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Git Basics

In this section we will provide you a brief introduction to git as well as some materials for self study.

::: tip If you already have some experience using git you can jump immediately to resources section and start the Learn Git Branching exercise. :::

The basics

You are using git for the first time or coming back to it? Start here!

Settings for first timers

Git writes commit with your name and email address as metadata. Before you start doing anything with it let's setup the basics.

git config --global user.name "Alex Sample"
git config --global user.email "alex@sample.com"
git config --global core.editor "code --wait"
git config --list

Setting the core.editor tells git to use VSCode as your preferred editor for commit messages. Set this if you do not know vim or configure to your own preference.

The --list command shows you all currently active settings. They take into account your current projects settings, your global user settings and your system settings.

Creating the first repository

Now we are ready to go. Fire up a command line window and create a new folder. Then run the git init command inside that folder to enable the git version control for it.

$ mkdir getting-started && cd getting-started
$ git init
Initialized empty Git repository in /home/<username>/getting-started/.git/
$ git status
On branch master

No commits yet

nothing to commit (create/copy files and use "git add" to track)

The git status tells you what the current state of you git repository is. If there are current changes or even if you are in the middle of a complicated merge or rebase operation.

When in doubt run git status. It also gives you some instructions on what your next steps might be.

Let's create a new file and see if git notices the difference:

$ touch README.md
$ git status
On branch master

No commits yet

Untracked files:
  (use "git add <file>..." to include in what will be committed)
        README.md

nothing added to commit but untracked files present (use "git add" to track)

As you can see, git now noticed that there is a new untracked file inside you folder and suggests you to use the git add command to add it the tracking.

Let's follow the that recommendation.

$ git add .
$ git status
On branch master

No commits yet

Changes to be committed:
  (use "git rm --cached <file>..." to unstage)
        new file:   README.md

::: tip

The . in git add . tells git to track everything inside the current folder.

:::

Now git sees the new file and lists it under the Changes to be committed section.

Let's go ahead an create our first commit.

$ git commit -m "Create empty README.md"
[master (root-commit) 9c158cf] Create empty README.md
 1 file changed, 0 insertions(+), 0 deletions(-)
 create mode 100644 README.md

::: tip

If you omit the -m "Create empty README.md" from the above command, git will open your editor to enter the commit message. The commit command will wait for you to save and close the editor window.

:::

The de facto standard is to have a README.md markdown file on the root folder of your project to provide basic information and setup instruction for your project.

# Getting started with git

It's easy if you take one step at a time.
$ git status
On branch master
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
        modified:   README.md

no changes added to commit (use "git add" and/or "git commit -a")

$ git commit -a -m "Add a heading and some text"
[master 2985691] Add a heading and some text
 1 file changed, 3 insertions(+)

Let's extend our current README.md.

# Getting started with git

Git might look intimidating to begin with...

## How hard is it?

It's easy if you take one step at a time.

Also let's add a .gitignore file to ignore files that we don't want to track.

*.bak
*~

::: tip

Always use a .gitignore file in you projects. Since git tracks every file in the workspace by default you will almost always have files you want to ignore.

  • node_modules/ module dependencies that take a lot of space and can be installed using lifecycle management

  • tmp any kind of temporary files and build outputs

  • .vscode/ sometimes exclude editor-files and personal configuration

  • .secrets.env exclude files that may contain secrets

:::

Let's check the outputs of git status and inspect the changes to the files in more detail.

$ git status
On branch master
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
        modified:   README.md

Untracked files:
  (use "git add <file>..." to include in what will be committed)
        .gitignore

no changes added to commit (use "git add" and/or "git commit -a")

As you can see git noticed that we have changed the README.md and have a new file named .gitignore in our current working directory.

Let's check in detail what changes it detects on the README.md.

git diff

You should see some output like this:

diff --git a/README.md b/README.md
index cebce42..456c986 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,7 @@
 # Getting started with git

+Git might look intimidating to begin with...
+
+## How hard is it?
+
 It's easy if you take one step at a time.
(END)

:::tip You can close the diff viewer by pressing Q. :::

Note that git inserted the new lines between the first ones and remember the initial lines stay the same.

The .gitignore files is not shown here. Changes to it are not tracked yet.

$ git commit -am "Add more content to README and ignore temporary files"
[master 0a92cb8] Add more content to README and ignore temporary files
 1 file changed, 4 insertions(+)

Now you have created your first commits let's see how we can share them with your colleagues.

First create a new repository on GitHub:

new repository

Then you can follow the instructions for connecting your local repository.

Helpful resources

If you feel underwhelmed with the content of this intro, check out Learn Git Branching and see if you can master the later levels of the tutorial. You should already know you way around git to get the most out of it.

How to create a sample tree

This is an optional task to create a sample object graph in git and later exploring it using the git cat-file command.

$ mkdir git-basics
$ cd git-basics
$ git init
Initialized empty Git repository in /home/<username>/git-basics/.git/

$ echo "version 1" > test.txt
$ git add test.txt
$ git commit -m "first commit"
[master (root-commit) fdf4fc] first commit
 1 file changed, 1 insertion(+)
 create mode 100644 test.txt

$ echo "new file" > new.txt
$ echo "version 2" > test.txt
$ git add new.txt test.txt
$ git commit -m "second commit"
[master cac0ca] second commit
 Date: Thu Apr 8 11:50:56 2021 +0200
 2 files changed, 2 insertions(+), 1 deletion(-)
 create mode 100644 new.txt
$ git branch test

$ mkdir bak
$ echo "version 1" > bak/test.txt
$ git commit -m "third commit"
[master 1a410e] third commit
 1 file changed, 1 insertion(+)
 create mode 100644 bak/test.txt

refs-tree

Now you can start browsing the tree structure like this:

$ git cat-file -p master
tree 3c4e9cd789d88d8d89c1073707c3585e41b0e614
parent 324177edbf6d0ae3f12d657302f2627d6347c2c6
author Clemens Wältken <clemens.waltken@microsoft.com> 1617876347 +0200
committer Clemens Wältken <clemens.waltken@microsoft.com> 1617876347 +0200

third commit
$ git cat-file -p 3c4e9c
...