# Define and use variables

Octopus lets you define variables and scope them for use in different phases of your deployments. Variables allow you to have a consistent deployment process across your infrastructure without having to hard-code or manually update configuration settings that differ across environments, deployment targets, channels, or tenants.

## Add a variable

1. From the *Hello world* project you created earlier, click **Project Variables** in the left menu.
2. Click **Create Variables**.
3. Add `Helloworld.Greeting` in the **Name** column,
4. Add `Hello, Development` in the **Value** column, 
5. Click the **Scope** column and select the `Development` environment.
6. Click **Add another value**.
7. Add `Hello, Staging` and scope it to the `Staging` environment.
8. Click **Add another value**.
9. Add `Hello, Production` and scope it to the `Production` environment.
10. Click **Save**.

:::figure
![The hello world variables](/docs/img/getting-started/first-deployment/images/project-variables.png)
:::

## Update deployment process

Steps in the deployment process can reference variables.

1. Click **Process** in the left menu.
2. Select the previously created **Run a Script** step.

### Inline Source Code

3. Based on your selected language, copy the appropriate script from below.
4. Replace the script in the code editor with the new script.

<details data-group="getting-started-first-deployment-define-and-use-variables">
<summary>PowerShell</summary>

```powershell
Write-Host $OctopusParameters["Helloworld.Greeting"]
```

</details>
<details data-group="getting-started-first-deployment-define-and-use-variables">
<summary>Bash</summary>

```bash
greeting=$(get_octopusvariable "Helloworld.Greeting")
echo $greeting
```

</details>

:::div{.hint}
If you are using Octopus Cloud, Bash scripts require you to select the **Hosted Ubuntu** worker pool.  The **Default Worker Pool** is running Windows and doesn't have Bash installed.
:::

5. Click **Save**
6. Click **Create Release**.

:::div{.hint}
A release snapshots everything about your project, including variables and the deployment process. You have to create a new release to see any changes.
:::
 
As you promote through the environments, you will see the greeting change.

:::figure
![The results of the hello world deployment with variables](/docs/img/getting-started/first-deployment/images/environment-variables.png)
:::

Great job! Next, let's build on your deployment process and [add an approval process using manual interventions](/docs/getting-started/first-deployment/approvals-with-manual-interventions). 

### All guides in this tutorial series

1. [First deployment](/docs/getting-started/first-deployment)
2. Define and use variables (this page)
3. [Approvals with manual interventions](/docs/getting-started/first-deployment/approvals-with-manual-interventions)
4. [Add deployment targets](/docs/getting-started/first-deployment/add-deployment-targets)
5. [Deploy a sample package](/docs/getting-started/first-deployment/deploy-a-package)

### Further reading for variables

- [Variables](/docs/projects/variables)
- [Deployments](/docs/deployments)
- [Patterns and Practices](/docs/deployments/patterns)