---
title: Squash
description: Squash commits in the pull request.
---

The `squash` action instructs Mergify to squash all commits from a pull request
into one.

When you add this action to a rule, Mergify will squash all the commits from
the pull request into one commit, making the history of your project cleaner
and easier to read.

Squashing writes the pull request's head branch, so the [restrictions on writing
a fork's branch](/workflow/actions/update#fork-pull-requests) apply here too.

## Impersonation

Squashing force-pushes the head branch, and Mergify does that as a GitHub user
rather than as itself. With no
[`bot_account`](/configuration/data-types#bot-account) set, that user is the
pull request author, or whoever posted the [`@mergifyio squash`
command](/commands/squash) when a command triggered the squash. The account must
have signed in to the [Mergify dashboard](https://dashboard.mergify.com) at
least once.

That account cannot be a bot: Mergify cannot impersonate an account owned by
another GitHub App. The action fails whenever the account it falls back to is
one, whether a GitHub App opened the pull request, such as a dependency update
bot, or posted the command. Set `bot_account` to a user account to squash those.

## Parameters

| Key name | Value type | Default | Description |
| --- | --- | --- | --- |
| `bot_account` | simple-template or null | `null` | Mergify can impersonate a GitHub user to squash a pull request. If no `bot_account` is set, Mergify picks the pull request author, or the user who sent the `@mergifyio squash` command. The user account must have already been logged in Mergify dashboard once.  **Warning:** Because of GitHub's security restrictions, Mergify cannot impersonate an account owned by another GitHub App. A squash therefore fails whenever the account it falls back to is a bot, either because the pull request was opened by one or because one sent the command, unless `bot_account` names a user account. |
| `commit_message` | `all-commits` or `first-commit` or `title+body` | `"all-commits"` | Defines what commit message to use for the squashed commit if no commit message is defined in the pull request body. Possible values are:  - `all-commits` to use the same format as GitHub squashed merge commit. - `first-commit` to use the message of the first commit of the pull request. - `title+body` means to use the title and body from the pull request itself as the commit message. The pull request number will be added to end of the title. |

## Examples

### Squash on Label

In this example, whenever there's a label `to-squash` added, any new commits
pushed to the branch will be squashed into a single commit:

```yaml
pull_request_rules:
  - name: automatic squash of pull requests
    conditions:
      - label = to-squash
    actions:
      squash:
```