Best Practices: Git and GitHub

• Datree.io: Top 10 GitHub best practices for developers
• GitHub Resources: GitHub best practices
• Pandeiro: Git Best Practices

Git Basics and Commands

• SHA: The 40 digit hash number that verifies data integrity for a commit
  
• HEAD: A pointer; always points to tip of currently checked out branch
  
• Git commands are prefaced with the word git: git add, git delete, git diff, etc.

Global Configurations

From any place in the command line, type

git config --global user.name "daisytrench"
git config --global user.email "catherine.snider@colorado.edu"
git config --global color.ui tru # color the user interface
git config --list # will display the config that you have already set

Remote repository

git branch -r # shows remote branches
git remote show origin # shows the remote repository URL, branches and other info
git fetch # pulls changes from the origin-master branch
git pull # does a git fetch followed by a git merge
git push # pushes committed changed up to remote
git push --set-upstream origin {branchName} # creates remote branch and pushes to it
git remote remove origin # disconnects from origin so you can do your Drupal lessons w/o messing up Express

Branches

A new branch is created off of the current branch.

git branch # shows branches; highlights the currently checked out branch
git checkout <branchname> # switches HEAD to an existing branch
git checkout -b <branchname> # creates a new branch and switches HEAD to it at the same time
git branch -a # shows local and remote branches
git branch -d branchNameHere # deletes named branch if it's been merged
git branch -D branchNameHere # deletes named branch even if not merged
git branch --merged # shows the branches that have been merged
git branch --no-merge # shows branches that haven't been merged

Merging Branches

Be on the receiver branch, i.e. the one into which you are merging. You pull in the changes from the other branch. Then merge:
git merge <branch-to-merge>

Branch Stats

git status # reports the difference between the working directory, the staging index and the repository
git log # shows all commits with SHAs and commit message, latest to earliest
git log -n 3 # show me the last three commits
git log --oneline # easier to read
git log --since=2015-01-01 # everything since given date

Differences

git diff show file differences that haven’t been staged git difftool open the specified tool to view diffs

Staging and Committing

Add changed files to staging area:
git add .
git add <filename>

Commit Messages

How to Write Useful Commit Messages

The template:

Summarize the change in less than 50 characters

Because:
- Explain the reasons you made this change
- Make a new bullet for each reason
- Each line should be under 72 characters

Explain exactly what was done in this commit with more depth than the
50 character subject line. Remember to wrap at 72 characters!

git commit -m "Explanatory Message"
As the project drags on

Undoing Mess-ups

git reset <last good SHA> # specifies where the head pointer should point. Very powerful and can undo a bunch of work that maybe you didn't mean to.
* --soft # leaves staging and working in their later revised state; you'll need to do a merge. The git repository will be reset to an earlier version. Do a Git Diff to see the difference.
* --mixed # default; moves head to earlier commit; changes staging index to match repository; does not change working directory. We have not lost any work. Do a Git Diff to see the difference.
* --hard # destructive; moves pointer of repository; makes staging and working directory match repository. You'll lose all work since the last commit. Sometimes you want that.
* --hard origin/master # nuke this thing: throw away all my staged and unstaged changes, forget everything on my current local branch and make it exactly the same as origin/master

Working with Repositories

Create a New Local Repository

Two ways: by cloning someone else’s work or using your own.

1. Cloning an existing GitHub repository:
   
   • Get the clone URL from GitHub
     
   • From command line, in parent directory:
     git clone {repositoryURL}
     The new directory is automatically initialized as a git repo and is connected to the remote origin
     
2. Using your own work:
   
   1. Initialize the project directory as a Git Repository
      In root of directory you want to start tracking:
      git init
echo "# MyRepoName" >> README.md
touch .gitignore (create empty .gitignore file in root of project directory)
      Add any binary files to the .gitignore file
      echo "/images/*" >> .gitignore
      Several .gitignore recipes are available for Drupal 7: CU-Boulder’s or jbudziak’s for example.
      Screw up the GitIgnore at your peril.
   2. Add files to staging area
      git add .
      Review the list. Remove any binary files from the staging area and add them to .gitignore
      git reset HEAD {filename} (removes the one) or git reset HEAD . (just start over)
   3. Commit everything to the respository git commit -m 'initiating repository
   4. Connect new local repo to a remote repo on GitHub
      The repository must exist on GitHub
      Go to GitHub and create the repository; copy its URL
      git remote add origin {repositoryURL}
git push -u origin master

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