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

# 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`](/docs/redis/commands/hash/hgetall) or [`CONFIG GET`](/docs/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 theme={"system"}
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 theme={"system"}
    HELLO
    ```
  </Accordion>

  <Accordion title="ioredis" icon="node-js" iconType="brands">
    ```ts theme={"system"}
    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 theme={"system"}
    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 theme={"system"}
    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 theme={"system"}
    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 theme={"system"}
    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 theme={"system"}
    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>


## Related topics

- [MSET](/docs/redis/commands/string/mset.md)
- [$regex](/docs/redis/search/query-operators/field-operators/regex.md)
- [Using AWS SAM](/docs/redis/tutorials/using_aws_sam.md)
- [EVALSHA](/docs/redis/commands/scripting/evalsha.md)
- [ECHO](/docs/redis/commands/connection/echo.md)