---
title: Program Command Block Minecart
description: "Play 0x37, client → server."
---

`play` · `0x37` · **serverbound** (client → server)

Sent when the player saves the GUI of a command block minecart with `entityId`. `command` is the command text and `track_output` controls whether the last output is stored. Operator-only; the server updates the minecart.

Sent by the client, read by the server. Listen for it with `client.on("ProgramCommandBlockMinecart", (data) => …)` on the receiving side.

## Fields

| Field | Type | Notes |
|---|---|---|
| `entityId` | VarInt |  |
| `command` | String |  |
| `track_output` | Boolean |  |

## Send it

```ts
await client.sendPacket("ProgramCommandBlockMinecart", {
  entityId: /* VarInt */,
  command: /* String */,
  track_output: /* Boolean */,
});
```

Field aliases listed under Notes are accepted as alternative keys when writing.

Source: [`src/Core/Versions/776/Packets/play/serverbound/ProgramCommandBlockMinecart.ts`](https://github.com/GDLev/mc-protocol/blob/master/src/Core/Versions/776/Packets/play/serverbound/ProgramCommandBlockMinecart.ts)