> ## Documentation Index
> Fetch the complete documentation index at: https://docs.wuji.tech/llms.txt
> Use this file to discover all available pages before exploring further.

# Data Subscription

> Subscribe to real-time data streams and capture them to files with sub

## Subscribe to a Topic

`wuji sub <topic>` subscribes to a device's real-time data. By default it keeps subscribing until Ctrl+C. Add `--count N` to exit automatically after receiving N frames:

```bash theme={null}
wuji sub emf_poses --count 1             # exit after 1 frame
wuji sub tactile --count 10 --sn <SN>    # 10 frames from a specific device
wuji sub imu_data/palm --count 1 --jsonl # one compact JSON object per frame
```

List subscribable topics with `wuji resources` — the command output is the authoritative list. Frequently used topics:

| Topic | Description |
| - | - |
| `tactile` | Tactile matrix |
| `emf_poses` | EMF poses |
| `imu_data/palm` | IMU data |
| `tip_poses` | Fingertip poses |
| `hand_joint_angles` | Joint angles |
| `hand_skeleton` | Hand skeleton |
| `tf` | Coordinate transforms |

## Capture Data to Files

With `--jsonl`, each frame prints as one compact JSON line — pipe it for lightweight recording:

```bash theme={null}
wuji sub tactile --count 500 --jsonl > tactile.jsonl          # silent capture
wuji sub emf_poses --count 500 --jsonl | tee emf.jsonl | jq   # capture while watching
```

Exit code 0 means all requested frames arrived, and nonzero means the subscription failed — ready for script assertions.


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