Git Worktrees are not so Scary 😱

So worktrees, I always thought they were a big scary things. Turns out they are much simpler than I thought.

Myth #1

no special setup

I thought you had to be all in or worktrees or normal git, but not both. When I see folks go all in on worktrees they start with a bare repo, while its true this is the way you go all in, its not true that this is required.

Lets make a worktree

Making a worktree is as easy as making a branch. It's actually just a branch that lives in another place in your filesystem.

# checkout a new worktree called compare based on main in /tmp/project
git worktree add -b compare /tmp/project main

# checkout a new worktree called compare based on HEAD in /tmp/project
git worktree add -b compare /tmp/project

# checkout a worktree from an existing feature branch in /tmp/project
git worktree add /tmp/project my-existing-feature-branch

The worktree that you create is considered a linked worktree, while the
original worktree is called the main worktree

Note that I put this in my tmp directory because I don't expect it to live very long, my recent use case was to compare two files after a big formatting change. You put these where you want, but dont come at me when your /tmp gets wiped and you loose work.

## Myth #2
they are hidden mysterious creatures

Just like branches git has some nice commands to help us understand what worktrees we have on our system. Firstly we have something very specific to worktrees to list them out.

git worktree list

gives the output

/home/u_walkews/git/git-work-play  b202442 [main]
/tmp/another                       d9b2cf1 [another]

Even the branch command gives a bit different output for a worktree.

git branch

gives this output, notice the + denotes an actively linked worktree, and the * gives the active branch. If you cd over to the worktree directory, these will switch roles.

+ another
  just-a-branch
* main

You can only checkout a branch in one place

If you try to checkout a branch that is checked out in a linked worktree, you will be presented with an error, and it will not let you check out a second copy of that branch.

❯ git checkout another
fatal: 'another' is already checked out at '/tmp/another'

Myth #3

once you go worktree, you worktree

Once you have worktrees on your system, you have a few ways to get rid of them. Using git's way feels much superior, but if your a doof like me and didn't read the manual before you rm /tmp/another -rf you will notice that the worktree is still active. If you run git worktree prune it will clean that right up.

git worktree remove another

rm /tmp/another git worktree prune

It won't let you remove if you have changes

This makes me think that remove is a much safer option. If you have uncommitted changes, git worktree remove will throw an error, and make you commit or use --force to remove the worktree.

❯ git worktree remove another
fatal: 'another' contains modified or untracked files, use --force to delete it

RTFM

read the friendly manual

There is a ton more information in the man page for worktrees, these are just the parts that seemed really useful to me out of the gate.

man git worktree