I regularly find the need to switch branches in my local Git repos for code reviews or to work on another feature or bug within a project. In the past, I would have either cloned a new copy of the repo or stashed any changes which were not ready to commit. Neither of these is ideal as a new copy is wasteful, as checking out a large repo can take a while and stashing changes is quite disruptive to your current context.
Worktree
Git 2.5 introduced the worktree command, which can be used to checkout multiple working trees from the same local repo. In short this gives you as many different branches as you like checked out to multiple directories at the same time, all pointing to the same local Git repo. This means no wasting disk space on multiple copies of Git meta data and best of all, each worktree is instantly aware of any changes committed from another worktree.
Usage
Code Reviews
For this example, let’s assume the original checkout is on a feature branch that I’m working on and a colleague asks me to review a feature before it’s merged.
$ git worktree add newfeature -b newfeature origin/newfeature
This will create a new directory newfeature in the root of the existing repo, containing the newfeature branch from origin. At this point, the new feature can be reviewed without loosing the context of the develop branch or even any open files.
Once the review is complete, the newfeature directory can be deleted and the worktree pruned:
$ rm -rf newfeature
$ git worktree prune
Bug Fixing
For me, the other major use case of the worktree command is for bug fixing. In the following example, the original checkout is on a feature branch and we want to start a new branch for a bugfix:
$ git worktree add bugfix -b bugfix develop
$ cd bugfix
In this command, a new directory called bugfix is created on a new branch with the same name. The last parameter tells Git to base the new branch on the existing develop branch.
We then cd into the bugfix directory and can implement the bug fix. Once the bugfix is committed, the branch is ready to be merged back to develop:
$ git commit -a
$ git checkout develop
$ git merge bugfix
The worktree can then be removed and the branch deleted:
$ git branch -d bugfix
$ cd ../
$ rm -rf bugfix
$ git worktree prune
At the time of writing, worktree is still quite new and as such is considered experimental. It also does not yet support the full functionality of Git, such as submodules, in multiple checkouts and the documentation suggests a few features which could be added in the future.
Even with the above limitations, worktree can be useful when a quick fix needs to be made or for reviewing another branch.