Quick guide to Git in 12 Steps

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Many times I have encountered the need to initiate a person on using git. There are many documentations online but many of them are quite extensive described so I will try to make a shorter version for beginners.
I will use Github as a remote server and a real repository as the example.

Short legend:

  • Branch – it represents a line of development. Thing of it as an isolated room. You will start from a main room (master) and when you will create a new branch your room will be a clone of the room from where you create the new room: your new room will contain all content from master room at that point
  • Commit – it represents a recorded change. Thing of it as a box. You work in a room, you create different things, you put your current work (track changes) in a box that you label it (the commit message).

If you want to have a remote server know your room (branch) content you will have to push the changes.
If you want content from another room you merge with it.

So let’s try to do a Quick Guide by example:

1. Create the repository reference on Github (after creating an account, off course):

Access https://github.com/new, fill out the form and press Create repository (I will use “image” as the repository name)

2. Create a new local directory and init the repository

mkdir image
cd image
git init

3. Create a file

touch README.md

4. Tracking your file

git add README.md

5. Committing your tracked changes

git commit -m "Initial release"

6. Upload your modification on github

git push -u origin master

Note: -u parameter is necessary just on the first branch push so it can set-up stream (associate your branch with the remote one)

7. View status (changes between the last commit and your modifications):

# create a new file and a content
touch my_new_file && echo "my content" > my_new_file
echo "Readme content" > README.md 
git status
# On branch master
# Changes not staged for commit:
# (use "git add <file>..." to update what will be committed)
# (use "git checkout -- <file>..." to discard changes in working directory)
#
# modified: README.md
#
# Untracked files:
# (use "git add <file>..." to include in what will be committed)
#
# my_new_file

8. Canceling modification done to a file (reset to the last commit state)

git checkout README.md

Note: You can reset all your modification using git checkout .

9. Create a new branch

git checkout -b MY-NEW-BRANCH

10. Reset tracked changes

We will make some changes first so we can have something to reset.:

echo "Readme content\nNew content" > README.md
git add .
# On branch MY-NEW-BRANCH
# Changes to be committed:
#   (use "git reset HEAD ..." to unstage)
#
#       modified:   README.md
#       new file:   my_new_file
#

Now the resetting step:

git reset README.md
# On branch MY-NEW-BRANCH
# Changes to be committed:
#   (use "git reset HEAD ..." to unstage)
#
#       new file:   my_new_file
#
# Changes not staged for commit:
#   (use "git add ..." to update what will be committed)
#   (use "git checkout -- ..." to discard changes in working directory)
#
#       modified:   README.md
#

Note To reset all tracked modifications, use git reset with no file parameter

12. View logs

First let’s create modification in MY-NEW-BRANCH

git add README.md my_new_file
git commit -m "Add some difference"

The actual view logs:

git log
commit 4d2b83a8946be59cb9924c46c7513d7a2cb07595
Author: Adrian Tilita 
Date:   Fri Jan 27 15:52:18 2017 +0200

    Add some differences

commit ee621d6abd302a0c7d1884d0cc4d43d5d828c083
Author: Adrian Tilita 
Date:   Thu Jan 26 13:39:55 2017 +0200

    Initial release

Note Use git log --oneline to view just the commit hashes and messages

12. View difference between 2 branches/commits:

git diff master..HEAD
diff --git a/README.md b/README.md
index e69de29..5d87a31 100644
--- a/README.md
+++ b/README.md
@@ -0,0 +1 @@
+Readme content\nNew content
diff --git a/my_new_file b/my_new_file
new file mode 100644
index 0000000..025d08b
--- /dev/null
+++ b/my_new_file
@@ -0,0 +1 @@
+my content

Note: HEAD is the last commit of the current working branch… HEAD could be replaced with MY-NEW-BRANCH in this context.
The same syntax applies on commit hashes. Ex: git diff ee621d6..4d2b83a

11. Merge branches

git checkout master
git merge MY-NEW-BRANCH

12. Reset a un-pushed merge

git reset --hard HEAD~1

Note: The number after HEAD represent the number of commits to reset. You can simple view the difference using git status and you will receive something like: Your branch is ahead of 'origin/master' by 1 commit.

And that it’s kind of it. Feel free to add questions or leave feedback.

For more information, visit Git official documentation.

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