Source version control with Git

Git is a popular distributed version control system.
Git records changes to your source code over time allowing you to recall specific versions later.

Users work on their local copies of the source code.
A repo is just a directory of files. Deleting a repo = simply deleting that directory.

The above workflow works for a single developer keeping their changes tracked. What happens when another developer committed and push their changes to the remote repo while you were away?

There are several ways of doing this:

git pull which does a combination of 2 steps in order to get latest version of code to your working space.
- git fetch which updates the local repo with content from remote repo (your working directory still does not have the latest remote changes)
- git merge merges the local repo with your working directory.

Alternatively,

git pull --rebase does a fetch + rebase wherein, your local commits are replayed and commit history is preserved.

git log shows a commit log of all changes along with their hashes.
git log --oneline is more useful as it is concise and easy to copy commit hashes from.

So you realize that a commit you made was a mistake, and it needs to be undone. After all, this is the benefit of using a version control system in the first place.
First do a git log --oneline and identify the commit you want to undo, and copy its commit hash.
Use git revert <commit hash id> to undo a specific commit. Remember that it made this change only to your local repo. If you want to propagate your change(undo) to the remote repo, you still need to do a git push.

Branch - What is? How to create a new branch? Switching to it? Merging with master? What happens when merging?
Conflicts - Example, how to resolve?
Stashing? What is ?
Cherry picking? What is?

GHPC wiki