": "ECMA-48 5th ed. 1991 (ISO/IEC 6429), clauses 8.3.22 (CUU), 8.3.19 (CUD), 8.3.20 (CUF), 8.3.18 (CUB)",
      "note": "ECMA-48 defines CUU/CUD/CUF/CUB with a single Pn parameter defaulting to 1."
    }
  ],
  "see_also": [
    "terminal-csi/cup",
    "terminal-csi/cnl",
    "terminal-csi/cha"
  ],
  "ext_type": "terminal-escape@1",
  "ext": {
    "csi_or_osc": "CSI",
    "command_number": "CUU",
    "frame": {
      "introducer_7bit": "\u001b[",
      "introducer_7bit_readable": "ESC [ (0x1B 0x5B)",
      "introducer_8bit": "›",
      "introducer_8bit_readable": "0x9B (single-byte CSI, 8-bit C1)",
      "note": "CSI + single Pn + final byte: 'A' up, 'B' down, 'C' forward, 'D' back. Pn defaults to 1."
    },
    "terminator": "none",
    "terminator_detail": {
      "note": "No string terminator; the CSI sequence ends at its final byte. Parameters Ps are decimal, ';' (0x3B) separated."
    },
    "params": [
      {
        "id": "cuu",
        "anchor": "#cuu",
        "name": "CUU — Cursor Up (A)",
        "meaning": "CSI Pn A moves the cursor up Pn rows (default 1). Stops at the top of the page; does not scroll.",
        "required": true,
        "byte_sequence_ST": "\u001b[3A",
        "byte_sequence_ST_readable": "ESC [ 3 A   ==  \\x1b[3A   (up 3 rows); \\x1b[A = up 1",
        "subparams": []
      },
      {
        "id": "cud",
        "anchor": "#cud",
        "name": "CUD — Cursor Down (B)",
        "meaning": "CSI Pn B moves the cursor down Pn rows (default 1).",
        "required": false,
        "byte_sequence_ST": "\u001b[3B",
        "byte_sequence_ST_readable": "ESC [ 3 B   ==  \\x1b[3B   (down 3 rows)",
        "subparams": []
      },
      {
        "id": "cuf",
        "anchor": "#cuf",
        "name": "CUF — Cursor Forward (C)",
        "meaning": "CSI Pn C moves the cursor right Pn columns (default 1).",
        "required": false,
        "byte_sequence_ST": "\u001b[3C",
        "byte_sequence_ST_readable": "ESC [ 3 C   ==  \\x1b[3C   (right 3 columns)",
        "subparams": []
      },
      {
        "id": "cub",
        "anchor": "#cub",
        "name": "CUB — Cursor Back (D)",
        "meaning": "CSI Pn D moves the cursor left Pn columns (default 1).",
        "required": false,
        "byte_sequence_ST": "\u001b[3D",
        "byte_sequence_ST_readable": "ESC [ 3 D   ==  \\x1b[3D   (left 3 columns)",
        "subparams": []
      }
    ],
    "gotchas": [
      "A Pn of 0 is treated as 1, not as a no-op, per ECMA-48 default-parameter rules.",
      "These moves CLAMP at the screen edges and never scroll the buffer — to scroll, use SU/SD or move past the scroll region's bottom with newlines.",
      "CUF past the last column does not wrap to the next line; the cursor sticks at the right margin.",
      "Do not confuse CUD ('B') with index/newline: CUD never scrolls, whereas LF/IND can scroll at the bottom margin.",
      "'CSI D' (CUB, back) is distinct from the C0 BS (0x08) backspace though both move left one cell."
    ],
    "v1_smoke_test": {
      "asserts": "CUU/CUD/CUF/CUB render as byte-exact single-parameter CSI sequences with final bytes A/B/C/D.",
      "behavioral_conformance": "deferred to v2."
    }
  },
  "updated": "2026-05-29T00:00:00Z"
}