Git Basics

How to git good

The basics

(I will be generalising so don't worry about full technicalities)

The very basic local/remote structure

• GitHub (plus GitLab, BitBucket and others) host remote repositories.
• You can "copy" (clone) a remote repository, which sets it as a remote for your local repo.
• Locally, you actually have two repositories:
  • Your local working repository
  • Your local copy of the remote repository (this is called origin)
• git pull first runs git fetch origin/<branchname> to get changes from the remote, then runs git merge origin/<branchname> to merge remote changes into your local working repository
• Locally, there are 5 different states that files can be in:
  • Committed
    • This is when all changes to a file are part of a commit
  • Staged
    • This is when a file has been added to "the staging area". Basically, you have run git add and are signalling the file is ready to commit
  • Unstaged
    • The state of a file you are working on that has previously been committed
  • Untracked
    • Basically a new file that hasn't been added to git yet
  • Ignored
    • A file that there is specific rule in the .gitignore file for, and will not be picked up by git

Commands

There are some basic commands you need to know:

• git config
  • Generally you use this command once at the start of installing git, when you do the following:
    • git config --global user.name "My Name"
    • git config --global user.email "my@email.com"
• git init
  • This is useful for initialising local git repos, however, it's usually easier to make a remote repo in github and clone it
• git clone <repo link>
  • This is used to copy a remote repository down to your device
  • For https: [https://github.com/<your username>/<your repo name>.git]
  • For ssh (not for beginners): [git@github.com:<your username>/<your repo name>]
• git status
  • This command is used to see what the state of your local repository looks like
  • This will show committed, staged, and unstaged files, as well as new files
• git add <file path>
  • This command is often used with a . in the place of the file path, which just adds all files in the current folder into staging
  • You can used this command to specifically ignore some files when committing by only adding some files to your commit
• git commit
  • By default, this will open up your editor of choice (ie. nano, vim, VSCode) and ask you to enter a commit message and save the file
  • You can also add flags to this command, which can be chained (ie. git commit -am "Initial Commit")
    • -a will stage all unstaged files
    • -m will allow you to write a message inline with the command
• git push
  • This will allow you to push your committed changes up to your remote repository
  • If you're working off a new local branch, use push -u origin <branch name> to setup a branch in your remote repository and push to that
• git pull
  • This will fetch down changes from your remote repository into your local copy of the remote, and then merge that into your working repository
• git fetch
  • This will fetch down any changes into your local copy of the remote repo (origin)
  • Useful for checking out if any changes on your local main/master conflict with the remote if others have been working on it
• git merge
  • This allows you to merge changes from one branch into another
  • Useful when changes have been made to master and you want to bring your branch up to date
• git branch
  • Basically just lists all your branches. Use -a to show remote branches too
  • Use -D <branchname> to delete a local branch that has not been merged in the remote, and -d <branchname> to delete a local branch that has been merged in the remote
• git checkout
  • Use this to both switch between branches and to make new branches
    • git checkout <branchname> to move to that branch
    • git checkout -b <new branchname> to create a branch and automatically switch to it
• git log
  • This command will show you all the past commits for you branch
• git stash
  • This will "stash" all your changes in the current repo, and remove them from current state. Useful if you want to save unfinished work and switch branches
  • The stash is saved as a stack following the Last-In-First-Out principle
  • You can view specific stash items by git stash show@{<index of stash item>}
• git stash list
  • This will list stash items
• git stash apply
  • This will add the top changes from the stash back to the working directory, without removing them from the stash
  • You can specify a stash item to apply (ie. git stash apply stash@{1})
• git stash pop
  • This will apply stashed changes, and remove those changes from the stash
  • Again, you can do this for specific positions with git stash pop stash@{<stash index>}
• git reset
  • Dangerous: this will reset back past commits and can be potentially destructive
  • You can use several options, but the most common are:
    • --soft to keep all the changes in the commits you're resetting past
    • --hard to hard wipe back to the commit you're resetting to
  • Usage: git reset <commit to reset to>
    • This can be a specific commit hash
    • Or you can use HEAD^ to revert your latest commit
    • Or you can use HEAD~<number of commits to rollback> to go a certain number of commits backward
• git remote
  • Use git remote -v to list all your remotes
  • This will be covered more in the Fork-and-Pull section