Tag Archives: Git

Git: Undo last commit

Sometimes I forget to create a new feature branch, and accidentally commit to master. Keep having to look up how to fix it…

# From master, create new branch, which will include the accidental commits
git branch feature/foobar

# Move master HEAD back, which will remove the commits from there
git reset --hard HEAD~1

# Checkout feature branch, where the commits should still exist
git checkout feature/foobar

Heroku deploy sub-directory

Going through a couple of Udemy courses, and figured it was nice to keep all the code I wrote while doing them in a single github repository.

Was working nicely until I started the Node with React where part of the course is to deploy the app to Heroku which wants a full repository pushed to a certain git repo it creates for deployment. But in my case the app I want to deploy is of course a sub-directory…

Turns out there’s a git command called subtree one can use here:

# Setup
heroku login
heroku create

git remote add heroku/some-name https://git.heroku.com/{created-heroku-app-id}.git

# Deploy
git subtree push --force --prefix path/to/app heroku/some-name master

The subtree command needs to be run from the top-level directory of the git repository, but one can add a script command to the apps package.json, for example like this:

{
  "scripts": {
    "deploy": "cd ../../.. && git subtree push --prefix path/to/app heroku/some-name master"
  }
}

Unfortunately, subtree push doesn’t support --force, but a workaround for that is running it nested like this:

git push heroku/some-name `git subtree split --prefix path/to/app master`:master --force

Which unfortunately doesn’t work on Windows… but you can do it in two steps instead:

git subtree split --prefix path/to/app master
git push heroku/some-name {id-from-previous-command}:master --force

Stop Git from messing with my newlines

I’m sorry, but I just hate when Git is messing with my files…

warning: CRLF will be replaced by LF in some/file.ext.
The file will have its original line endings in your working directory.

That’s just not its job! If I want to enforce a certain new line regime, there’s linting tools, pre-commit hooks, etc.

The following should stop it, but frankly, sometimes it feels like git just keeps inventing new ways of reverting to its hyper annoying default…

# First run this to see where it's configured now
> git config --list --show-origin

# Then run whichever works...
> git config --global core.autocrlf false
> git config --system core.autocrlf false
> git config --local core.autocrlf false

Using SSH keys with GitHub / BitBucket / Azure DevOps on Windows

Couldn’t get this to work, but now it does, so… time for another “note to self”. 🙂

Prerequisites

  • Git, obviously…
  • PuTTY, with puttygen, plink and pageant, to be exact…

Setup

  1. Open puttygen.

  2. Either Load an existing private key, or Generate a new one.

  3. Copy the public key (“Public key for pasting …”) and add it to the git provider settings:

    • https://github.com/settings/keys
    • https://bitbucket.org/account/user/[username]/ssh-keys/
    • https://dev.azure.com/[organization]/_usersSettings/keys
  4. Open pageant.

  5. Load your private key.

  6. Check that the key authentication works with plink:

    plink -v git@github.com
    plink -v git@bitbucket.org
    plink -v git@ssh.dev.azure.com
  7. Set the GIT_SSH environment variable to C:\Program Files\PuTTY\plink.exe.

    ^^ This is the detail that so many StackOverflow answers and blog/forum posts didn’t mention. Without this, plink worked fine, but git commands still failed with authentication errors.

  8. (optional) Add a shortcut to the private key file to your startup folder. This way pageant will be automatically started, with your key, ready to go, whenever Windows boots up.

    start shell:startup

Usage

Now, as long as pageant is running with your private key loaded, it should work to clone, pull, push, etc., both to and from, both private and public git repositories. E.g. like this:

git clone git@github.com:example/some-private-repo.git

Note: If you’re asked to accept/store/cache a key, but pressing y doesn’t work, connect using putty first, which should give you a dialog with the same question which does work. Putty will complain/crash because there’s not actually an ssh shell to connect to, but that’s fine. After the key has been saved by putty, git should work fine. E.g. like this:

putty -ssh git@github.com

Sources: makandracards.com, vladmihalcea.com