The “git prune” command in Git is used for pruning or removing unreachable objects from the object database. Unreachable objects are objects that are no longer referenced by any branch, tag, or commit in the repository’s history.
Typically, the “git prune” command is not used directly by Git users in their everyday workflows. Instead, it is primarily used internally by Git’s garbage collection process, known as “git gc.”
Here’s some additional information about the “git prune” command and its relationship to garbage collection:
- Object Database: Git uses an object database to store all the data in a repository, including commits, trees, and blobs. Over time, as you create and modify objects, the object database can accumulate unreachable or “dangling” objects. These objects are no longer reachable through any references and can consume disk space without serving any purpose.
- Garbage Collection (git gc): Git’s garbage collection is a process that runs periodically or when triggered manually to optimize the object database. It performs various tasks, including removing unreachable objects, compressing loose objects into pack files, and optimizing storage efficiency.
- “git prune”: The “git prune” command is the mechanism used by Git to identify and remove unreachable objects from the object database. It scans the repository’s objects and removes those that are not referenced by any reachable commit, tree, or tag.
- Usage: While “git prune” can be used directly by advanced Git users if necessary, it is primarily executed automatically as part of the “git gc” process. Running “git gc” triggers garbage collection, which, in turn, invokes “git prune” internally to remove the unreachable objects.
By removing unreachable objects, “git prune” helps to keep the object database efficient and maintain optimal repository performance. It reduces the disk space required by the repository, especially in cases where a large number of objects have become unreachable.
git prune Command Examples
1. Report what would be removed by Git prune without removing it:
# git prune --dry-run
2. Prune unreachable objects and display what has been pruned to stdout:
# git prune --verbose
3. Prune unreachable objects while showing progress:
# git prune --progress
Summary
To summarize, “git prune” is a Git command used for removing unreachable objects from the object database. It is typically invoked internally by Git’s garbage collection process, “git gc.” This command helps optimize storage space and maintain repository efficiency.