git-merge
git-merge is a fundamental command in the Git version control system, designed to integrate changes from one branch into another. Here is an in-depth look at this command:
Functionality
- Merge: The primary function of git-merge is to merge one or more commits from a source branch into the current branch. This process can be either:
- Fast-forward: If the merge results in a linear history, where the source branch is ahead of the target branch, Git can simply move the pointer of the target branch forward to the tip of the source branch.
- Three-way Merge: When the histories have diverged, Git uses a three-way merge algorithm to create a new commit that incorporates changes from both branches, resolving conflicts if they occur.
- Conflict Resolution: If Git encounters conflicts during the merge, it marks the files where conflicts occurred, allowing the user to resolve these manually before completing the merge.
History and Context
- Introduced with Git in 2005, git-merge has been a core part of Git's functionality, reflecting Git's design philosophy of distributed version control where branches are cheap to create and merge.
- Its development has been influenced by:
- The need for efficient merging in large projects with many contributors.
- Improvements in conflict detection and resolution strategies.
Command Usage
git merge <branch>
Where <branch> is the name of the branch to be merged into the current branch.
Options and Features
- --no-ff: Prevents Git from performing a fast-forward merge, even if possible, creating a merge commit.
- --squash: Combines all changes from the source branch into one commit on the target branch, without creating a merge commit.
- --abort: Aborts the current merge process and returns the branch to its pre-merge state.
- -m or --message: Allows specifying a custom commit message for the merge commit.
Advanced Usage
- Merging with subtree strategy for integrating repositories as subdirectories.
- Recursive merge strategy for merging branches with complex histories.
External Resources
Related Topics