TLDR: The idea of this post is to encapsulate the basic commands and concepts of GIT.
Well, it’s kind of a difficult question to answer. But, it’s a good one that everyone made one day. My answer it’s, shit happens. Sometimes you will need to roll back some changes because a new feature is not working fine or just check what did you do one week ago?.
Version control is the best way to identify the exact changes made in the application. Keep track of the changes, collaborate with other developers keeping track of all the changes that the team made.
There are several version control tools available in the market. In more recent times, git has become the most popular one.
There are some other tools available:
- TFS (Team Foundation Version Control)
- SVN (Subversion)
Git is a free and open-source distributed version control system designed to handle everything from small to very large projects with speed and efficiency.
In summary, Git will provide you a complete copy of the entire codebase of your project on every contributor’s computer. Codebase also can be called local repository.
So, the main functionality of Git is to track all changes in the codebase inside a local database.
The git snapshot is the state of the project files at a given point in time.
So, instead of maintaining a full copy of the entire codebase, Git will only maintain a snapshot of the project files at a given point in time.
There are three main states that project’s files can be in:
- Modified: The file has been modified. But that doesn’t mean that the file will be part of the next snapshot.
- Staged: The file change has been tracked by Git and will be part of the next snapshot.
- Committed: The staged files included in the previous step have been committed and are now ps part of the latest snapshot.
Install Git and configure it. Verify the install is working.
$ git --version git version 2.32.0
The config in git can work on different levels. But the main goal is to set the credencials that will identify the user changes. That can be locally or globally.
git config --global user.email "firstname.lastname@example.org" git config --global user.name "Educative Learner"
And verify the current config.
git config user.email git config user.name
If they work fine, you should be able to see your email and username.
So, when you want to create a new project, you need to create a new directory as you will see in the following command.
$ mkdir cats-project $ cd cats-project $ touch cats_list.txt
Inside the new directory, we can initialize the project with Git with the following command.
$ git init
git init command simply creates an empty repository in the current directory. Internally, Git will create a directory called
.git and inside that directory, and that directory will contain all the metadata that git will require for tracking the project.
git add command will help us to add files to the staging area. Git will track the content of the file and will keep track of the changes. So, enter the command in the current path.
➜ cats-project/ git:(master) $ git add .
. is the current directory. But, if you want to track a specific file like
cats_list.txt you can use the following command.
➜ cats-project/ git:(master) $ git add cats_list.txt
git status command will show the status of the project. It will show the files that are staged, modified, untracked, etc. That command doesn’t change or update anything.
➜ cats-project/ git:(master) ✗ git status On branch master No commits yet Untracked files: (use "git add <file>..." to include in what will be committed) cats_list.txt nothing added to commit but untracked files present (use "git add" to track)
➜ cats-project/ git:(master) ✗ git add cats_list.txt
➜ cats-project/ git:(master) ✗ git status On branch master No commits yet Changes to be committed: (use "git rm --cached <file>..." to unstage) new file: cats_list.txt ➜ cats-project/ git:(master) ✗
The information that is shown in the
git status command is very detailed. You can see the files that are untracked in the first block. Then, there is the
git add command, and finally, you can see the files that are staged.
Right now, we have a local repository that is tracking our folder. But, we need to commit the changes that we made in the project. So, we need to use the
git commit command.
A commit is a snapshot of the entire state of the project at that specific moment. The most recent snapshot of your repository is the HEAD. As soon as you create a new commit, the HEAD will point to the new commit.
➜ State 1 Commit 1 (HEAD -> master) ➜ State 2: After a second commit Commit 2 (HEAD -> master) -> Commit 1 (master) ➜ State 3: After a third commit Commit 3 (HEAD -> master) -> Commit 2 (master)
It’s mandatory to add a message to the commit. The message will be used to identify the commit. To do so, we can use the
git commit -m 'Text to be included to describe the commit content' command with the
-m flag and then the text. The idea of this text is to make sure it is sufficiently descriptive, and give a clear idea of what the commit is about.
