How to use the command 'git cherry' (with examples)

git cherry is a command-line tool provided by Git, a widely-used version control system. The git cherry command is particularly useful for determining which commits from your local branch have not yet been applied to a given upstream branch. This command can be instrumental when coordinating work between multiple contributors or making sure that all desired changes have been incorporated from or to a certain branch. By comparing two branches, git cherry helps identify commits that have been diverged and assists in maintaining a streamlined and manageable workflow.

Use case 1: Show commits (and their messages) with equivalent commits upstream

Code:

git cherry -v

Motivation:

When working with multiple branches, especially in collaborative projects, keeping track of changes can be overwhelming. This command is helpful in reviewing which commits have already been applied to the upstream branch, facilitating a better understanding of which changes have been integrated, and helping to avoid redundant work or re-integration of the same features.

Explanation:

• git cherry: The base command being used to identify unmerged commits.
• -v or --verbose: This option provides a detailed output, showing not just the commit identifiers but also their commit messages. This verbosity aids developers in a clearer insight into the nature of the commits without needing to look up each commit ID separately.

Example Output:

- 124abcd This commit exists in both branches
- 567efgh Another commit from upstream
+ 890ijkl A unique commit to this branch

Here, the prefix - indicates that those commits are present in both local and upstream branches, whereas + denotes commits present only in the local branch.

Use case 2: Specify a different upstream and topic branch

Code:

git cherry origin topic

Motivation:

Sometimes, the upstream branch we need to compare against might not be the default. For instance, developers might work on feature branches (topic branches) and compare these changes with the origin (which may be main or develop), which serves as a primary integration branch. This allows for flexible branch comparison, assisting developers in aligning features before they attempt to merge.

Explanation:

• git cherry: The main command for identifying unmatched commits.
• origin: This argument specifies the designated upstream reference, which is typically the remote branch against which the comparison is made.
• topic: This identifies the local feature branch (or any specific branch) you want to compare against the specified upstream. By stating both origin and topic, you can dynamically assess which local branch changes have not yet been merged upstream.

Example Output:

- 903abcd Unmerged commit in upstream
+ 321tuvw New local feature
+ 456xyz A local bug fix not yet upstream

In this output, + represents the list of commits local to the topic branch and not found in origin, whereas - indicates those available in both branches.

Use case 3: Limit commits to those within a given limit

Code:

git cherry origin topic base

Motivation:

In some scenarios, constraining the comparison to a specific timeframe or a number of commits is critical, particularly when handling large projects where revisiting a multitude of changes is cumbersome. This command allows you to limit the scope of the search to those commits applied after a specific point, the base, providing more focused results.

Explanation:

• git cherry: The command for detailing commits yet to be applied upstream.
• origin: The upstream branch to which you are comparing.
• topic: The local branch of interest for commit evaluation.
• base: This parameter acts as the reference point in the commit history, restricting the comparison to only those commits ahead of the specified base. It serves as an anchor in a project’s commit history from which changes in topic are assessed relative to origin.

Example Output:

+ 126halm Commit added after base
+ 347scan Additional unique commit since base

The results show + for commits that are found only on the topic branch beyond the base point, providing a clear oversight of newly added features or fixes requiring upstream integration.

Conclusion:

The git cherry command is a valuable utility in a developer’s toolkit for efficiently tracking and managing commit status between branches. By using different options and configurations, developers can streamline their workflow, enhance collaboration, and ensure that all essential changes are properly propagated to the central repository. Its ability to succinctly report unmerged commits in combination with specified branches and markers makes it indispensable for effective version control management.