11 Painful Git Interview Questions You Will Cry On

• A fork is a remote, server-side copy of a repository, distinct from the original. A fork isn't a Git concept really, it's more a political/social idea.
• A clone is not a fork; a clone is a local copy of some remote repository. When you clone, you are actually copying the entire source repository, including all the history and branches.
• A branch is a mechanism to handle the changes within a single repository in order to eventually merge them with the rest of code. A branch is something that is within a repository. Conceptually, it represents a thread of development.

In the simplest terms, git pull does a git fetch followed by a git merge.

• When you use pull, Git tries to automatically do your work for you. It is context sensitive, so Git will merge any pulled commits into the branch you are currently working in. pull automatically merges the commits without letting you review them first. If you don’t closely manage your branches, you may run into frequent conflicts.

• When you fetch, Git gathers any commits from the target branch that do not exist in your current branch and stores them in your local repository. However, it does not merge them with your current branch. This is particularly useful if you need to keep your repository up to date, but are working on something that might break if you update your files. To integrate the commits into your master branch, you use merge.

• A branch is just a separate version of the code.

• A pull request is when someone take the repository, makes their own branch, does some changes, then tries to merge that branch in (put their changes in the other person's code repository).

Gitflow workflow employs two parallel long-running branches to record the history of the project, master and develop:

• Master - is always ready to be released on LIVE, with everything fully tested and approved (production-ready).
• Hotfix - Maintenance or “hotfix” branches are used to quickly patch production releases. Hotfix branches are a lot like release branches and feature branches except they're based on master instead of develop.

• Develop - is the branch to which all feature branches are merged and where all tests are performed. Only when everything’s been thoroughly checked and fixed it can be merged to the master.
• Feature - Each new feature should reside in its own branch, which can be pushed to the develop branch as their parent one.

The Forking Workflow is fundamentally different than other popular Git workflows. Instead of using a single server-side repository to act as the “central” codebase, it gives every developer their own server-side repository. The Forking Workflow is most often seen in public open source projects.

The main advantage of the Forking Workflow is that contributions can be integrated without the need for everybody to push to a single central repository that leads to a clean project history. Developers push to their own server-side repositories, and only the project maintainer can push to the official repository.

When developers are ready to publish a local commit, they push the commit to their own public repository—not the official one. Then, they file a pull request with the main repository, which lets the project maintainer know that an update is ready to be integrated.

Say you have this, where C is your HEAD and (F) is the state of your files.

   (F)
A-B-C
    ↑
  master

1. To nuke changes in the commit:

git reset --hard HEAD~1

Now B is the HEAD. Because you used --hard, your files are reset to their state at commit B. 2. To undo the commit but keep your changes:

git reset HEAD~1

Now we tell Git to move the HEAD pointer back one commit (B) and leave the files as they are and git status shows the changes you had checked into C. 3. To undo your commit but leave your files and your index

git reset --soft HEAD~1

When you do git status, you'll see that the same files are in the index as before.

• The working tree/working directory/workspace is the directory tree of (source) files that you see and edit.
• The index/staging area is a single, large, binary file in /.git/index, which lists all files in the current branch, their sha1 checksums, time stamps and the file name - it is not another directory with a copy of files in it.
• HEAD is a reference to the last commit in the currently checked-out branch.

The command git cherry-pick is typically used to introduce particular commits from one branch within a repository onto a different branch. A common use is to forward- or back-port commits from a maintenance branch to a development branch.

This is in contrast with other ways such as merge and rebase which normally apply many commits onto another branch.

Consider:

git cherry-pick <commit-hash>

The git stash command takes your uncommitted changes (both staged and unstaged), saves them away for later use, and then reverts them from your working copy.

Consider:

$ git status
On branch master
Changes to be committed:
new file: style.css
Changes not staged for commit:
modified: index.html
$ git stash
Saved working directory and index state WIP on master: 5002d47 our new homepage
HEAD is now at 5002d47 our new homepage
$ git status
On branch master
nothing to commit, working tree clean

The one place we could use stashing is if we discover we forgot something in our last commit and have already started working on the next one in the same branch:

# Assume the latest commit was already done
# start working on the next patch, and discovered I was missing something

# stash away the current mess I made
$ git stash save

# some changes in the working dir

# and now add them to the last commit:
$ git add -u
$ git commit --ammend

# back to work!
$ git stash pop