DEV Community

Cover image for Confused by git?  Here's a git crash course to fix that πŸŽ‰
Chris Achard
Chris Achard

Posted on • Originally published at twitter.com

Confused by git? Here's a git crash course to fix that πŸŽ‰

This was originally posted as a twitter thread: https://twitter.com/chrisachard/status/1171124289128554498

NOTE: if you are looking for a very basic intro to git, I recommend reading this guide by Atlassian first.

Do you use git but still don't really understand it?

Here's a πŸ”₯ git crash course πŸ”₯ to fix that πŸŽ‰

1.

Git gives you a FULLY FEATURED repository on your local computer

This is different than other version control systems

Once you embrace that, you can start demystifying some of the git 'magic'

Decentralized repos

2.

Think of files (and changes) as being in 5 different places, or "states"

  • Working directory
  • Staging (Index)
  • Commit tree (local repo or HEAD)
  • Stash
  • Remote repo (github, Bitbucket, gitlab, etc)

Files move between 5 states

3.

Think of moving files (or changes) between those places:

git add working dir => staging

git commit staging => HEAD

git push HEAD => remote repo

git stash working dir <=> stash

git reset and git checkout to pull from upstream

Commands that move files between states

4.

Why have a dedicated staging area?

So that you can choose and review which files and changes to commit before committing.

Dedicated staging area

5.

git status shows changes in both your working directory and staging, but think of them as separate things.

git log shows the history of commits your local repository

git status and git log

6.

Learn to love git log

It's a snapshot of repo state: shows past commits as well as local HEAD, local branch, remote HEAD and remote branch

git log --oneline is compact way to view commit history

git log

7.

A branch is a reference to the tip of a line of commits

It automatically updates when new commits are added to that line

Making a new branch will diverge the tree at that point

branching

8.

A merge takes two branches and makes a NEW commit which combines them

If there are conflicts, you have to manually resolve them (no shortcuts!)

Merge

9.

git rebase lets you rewrite commit history

Applies your current commits directly to branch HEAD

Can squash all your commits into one to clean up history

Don't do this to public (remote) commits!

Rebase

10.

Some people say you should only ever merge to keep your entire history

Some people say you should always rebase before merging into master to keep a clean history tree

I say: do whatever works for you and your team πŸ€·β€β™‚οΈ

11.

HEAD can point to a branch or a specific commit

If it points to an old commit, that's called a "detached HEAD"

Editing in a detached HEAD state is dangerous (can lose work or cause problems combining work)

HEAD

12.

Many git commands can operate on either: individual files, commits, or branches

This can cause a lot of confusion - so make sure you know what TYPE of object you're operating on

13.

There are many ways to undo unwanted actions in git
Here are the most common:

unstage a file: git reset [file]

change last LOCAL commit: git commit --amend

undo local commit: git reset [commit BEFORE the one to undo]

undo remote commit: git revert [commit to undo]

14.

There's SO MUCH MORE I could have talked about!

What other things confuse you about git?

Comment below and I'll try to answer or find some resources for you πŸ™Œ

Β 

Like this crash course?

Follow me on twitter for more: @chrisachard

Or you can join the newsletter: https://chrisachard.com/newsletter

Thanks for reading!

Latest comments (38)

Collapse
 
achargoy profile image
Chargoy

Thank you so much for this course, really amazing πŸ‘.

Collapse
 
arif98741 profile image
Ariful Islam

Pretty good and clear article no doubt. Those who always fail to memorize basic git commands, I make a datatable which name is gitcom. you can check from below link as well.
arif98741.github.io/gitcom/

Collapse
 
evolutionxbox profile image
Jonathan Cousins

The biggest misconception I find (which I couldn’t see listed here) is that a the history is a list of changes. Instead commits are snapshots of the entire repo, not just changes.

Collapse
 
chrisachard profile image
Chris Achard

That's a good point - git is unlike SVN in that way. SVN stores diffs (which is why it can take a long time to calculate the current state when your repo history gets really long), and git stores entire files. I always had thought that git stored diffs as well (since you "commit" just the change, right?) - but nope!

I didn't include it because I find that, in practice, it doesn't matter much whether you think of the commit log as being diffs or snapshots - but I could be wrong... have you found cases where it matters a lot which way you think of it? Thanks!

Collapse
 
evolutionxbox profile image
Jonathan Cousins

It does when people get comfortable with cherry picking.

Thread Thread
 
chrisachard profile image
Chris Achard

Ah, good point

Thread Thread
 
evolutionxbox profile image
Jonathan Cousins

You have a very helpful article. I would definitely not expect someone new to git to start cherry picking.

Thread Thread
 
chrisachard profile image
Chris Achard

Thanks! Yeah; maybe on a more advanced course sometime :)

Collapse
 
ogaston profile image
Omar Gaston Chalas

wow! git log --oneline is amazing

Collapse
 
kaxi1993 profile image
Lasha Kakhidze

The major git features, explained so simply, thanks Chris!

Collapse
 
camblan profile image
Julien Camblan

The clearest git cheatseet, thank you! πŸ™

Collapse
 
alpe89 profile image
Alberto Pertusi

Very good explanation, thanks :)

Collapse
 
nutriz profile image
JΓ©rΓ΄me Gully • Edited

Best git summary ! Clear, concise, simple illustrations. I already master all these commands, but I never seen a so summary, so thanks. I will spread my team with your post :)

Collapse
 
m_starca profile image
marko

What is command when changes should be added under pushed commit?

Collapse
 
chrisachard profile image
Chris Achard

If I understand correctly, what you want is to add the extra files to the staging area with:

$ git add FILE

and then you can add them to the most recent commit with

$ git commit --amend

Does that solve the issue?

Collapse
 
m_starca profile image
marko

Is this also working for remote last commit?
Thank you.

Thread Thread
 
chrisachard profile image
Chris Achard

If you want to change a remote commit, you'll have to do this, and then push with -f (which is a force push).

HOWEVER! Be careful with force push. If you accidentally force push to the wrong branch, then it can really mess you up, and if you have teammates who have already downloaded a public branch (like master), then force pushing to master isn't a good idea.

If you've already pushed to a public branch, the better choice is probably to just make a new commit.

Thread Thread
 
m_starca profile image
marko

I will keep that in mind. Thank you.

Collapse
 
tripol profile image
Ekanem

First time hearing about git log --oneline. A truly cleaner way to look at the history.

Thanks Chris

Collapse
 
nutriz profile image
JΓ©rΓ΄me Gully

And there is much more... try
git log --all --decorate --oneline --graph :)

Collapse
 
tripol profile image
Ekanem

Just did it! Thanks.

Now I feel like a 10x developer :)

Collapse
 
chrisachard profile image
Chris Achard

Yes! there's a whole bunch :) Here's the full docs if you're interested: git-scm.com/docs/git-log (examples at the bottom)

Collapse
 
chrisachard profile image
Chris Achard

Glad it helped!

Collapse
 
papidev profile image
Papidev

Love it, so clear

Collapse
 
jameesy profile image
Jamees Bedford

On fire with these recent posts Chris!! πŸ”₯

Collapse
 
chrisachard profile image
Chris Achard

Thanks!

Collapse
 
khangprcvn profile image
khangprcvn

Wow, thank you.

Collapse
 
alexfrompalmsprings profile image
AlexCodes

Thank you!! I am currently learning git

Collapse
 
chrisachard profile image
Chris Achard

Glad it helped!

Some comments may only be visible to logged-in visitors. Sign in to view all comments.