Branching in Git – Everything You'll Need to Know About Git

Git Branching

You don't always want to be developing on the main branch. Sometimes you need a feature that is developed off the main line, such that you can return to the main line, update the code, branch off, and perform some immediate needed fix.

This is where git branches come in. They are cheap, virtually free, to create. With our of understanding git internals this will become much more clear throughout this section

Problem

Since we are in a new git repo, lets create our initial commit. We will be using the hello-git you just created previously to test the trunk default branch setting

I would like a README.md with one line, A, and a commit message of A

Solution

➜  hello-git git:(trunk) echo "A" > README.md
➜  hello-git git:(trunk) git add .
➜  hello-git git:(trunk) git commit -m 'A'

[trunk (root-commit) cb75afe] A
 1 file changed, 1 insertion(+)
 create mode 100644 README.md

Creating branches

Creating branches is easy

git branch foo

Will create a new branch named foo

Problem

Try it out, create a branch named foo

Solution

➜  hello-git git:(trunk) git branch foo
➜  hello-git git:(trunk)

Well... what happened?

A branch was created pointing to the same commit as trunk
We remain on trunk

List out branches

We can observe this by executing git branch. git branch will display all of our local branches

git branch

Problem

List out your branches. How do you know what branch you are on? Use git log with --decorate to see where the branches point at and prove that foo points to the same commit as trunk

Side Note If you use git log and you see the same output as when you use --decorate this happens. There are some internal settings that automagically make this happen

git log > out
cat out

you may notice that you lose the branching information that you had.

Solution

git branch

  foo
* trunk
(END)

That shows we have 2 branches, one foo and one trunk. trunk is selected, and you can tell because of the *

lets execute git log and write down our sha for this specific commit

commit cb75afebfac407bfc860dd854b626322a6dc8345 (HEAD -> trunk, foo)
Author: ThePrimeagen <the.primeagen@gmail.com>
Date:   Sun Jan 28 10:04:01 2024 -0700

You will notice that the commit has HEAD -> trunk, foo. foo is pointing to this commit. A branch POINTS to a commit, it is not a set of changes.

A Touch of Git Foo

Can you find your branch details in .git?

Ahh yes... its right there...

➜  hello-git git:(trunk) cat .git/refs/heads/foo
cb75afebfac407bfc860dd854b626322a6dc8345
➜  hello-git git:(trunk) cat .git/refs/heads/trunk
cb75afebfac407bfc860dd854b626322a6dc8345

Switching branches

You can switch branches easily in two ways

git switch <branch name>
git checkout <branch name>

checkout is a more versatile operation and i am personally just in the habbit of using it. You can use whatever you want / are comfortable with

Problem

switch to branch foo

Solution

➜  hello-git git:(trunk) git checkout foo
Switched to branch 'foo'

Problem

Now that you are foo lets create another commit with message B and a new line added to second.md of "B"

Then do it again, except replace B with C

When finished use git log with what options you want, to see if you can see some differences now!

This should be the setup you should have at the end of this

    B - C foo
   /
  A       trunk

Solution

➜  hello-git git:(foo) echo "B" > second.md
➜  hello-git git:(foo) git add .
➜  hello-git git:(foo) git commit -m 'B'

[foo 4ad6ccf] B
 1 file changed, 1 insertion(+)
 create mode 100644 second.md

➜  hello-git git:(foo) echo "C" > second.md
➜  hello-git git:(foo) git add .
➜  hello-git git:(foo) git commit -m 'C'

[foo 16984cb] C
 1 file changed, 1 insertion(+), 1 deletion(-)

Now lets execute git log and see if we can see a difference

commit 16984cb1725b0bfeff43f60f92b3467ee6d525e3 (HEAD -> foo)
Author: ThePrimeagen <the.primeagen@gmail.com>
Date:   Sun Jan 28 10:17:11 2024 -0700

    C

commit 4ad6ccf530547ce89cfd90cd7a6e747f9531d917
Author: ThePrimeagen <the.primeagen@gmail.com>
Date:   Sun Jan 28 10:15:38 2024 -0700

    B

commit cb75afebfac407bfc860dd854b626322a6dc8345 (trunk)
Author: ThePrimeagen <the.primeagen@gmail.com>
Date:   Sun Jan 28 10:04:01 2024 -0700

    A

2 things:

Notice that HEAD -> foo, or current location of git points to foo, which is 16984cb
trunk is still at A. Trunk has not been updated with this code

Fun side-note

try out --graph if you didn't!
try out --oneline if you haven't
try all three options together!

You can delete branches

If you create a branch and you wish to delete it you can use -d and -D. For more information read up in the git manual, man git-branch

Commits locked in...

Ok, now that we have a branch full of changes... what do we do with it?

← Previous Next →