# How to produce records to a topic in Redpanda from a shell script?

By Bobby Iliev, 2022-02-09. https://bobbyiliev.com/post/how-to-produce-records-to-a-topic-in-redpanda-from-a-shell-script/

## Introduction

[Redpanda](https://redpanda.com/) is a Kafka-compatible event stream platform written in C++.

It comes with a simple command-line interface called `rpk` that lets you interact with the platform.

In this tutorial, we will be using the `rpk` command-line interface to produce events to a topic in Redpanda from a shell script. If topics and partitions are new to you, the [message queue simulator](https://devops-daily.com/games/message-queue-simulator) shows how they work.

## Setup

You can follow the instructions from the Redpanda documentation to install Redpanda and the `rpk` command-line interface:

- [Getting Started with Redpanda](https://docs.redpanda.com/docs/getting-started) 

Once you have installed Redpanda and the `rpk` command-line interface you would also have to install the `jq` command-line utility:

- [How to work with JSON in BASH using jq](/post/how-to-work-with-json-in-bash-using-jq/)

## Create a topic

To create a topic you need to run the following command:

```
rpk topic create my-topic
```

## Produce a record

As stated in the [Redpanda documentation](https://docs.redpanda.com/docs/reference/rpk-commands#rpk-topic-produce) the producing records reads from STDIN. You can produce a record to a topic by running the following command:

```
rpk record produce my-topic

// Then type the record that you want to produce e.g.:
// '{"key": "value"}'
```

## Shell script

The above command produces a record to a topic ad hoc, however, you can also produce a record to a topic using a shell script too.

Here are a few examples of how to produce a record to a topic:

### Produce a record to a topic using `jq`

First, start by creating your message in JSON format:

```
JSON_STRING=$( jq -n --arg id "$ID" --arg name "user_$ID" '{id: $id, name: $name}' ) ;
```

Then you can produce a record to a topic using the `rpk` command-line interface:

```
echo "$JSON_STRING" | rpk record produce my-topic
```

To put this into a demo script that generates random user IDs and names in a loop you can use the following:

```bash
#!/bin/bash

# Create Redpanda topic
rpk topic create demo

# Counter for the id
ID=1

# Infinite loop to produce data
while true ; do
    JSON_STRING=$( jq -n --arg id "$ID" --arg name "user_$ID" '{id: $id, name: $name}' );
    # Send the message
    echo ${JSON_STRING} ; done | rpk topic produce demo

    # Increment the id
    ID=$((id+1))
done
```

### Produce a record to a topic from a file

If you already have a file with the message you want to produce you can use the `rpk` command-line interface to produce a record to a topic:

```
cat messages.json | rpk record produce my-topic
```

## Conclusion

For more information about Redpanda and the `rpk` command-line interface, you can visit the [Redpanda documentation](https://docs.redpanda.com/docs/reference/rpk-commands).

To see Redpanda in action, make sure to check out this demo here:

- [Redpanda + Materialize Demo](https://github.com/MaterializeInc/ecommerce-demo/blob/main/README_RPM.md)

Happy coding!