Use Git

Basics

Commands you will probably learn out of habit

• git pull origin <branch> to get the latest version of a branch.
• git fetch if you don't have the latest branches.
• git checkout <branch> to switch to a branch.
• git checkout -t origin/haml -- checks out the haml branch from the remote repo known as origin. The -t flag is short for --track, which allows you to simply use git push and git pull without specifying the remote and remote-branch.
• git add <file> if you've created a new file or if you want to explicitly choose which files to commit.
• git commit -am "<message>" to commit your changes. Leave out the a if you chose specific files with git add.
• git push origin <branch> so the rest of us can see your changes.

Creating a branch

When working on something, you should be on your own branch. When beginning a project, simply do git checkout -b <branch_name>. Push all of your changes there.

Read more about branching.

Viewing logs

git log --abbrev-commit --pretty=oneline
git log --abbrev-commit --pretty=oneline --graph

Alternatively, just alias git log --graph --abbrev-commit --decorate --oneline --date=relative --all to an abbreviation you'll remember.

The Three States

Read about the various states a file can be in here.

Generally, you create a "untracked" new files (touch file.txt). To "stage" a file, you do a git add file.txt. When you're ready to commit everything you've changed, do git commit -am "message". The -a switch stands for --all and tells the command to automatically stage files that have been modified and deleted (but new files you haven't told Git about are not affected).

Switching Branches without Committing

Say you're on a feature-A, did some work, don't want to commit that work yet, and also you want to switch to feature-B. You can stash your changes and recover them at a later time.

git stash
git checkout feature-B
git checkout feature-A
git stash list # list files stashed
git stash show # inspect files stashed
git stash apply # recover stashed changes

apply will keep the stash changes on top of the stash stack. Overall, you can pop, drop, or apply.

Fixing that last commit message I screwed up

To amend the last commit message, git commit --amend. If you want to amend the commit message that occurred 10 commits ago, use git rebase -i HEAD~10. This will open up interactive git-rebase, which will allow you to (among other things) amend the last 10 log messages.

Viewing Diffs

To see the diff between the last commit and the current working directory, use git diff.

To see only staged changes, use git diff --cached.

Rebasing is a life-saver

Scenario

Bob is working on his feature branch. Alice pulls her feature branch into master. Bob's feature is now several commits behind master.

                     A---B---C topic
                    /
               D---E---F---G master

Solution

What does Bob do?

git checkout master
git pull
git checkout bob-feature
git rebase master

And voila...

                             A'--B'--C' topic
                            /
               D---E---F---G master