# PUBSUB

> Inspect pub/sub state.

Use `PUBSUB` to inspect the state of the pub/sub system without subscribing to anything.

`CHANNELS` lists the channels that currently have at least one subscriber, optionally filtered by a glob-style pattern. `NUMSUB` reports the subscriber count for each channel you name, and `NUMPAT` reports how many distinct patterns are subscribed to across all clients.

Only exact-channel subscriptions are counted by `CHANNELS` and `NUMSUB`: a client subscribed with [`PSUBSCRIBE`](/redis/commands/pub-sub/psubscribe) will receive matching messages but does not make a channel appear as active. Use these forms for monitoring and debugging, for instance to confirm that a consumer is really attached before publishing.

## Syntax

```redis
PUBSUB CHANNELS [pattern]
PUBSUB NUMSUB [channel ...]
PUBSUB NUMPAT
```

## Arguments

| Argument | Required | Repeatable | Description |
| --- | --- | --- | --- |
| `CHANNELS [pattern]` | One form | No | List active channels, optionally filtered by a glob-style pattern. |
| `NUMSUB [channel ...]` | One form | Yes | Return subscriber counts for the supplied channels. |
| `NUMPAT` | One form | No | Return the number of active pattern subscriptions. |

## Response

The reply reports the result of the operation. Error replies have the same shape in RESP2 and RESP3 and are surfaced as exceptions by the SDKs below.

| Protocol | Reply |
| --- | --- |
| RESP2 | Array of channel names, flat channel/count array, or Integer |
| RESP3 | Array of channel names, flat channel/count array, or Integer |

<Note>
  Client libraries often decode bulk strings, maps, sets, and numeric strings into language-native values. The table describes the Redis wire reply.
</Note>

## Examples

TCP examples use the TLS `REDIS_URL` from the Upstash console. REST examples use `UPSTASH_REDIS_REST_URL` and `UPSTASH_REDIS_REST_TOKEN`.

<AccordionGroup>

<Accordion title="Redis CLI" icon="terminal">

```bash
PUBSUB CHANNELS events:*
```

</Accordion>

<Accordion title="@upstash/redis" icon="node-js" iconType="brands">

<Note>
  This command is not supported yet in `@upstash/redis`.
</Note>

</Accordion>

<Accordion title="upstash_redis" icon="python" iconType="brands">

<Note>
  This command is not supported yet in `upstash_redis`.
</Note>

</Accordion>

<Accordion title="ioredis" icon="node-js" iconType="brands">

```ts
import Redis from "ioredis";

const redis = new Redis(process.env.REDIS_URL!);
const result = await redis.pubsub("CHANNELS", "events:*");
console.log(result);
```

</Accordion>

<Accordion title="node-redis" icon="node-js" iconType="brands">

```ts
import { createClient } from "redis";

const client = await createClient({ url: process.env.REDIS_URL })
  .on("error", console.error)
  .connect();
const result = await client.pubSubChannels("events:*");
console.log(result);
```

</Accordion>

<Accordion title="redis-py" icon="python" iconType="brands">

```python
import os
import redis

client = redis.from_url(os.environ["REDIS_URL"])
result = client.pubsub_channels("events:*")
print(result)
```

</Accordion>

<Accordion title="go-redis" icon="golang" iconType="brands">

```go
package main

import (
    "context"
    "fmt"
    "os"

    "github.com/redis/go-redis/v9"
)

func main() {
    opts, err := redis.ParseURL(os.Getenv("REDIS_URL"))
    if err != nil {
        panic(err)
    }
    client := redis.NewClient(opts)
    result, err := client.PubSubChannels(context.Background(), "events:*").Result()
    if err != nil {
        panic(err)
    }
    fmt.Println(result)
}
```

</Accordion>

<Accordion title="jedis" icon="java" iconType="brands">

```java
import java.net.URI;

import redis.clients.jedis.Jedis;

try (Jedis jedis = new Jedis(new URI(System.getenv("REDIS_URL")))) {
  Object result = jedis.pubsubChannels("events:*");
  System.out.println(result);
}
```

</Accordion>

<Accordion title="redis-rs" icon="rust" iconType="brands">

```rust
fn main() -> redis::RedisResult<()> {
    let url = std::env::var("REDIS_URL").expect("REDIS_URL is not set");
    let client = redis::Client::open(url)?;
    let mut connection = client.get_connection()?;

    let mut command = redis::cmd("PUBSUB");
    command.arg("CHANNELS");
    command.arg("events:*");
    let result: redis::Value = command.query(&mut connection)?;
    println!("{result:?}");
    Ok(())
}
```

</Accordion>

</AccordionGroup>