packer/website/content/docs/templates/hcl_templates/functions/collection/concat.mdx

---
page_title: concat function reference
description: The `concat` function combines two or more lists into a single list. Learn how to use the `concat` function in Packer templates.
---

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> [!IMPORTANT]  
> **Documentation Update:** Product documentation previously located in `/website` has moved to the [`hashicorp/web-unified-docs`](https://github.com/hashicorp/web-unified-docs) repository, where all product documentation is now centralized. Please make contributions directly to `web-unified-docs`, since changes to `/website` in this repository will not appear on developer.hashicorp.com.
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# `concat` Function

`concat` takes two or more lists and combines them into a single list.

## Examples

```shell-session
> concat(["a", ""], ["b", "c"])
[
  "a",
  "",
  "b",
  "c",
]
```