Cloning a repository

Let's create a pull request! We're going to do that on GitHub, but these instructions should be easy to adopt to any of the various similar code forges.

Forking and cloning

I've got a sample repository that you can fork. We'll be using this repo as an example for this first part of the tutorial. Click "fork" to create a fork of your own.

Next, let's clone down our fork. Go to the directory where you'd like to create your clone, in my case, that's ~/src. And then type this:

$ jj git clone --colocate git@github.com:<YOUR USERNAME>/hello-world
Fetching into new repo in "/home/<YOUR USERNAME>/src/hello-world"
bookmark: trunk@origin [new] untracked
Setting the revset alias "trunk()" to "trunk@origin"
Working copy now at: snwusnyo 3ea00cda (empty) (no description set)
Parent commit      : qvryknuz 5a15ed3b trunk | Hello, world!
Added 4 files, modified 0 files, removed 0 files

You'll want to cd hello-world if you're following along on your own computer.

Just like git clone, jj git clone will clone a remote repository to your local disk. However, we are passing a certain flag to this command, --colocate. jj supports two different kinds of repositories: colocated, and non-colocated. What's the difference? Well, let's take a look at our repository:

$ tree . -a -L 1 --noreport
.
├── .git
├── .gitignore
├── .jj
├── Cargo.lock
├── Cargo.toml
└── src

We have both a .jj and a .git directory at the top level. This means both jj's information as git's information are co-located: they're next to each other. A non-colocated directory stores .git inside of .jj. For your first foray into jj, I strongly recommend a colocated repository, as it allows you to still easily run git commands as well as jj's. This can help ease you into things. It also means tooling that expects to see a .git at the root of the repository will still work.

Looking at history

Let's see what our repository's history looks like:

$ jj log
@  tnmounps steve@steveklabnik.com 2025-02-06 09:43:34 4fed3b0d
│  (empty) (no description set)
◆  ptrqnyzv steve@steveklabnik.com 2024-09-24 12:43:36 trunk git_head() 0c72abbb
│  Hello, world!
~

This looks a bit different than git log, but it's the same general idea: we can see where we our in our history.

There's a lot I could say about this output, but I'd rather show you how to get work done first. Let's make our first change.