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Nuggit: Manually change your default branch name

So I was on my laptop running an ancient release of Linux called Fedora 30 -- so old COVID wasn't even a twinkle in a bat's eye when it was released.

On this ancient OS I'm have git 2.21.3 which is like 13 versions behind. I ask yum -- err dnf -- if there is an upgrade and it's like "nope". Nothing makes me feel older than software.

I've gotten into the habit of naming my default branches main instead of master because every time I say "master" I need to take a shower. I'm pretty sure the latest git names the default branch main out of the box, but git from April 2019 was not aware of problematic language choices.

So as one does I'm starting a new repo and I decide before updating git, which is gonna require like 3 Fedora upgrades, I'm just going to rename the branch. I know I'll get woke-git if I upgrade Fedora, but I want to write this post first so we're gonna find a workaround.

[branch:master]$ git branch -m main
error: refname refs/heads/master not found
fatal: Branch rename failed

Hmm. So on a bare repo you can't rename the starting branch because there's no objects in the repo... or something like that waves hands.

Umm... I guess we'll go spelunking into the .git directory to see if we can manually force our main branch naming.

[branch:master]$ cd .git
[.git]$ tree -F
├── branches/
├── config
├── description
├── HEAD
├── hooks/
│   ├── A bunch of sample scripts
├── info/
│   └── exclude
├── objects/
│   ├── info/
│   └── pack/
└── refs/
        ├── heads/
        └── tags/

Well unsurprisingly we have a bunch of empty directories and some sample scripts.

The only files that _might_ be worth looking at are config, description, and HEAD.

// config
        repositoryformatversion = 0
        filemode = true
        bare = false
        logallrefupdates = true

This seems to be config options for this repo, none of which mention branch naming so it's a skip for me.

// description
Unnamed repository; edit this file 'description' to name the repository.

I had no idea this feature existed. I have never seen it be used -- but fun facts!

ref: refs/heads/master

And the money shot. Let's change that bad boy to refs/heads/main and see if my magical git prompt picks it up:

[.git]$ cd ../

Heyo! There you have it. How to manually change the name of your main branch in a fresh git repo.

Sanity check, this won't fuck up if we commit right?

$ cargo init .
$ git add . && git commit -m "initial commit"
[main (root-commit) ebecbee] initial commit
 3 files changed, 12 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Cargo.toml
 create mode 100644 src/main.rs


After anxiously upgrading to Fedora 34 I confirmed that git fixed a lot of this:

[pop@lappy foo]$ git init
hint: Using 'master' as the name for the initial branch. This default branch name
hint: is subject to change. To configure the initial branch name to use in all
hint: of your new repositories, which will suppress this warning, call:
hint:   git config --global init.defaultBranch <name>
hint: Names commonly chosen instead of 'master' are 'main', 'trunk' and
hint: 'development'. The just-created branch can be renamed via this command:
hint:   git branch -m <name>

And yes, git branch -m <name> does work on an empty repo.