Git Fundamentals

The model

Your files live in four places, and most commands move changes from one to the next:

• Working tree: the files you edit.
• Staging area (index): the changes you have chosen for the next commit.
• Local repository: the commits you have recorded.
• Remote: a shared copy of the repository, usually named origin.

Everyday commands

git clone <url>        # copy a remote repository, including its full history
git status             # what has changed, and what is staged
git add <file>         # stage changes (git add -p lets you pick parts of a file)
git commit -m "..."    # record the staged changes as a commit
git fetch              # download remote changes without applying them
git pull               # fetch, then merge into your current branch
git push               # upload your commits to the remote
git log --oneline      # history, one line per commit
git diff               # unstaged changes (git diff --staged shows staged ones)

Fetch versus pull

git fetch only updates your view of the remote (branches such as origin/main). Your own branches and files do not change, so it is always safe. git pull is a fetch followed by a merge (or a rebase, depending on your configuration), which changes your current branch.

Habits that keep you out of trouble

• Run git status before and after every operation until it becomes automatic.
• Pull before you start working and before you push, so you build on the latest state.
• Commit locally as often as you like; push when the work is ready to share.
• Read error messages. Git usually tells you what to do next.

Try it

Create a folder, run git init, add a file, and make two commits. Look at the result with git log --oneline. Then clone the repository to a second folder, make a commit there, and git pull it back into the first.