# HELLO

> Handshake with Redis protocol.

Use `HELLO` to negotiate the protocol version of the connection and read the server handshake information.

Passing `<protover>` switches the connection to RESP2 or RESP3. RESP3 adds native map, set, double, and push replies, so commands such as [`HGETALL`](/redis/commands/hash/hgetall) or [`CONFIG GET`](/redis/commands/server/config-get) come back as maps instead of flat arrays, and pub/sub messages arrive as push replies that do not block ordinary commands. `AUTH` authenticates in the same call and `SETNAME` names the connection, which lets a client complete its handshake in one round trip.

Called without arguments, `HELLO` only reports the server version, the protocol in use, the connection id, and the current role, leaving the protocol unchanged.

## Syntax

```redis
HELLO
  [<protover>
    [AUTH <username> <password>]
    [SETNAME <clientname>]]
```

## Arguments

| Argument | Required | Repeatable | Description |
| --- | --- | --- | --- |
| `<protover> [AUTH <username> <password>] [SETNAME <clientname>]` | No | No | Protocol version to switch to, optionally with credentials and a connection name. |

## Important points

- This is a connection-oriented command and is available over native Redis TCP, not the stateless REST endpoint.

## 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 | Flat array of alternating keys and values |
| RESP3 | Map |

<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
HELLO
```

</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.hello();
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.hello();
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.hello()
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.Do(context.Background(), "HELLO").Result()
    if err != nil {
        panic(err)
    }
    fmt.Println(result)
}
```

</Accordion>

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

```java
import java.net.URI;
import java.nio.charset.StandardCharsets;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.commands.ProtocolCommand;

ProtocolCommand command = () -> "HELLO".getBytes(StandardCharsets.UTF_8);
try (Jedis jedis = new Jedis(new URI(System.getenv("REDIS_URL")))) {
  Object result = jedis.sendCommand(command);
  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("HELLO");

    let result: redis::Value = command.query(&mut connection)?;
    println!("{result:?}");
    Ok(())
}
```

</Accordion>

</AccordionGroup>