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Figuring where you at

Looking at changes

  • git diff - the diff since last commit
  • git diff SOMESHA - the diff since SOMESHA
  • git diff BRANCH-NAME - the diff from another branch
  • git show - show the diff of last commit
  • git show SOMESHA - show the diff of SOMESHA

Staging changes

Use git add

  • git add -A/git add ./git add -a
    • Don't use these. (except maybe your first commit)
  • git add FILENAME_OR_DIR, this is better
  • git add -p
    • stages in hunks
    • allows you to see each line of diff while deciding what to include
  • git reset to un-stage your changes

Committing changes

If you have staged your changed properly all you need is

  • git commit
    • ex git commit -m 'add person.js'
    • use present tense for your messages
  • git commit --amend to add to previous commit
    • Use this if you forgot to add something to your last commit
    • If you have pushed before doing this, you will need force-push


  • git fetch - don't use this
    • gets the changes of a branch/branches
  • git pull - use this
    • gets the changes and updates your branches accordingly


Use git push

  • git push origin BRANCH-NAME
  • git pushf origin BRANCH-NAME
    • add the alias pushf = push --force-with-lease to .gitconfig if you don't have it
    • Never pushf if you don't need to
    • Always make sure you know what you are overriding! git diff origin/BRANCH-NAME

Debugging history

One of the many great things about git is it makes diagnosing issues easy.

Check these out !!

  • git blame
    • git blame FILENAME - see history of file chages
    • add alias praise = blame for positivity!
  • git bisect
    • This is effectively a binary search to find a commit that broke something

Checking out branches

Use git checkout

  • git checkout BRANCH-NAME
  • git checkout - go back to last branch
  • git co is a common alias

Merging and rebasing branches


git merge

Typically branches, should be merged into master. This should be done from Github. Merging takes every commit and along with a merge-commit from the branch and adds that to the target branch (usually master)

Ex: From master: git merge BRANCH-NAME takes all the commits from BRANCH-NAME and a merge-commit and adds those to master.


git rebase

Rebasing rewrites history. This adds the commits from another branch and puts your commits on top of your branch. (Actually it puts new copies of your commits on top). Typically, we rebase master from another branch. This does not add an extra merge-commit.

Ex: From some branch: git rebase master will take anything that was added to master since branched off (or last rebased) and put those commits before yours. Your commits are then added on top of your branch.

Adding a feature

  • Do NOT commit directly to master
  • Check out a branch from master git checkout my-new-feature
    • where my-new-feature is the branch name
  • Add your code and commit git commit -m 'add my new feature'
  • Push your branch to GitHub git push origin my-new-feature
  • Make a PR on GitHub
  • Review the changes
  • Make requested updates, commit again
  • Merge PR into master from github

If there are conflicts

  • From the new branch, git rebase master
  • You will see an error like CONFLICT (content): Merge conflict in FILENAME
  • Manually resolve the conflicts. Use your human mind.
    • Git cannot tell you what to do here. Figure out what changed since you branched off of master
    • What is the goal of your changes? Why did they touch the same or adjacent lines?
  • Once the conflicts are resolved:
    • git add FILENAME, git rebase --continue
  • If there are more conflicts, you must resolve those too
  • Finally you can push the rebased branch back up to github git pushf origin my-new-feature
    • You will have to force-push since you are re-writing history
  • Now you should be able to merge from github
  • If you mess up the rebase along the way you can always git rebase --abort and start over

Things to remember

To make sure you don't lose your work always keep these things in mind

  • Commit often - keep your commits small
  • Push often - once every few commits
  • Look at the diff from origin before force-pushing
  • Do not push to master. Make a PR
  • Look at the docs. Do not just copy-paste from Stack Overflow without knowing what it does