Creating a Branch

Creating a Git repository#

You will create a Git repository with a single file. This file will have separate changes made on two branches: master and newfeature.

Type the following command to create a simple Git repository:

1   mkdir lgthw_git_branch_1
2   cd lgthw_git_branch_1
3   git init
4   echo newfile > file1
5   git add file1
6   git commit -m 'new file1'
7   git status

The git branch command#

To create a new branch, type the following commands:

8   git branch newfeature
9   git status
10  git branch

Now you have created a branch called newfeature.

What branch are you on now? Was that what you expected?

Add a commit on the master branch:

11  echo Line_master1 >> file1
12  git commit -am 'master change'

Type the following command. See if you can work out the difference between them:

13  git log --decorate --graph --oneline

The attentive learners will have noticed that I slipped in a new flag. The --decorate flag gives you useful information about the reference names (branches and tags) at various commit points. This is so handy. Adding it to git log is part of my muscle memory now.

Is --decorate the default?
In recent versions of Git, it is the default to show --decorate if Git is writing to a terminal even if it’s not supplied. If you output the git log command to a screen and redirect it to a file with the > operator, you might see a difference in content.

Type this in and think about what’s going on:

14  git checkout newfeature
15  cat file1
16  echo Line_feature1 >> file1
17  git commit -am 'feature change'
18  git log --decorate --graph --oneline --all

Another flag (--all) was added there. As you’ve probably worked out, --all shows all branches, not just the branch you happen to be on.

This is also in my muscle memory, but sometimes it produces insane graphs I can’t read, so I have to remember to remove it now and again.

Back to the code. You have added a feature (i.e., a code change) to the newfeature branch. Go back to the master branch and check that the file1 doesn’t have the changes you made on the newfeature branch:

19  git checkout master
20  cat file1

Branch diagram#

This diagram shows the final state of the commit tree:

This reflects the output of the last git log command. But note that it has a different orientation to the git log command. In the diagram, the commits are shown left-right in time order, while git log shows them from top to bottom.

Take a moment to be sure you’ve understood that difference in representation.

Differently-oriented and confusing Git diagrams are the norm in the Git world, and you will come across this challenge again later.

Note that the HEAD (and branch) moves forward with each commit.

The HEAD is where Git is pointed at right now in your repository, and the branch is where that branch reference is pointed to.