# Cmux

> Control cmux terminal multiplexer via its Unix socket API. Use when needing to: (1) List, create, select, or close workspaces; (2) Split panes and manage surfaces; (3) Send text or key presses to terminals; (4) Create notifications; (5) Set sidebar status, progress bars, or log entries; (6) Query system state. Requires cmux CLI or Unix socket at /tmp/cmux.sock.

- Skill: `dvcrn/cmux` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add dvcrn/cmux`
- Raw SKILL.md: https://api.skillmd.com/api/skills/dvcrn/cmux/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: dvcrn (https://skillmd.com/u/dvcrn)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/dvcrn/cmux

---


# cmux

Control cmux terminal multiplexer programmatically via its Unix socket API or CLI.

## Socket Connection

```bash
SOCKET_PATH="${CMUX_SOCKET_PATH:-/tmp/cmux.sock}"
```

Send JSON-RPC requests:
```json
{"id":"req-1","method":"workspace.list","params":{}}
```

## CLI Quick Reference

```bash
# Output as JSON
cmux --json <command>

# Target specific workspace/surface
cmux --workspace <id> --surface <id> <command>
```

## Workspace

| Action | CLI | Socket Method |
|--------|-----|---------------|
| List all | `cmux list-workspaces` | `workspace.list` |
| Create new | `cmux new-workspace` | `workspace.create` |
| Select | `cmux select-workspace --workspace <id>` | `workspace.select` |
| Get current | `cmux current-workspace` | `workspace.current` |
| Close | `cmux close-workspace --workspace <id>` | `workspace.close` |

## Splits & Surfaces

| Action | CLI | Socket Method |
|--------|-----|---------------|
| New split | `cmux new-split <direction>` | `surface.split` (direction: left/right/up/down) |
| List surfaces | `cmux list-surfaces` | `surface.list` |
| Focus surface | `cmux focus-surface --surface <id>` | `surface.focus` |

## Input

| Action | CLI | Socket Method |
|--------|-----|---------------|
| Send text | `cmux send "echo hello"` | `surface.send_text` |
| Send key | `cmux send-key enter` | `surface.send_key` |
| Send to surface | `cmux send-surface --surface <id> "cmd"` | `surface.send_text` (with surface_id) |

Keys: `enter`, `tab`, `escape`, `backspace`, `delete`, `up`, `down`, `left`, `right`

## Notifications

```bash
cmux notify --title "Title" --body "Body"
# Socket: notification.create
```

## Sidebar Metadata

| Action | CLI | Socket Method |
|--------|-----|---------------|
| Set status | `cmux set-status <key> <value>` | (socket only) |
| Clear status | `cmux clear-status <key>` | (socket only) |
| Set progress | `cmux set-progress 0.5 --label "Building..."` | (socket only) |
| Clear progress | `cmux clear-progress` | (socket only) |
| Log entry | `cmux log "message" --level error` | (socket only) |
| Clear log | `cmux clear-log` | (socket only) |

## System

| Action | CLI | Socket Method |
|--------|-----|---------------|
| Ping | `cmux ping` | `system.ping` |
| Capabilities | `cmux capabilities` | `system.capabilities` |
| Identify context | `cmux identify` | `system.identify` |

## Python Client

```python
import json
import os
import socket

SOCKET_PATH = os.environ.get("CMUX_SOCKET_PATH", "/tmp/cmux.sock")

def rpc(method, params=None, req_id=1):
    payload = {"id": req_id, "method": method, "params": params or {}}
    with socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) as sock:
        sock.connect(SOCKET_PATH)
        sock.sendall(json.dumps(payload).encode("utf-8") + b"\n")
        return json.loads(sock.recv(65536).decode("utf-8"))

# List workspaces
print(rpc("workspace.list", req_id="ws"))

# Send notification
print(rpc("notification.create", {"title": "Hello", "body": "From Python!"}))
```

## Shell Helper

```bash
cmux_cmd() {
    SOCK="${CMUX_SOCKET_PATH:-/tmp/cmux.sock}"
    printf "%s\n" "$1" | nc -U "$SOCK"
}

cmux_cmd '{"id":"ws","method":"workspace.list","params":{}}'
```

## Check if cmux is Available

```bash
[ -S "${CMUX_SOCKET_PATH:-/tmp/cmux.sock}" ] && echo "cmux socket available"
command -v cmux &>/dev/null && echo "cmux CLI available"
```