Git cheat sheet

This page is meant as a handy reference for some basic Git commands.

1. After making a local clone of BLT, you can change code in your local BLT/ directory. Git will track these changes. At any time, you can check what git thinks has been changed using:

   $ git status

You can also view diffs of your changes by typing:

   $ git diff

2. To sync your local code with the latest updates from the GitHub repo, run:

  $ git fetch upstream
  $ git merge upstream/master

3. To download a branch someone else created:

   $ git checkout -b {{branch-name}}
   $ git pull https://github.com/{{their-repo-name}}/BLT.git {{branch-name}}

4. To create a patch:

   $ git checkout {{branch-to-patch-from}}
   $ git format-patch -1   # goes back one commit

This should create a file with the extension .patch. The name should include part of the commit message from the change it is patching. You may need to move this file outside BLT/ so that it won't disappear when you switch branches.

5. To apply a patch:

   $ git checkout {{branch-to-patch-to}}
   $ git apply {{patch-file-name}}

6. To squash the last three commits into a single one:

  git reset --soft HEAD~3 &&
  git commit -m "{{YOUR_COMMIT_MESSAGE_HERE}}"

Be careful to only squash "local" commits -- never squash anything that has been uploaded to the codesite before (no matter what branch). In particular, don't squash commits that already have code review comments on them. Also, don't squash any commit that merged two branches.

If you want to squash commits that you previously pushed to GitHub, make a new local branch that includes the small commits, squash the commits locally, and push the new branch instead.

7. To fetch changes of a pull request locally:

  git fetch {{THE REMOTE TO MAIN BLT REPO}} pull/{{PULL REQUEST NUMBER}}/head:{{A NEW BRANCH NAME}}
  git checkout {{NEW BRANCH NAME}}