# Compare and merge branches in AWS CodeCommit
<a name="how-to-compare-branches"></a>

You can use the CodeCommit console to compare branches in a CodeCommit repository. Comparing branches helps you quickly view the differences between a branch and the default branch, or view the differences between any two branches.

**Topics**
+ [

## Compare a branch to the default branch
](#how-to-compare-branches-default)
+ [

## Compare two specific branches
](#how-to-compare-branches-two)
+ [

## Merge two branches (AWS CLI)
](#how-to-merge-branches-cli)

## Compare a branch to the default branch
<a name="how-to-compare-branches-default"></a>

Use the CodeCommit console to quickly view the differences between a branch and the default branch for your repository.

1. Open the CodeCommit console at [https://console.aws.amazon.com/codesuite/codecommit/home](https://console.aws.amazon.com/codesuite/codecommit/home).

1. In **Repositories**, choose the name of the repository where you want to compare branches. 

1. In the navigation pane, choose **Commits**, and then choose the **Compare commits** tab.

1. In **Destination**, choose the name of the default branch. In **Source**, choose the branch you want to compare to the default branch. Choose **Compare**.

## Compare two specific branches
<a name="how-to-compare-branches-two"></a>

Use the CodeCommit console to view the differences between two branches that you want to compare.

1. Open the CodeCommit console at [https://console.aws.amazon.com/codesuite/codecommit/home](https://console.aws.amazon.com/codesuite/codecommit/home).

1. In **Repositories**, choose the name of the repository where you want to compare branches. 

1. In the navigation pane, choose **Commits**, and then choose the **Compare commits** tab.

1. In **Destination** and **Source**, choose the two branches to compare, and then choose **Compare**. To view the list of changed files, expand the changed files list. You can view changes in files side by side (Split view) or inline (Unified view).
**Note**  
If you are signed in as an IAM user, you can configure and save your preferences for viewing code and other console settings. For more information, see [Working with user preferences](user-preferences.md).  
![\[An abbreviated view of the differences between two branches.\]](http://docs.aws.amazon.com/codecommit/latest/userguide/images/codecommit-compare-branches.png)

## Merge two branches (AWS CLI)
<a name="how-to-merge-branches-cli"></a>

You can merge two branches in a CodeCommit repository using the AWS CLI using one of the available merge strategies by running one of the following commands:
+ To merge two branches using the fast-forward merge strategy, run the [**merge-branches-by-fast-forward**](#merge-branches-by-fast-forward) command.
+ To merge two branches using the squash merge strategy, run the [**merge-branches-by-squash**](#merge-branches-by-squash) command.
+ To merge two branches using the three-way merge strategy, run the [**merge-branches-by-three-way**](#merge-branches-by-three-way) command.

You can also test merges by running the **create-unreferenced-merge-commit** command. For more information, see [Resolve Conflicts in a Pull Request](how-to-resolve-conflict-pull-request.md#create-unreferenced-merge-commit).

**Note**  
To use AWS CLI commands with CodeCommit, install the AWS CLI. For more information, see [Command line reference](cmd-ref.md). 

**To use the AWS CLI to merge two branches in a CodeCommit repository**

1. <a name="merge-branches-by-fast-forward"></a>To merge two branches using the fast-forward merge strategy, run the **merge-branches-by-fast-forward** command, specifying: 
   + The name of the source branch that contains the changes you want to merge (with the **--source-commit-specifier** option). 
   + The name of the destination branch where you want to merge your changes (with the **--destination-commit-specifier** option). 
   + The name of the repository (with the **--repository-name** option).

    For example, to merge a source branch named *bugfix-1234* into a destination branch named *preprod* in a repository named *MyDemoRepo*:

   ```
   aws codecommit merge-branches-by-fast-forward --source-commit-specifier bugfix-bug1234 --destination-commit-specifier preprod --repository-name MyDemoRepo
   ```

   If successful, this command produces output similar to the following:

   ```
   {
       "commitId": "4f178133EXAMPLE",
       "treeId": "389765daEXAMPLE"
   }
   ```

1. <a name="merge-branches-by-squash"></a>To merge two branches using the squash merge strategy, run the **merge-branches-by-squash** command, specifying:
   + The name of the source branch that contains the changes you want to merge (with the **--source-commit-specifier** option). 
   + The name of the destination branch where you want to merge your changes (with the **--destination-commit-specifier** option). 
   + The name of the repository (with the **--repository-name** option).
   + The commit message to include (with the **--commit-message** option).
   + The name to use for the commit (with the **--name** option).
   + The email address to use for the commit (with the **--email** option).

   For example, to merge a source branch named *bugfix-bug1234* with a destination branch named *bugfix-quarterly* in a repository named *MyDemoRepo*:

   ```
   aws codecommit merge-branches-by-squash --source-commit-specifier bugfix-bug1234 --destination-commit-specifier bugfix-quarterly --author-name "Maria Garcia" --email "maria_garcia@example.com" --commit-message "Merging in fix branches to prepare for a general patch." --repository-name MyDemoRepo
   ```

   If successful, this command produces output similar to the following:

   ```
   {
       "commitId": "4f178133EXAMPLE",
       "treeId": "389765daEXAMPLE"
   }
   ```

1. <a name="merge-branches-by-three-way"></a>To merge two branches using the three-way merge strategy, run the **merge-branches-by-three-way** command, specifying:
   + The name of the source branch that contains the changes you want to merge (with the **--source-commit-specifier** option). 
   + The name of the destination branch where you want to merge your changes (with the **--destination-commit-specifier** option). 
   + The name of the repository (with the **--repository-name** option).
   + The commit message to include (with the **--commit-message** option).
   + The name to use for the commit (with the **--name** option).
   + The email address to use for the commit (with the **--email** option).

   For example, to merge a source branch named *main* with a destination branch named *bugfix-1234* in a repository named *MyDemoRepo*:

   ```
   aws codecommit merge-branches-by-three-way --source-commit-specifier main --destination-commit-specifier bugfix-bug1234 --author-name "Jorge Souza" --email "jorge_souza@example.com" --commit-message "Merging changes from main to bugfix branch before additional testing."  --repository-name MyDemoRepo
   ```

   If successful, this command produces output similar to the following:

   ```
   {
       "commitId": "4f178133EXAMPLE",
       "treeId": "389765daEXAMPLE"
   }
   ```