➜ cats-project/ git:(master) ✗ git commit -m 'Initial commit' [master (root-commit) 033c02f] Initial Commit 1 file changed, 0 insertions(+), 0 deletions(-) create mode 100644 cats_list.txt ➜ cats-project/ git:(master) git status On branch master nothing to commit, working tree clean
After the commit command is executed, the
git status command will show the message nothing to commit, working tree clean.
git log command will show the history of commits performed in the project. If the project has multiple collaborators, you can find several commits and his authors.
➜ cats-project/ git:(master) git log commit 033c02f2726c0d5e64ee09b97cbf50472d034f1c (HEAD -> master) Author: Ramiro Andres Bedoya <email@example.com > Date: Wed Sep 22 20:43:16 2021 -0500 Initial Commit (END)
You can press
esc key to exit the command.
As you can see, each log will contain information about the author of the commit, the date of the commit, and the message of the commit. Another important piece of information is the unique hash of the commit. That hash helps to identify the commit. That hash uses the cryptographic hash function SHA-1.
git reset command is a powerful tool to undo commits. For example, if you want to undo the last commit, you can use the following commands.
➜ cats-project/ git:(master) touch dogs_list.txt ➜ cats-project/ git:(master) ✗ git add dogs_list.txt ➜ cats-project/ git:(master) ✗ git commit -m 'dogs list' [master 9588849] dogs list 1 file changed, 0 insertions(+), 0 deletions(-) create mode 100644 dogs_list.txt ➜ cats-project/ git:(master) git status On branch master nothing to commit, working tree clean
I create a new file call
dogs_list.txt and, I add it to the staging area. Then, I commit the changes.
This flag is used to modify or update the changes from the previous commit without removing them completely. The complete command for the latest commit is
git reset --soft HEAD~1. The
HEAD~1 indicates how many commits you want to go back.
➜ cats-project/ git:(master) git reset --soft HEAD~1 ➜ cats-project/ git:(master) ✗ git status On branch master Changes to be committed: (use "git restore --staged <file>..." to unstage) new file: dogs_list.txt
This flag changes the state of the committed files to
This flag is used to remove the complete changes from the previous commit. So, with the
git reset --hard HEAD~1 command, the state will show the message nothing to commit, working tree clean.
I believe this is one of the most common causes. Let’s say that you are working in a special feature for the project. There is a lot of changes but the development is still in progress. Let’s say that you need to fix a bug with a high priority. So, here is the best situation where the branches are used.
If you are working with branches, you can easily commit your changes to the current branch, then change into main and create a new branch. After that, you can fix the bug and merge those changes into the main. Finally, you can go back to the feature branch and resume the work.
In Git, the master branch is the default branch created in a new repository.
All the commits executed in the previous example will be stored in the master branch. However, if you want to create a new branch, you can do it with the
git branch command.
The idea with the branches is that you can create new branches that divert away from the master and you can continue to do your work from that new branch. The changes made in the new branch only will be reflected in this branch and won’t affect the master branch.
The task that Git does when a new branch is created is a new pointer to the current commit of the project. Therefore, the master branch has its pointer, and when you take a new branch out from the master branch, your new branch will have its pointer separate from the master.
Let’s see an example of that pointer. Right now we have the following commits:
| Commit 1 | - master | Commit 2 | | Commit 3 | | Commit 4 |
When you create a new branch, a new pointer is created pointing to the latest commit.
[new_branch] \ | Commit 1 | - master | Commit 2 | | Commit 3 | | Commit 4 |
The Commits created on the new branch are separated from the master branch.
| Commit 1a | - [new_branch] | Commit 1b | \ | Commit 1 | - [master] | Commit 2 | | Commit 3 | | Commit 4 |
You can keep performing commits into the master branch.
[new_branch] - | Commit 1a | | Commit 1b | | new commit | - [master] \ | Commit 1 | | Commit 2 | | Commit 3 | | Commit 4 | ➜ cats-project/ git:(main)
You can create branches from any other branch. A new branch doesn’t necessarily have to come from the master branch. The follow image descrive a tipical workflow with multiple branches.
This one is a really powerful command. It allows you to create new branches, delete branches, rename branches, and list all the branches in the project.
➜ cats-project/ git:(main) git branch * master
git branch command will show all the branches in the project. The one with the asterisk is the current branch. To create a new one, let’s execute the following command
➜ cats-project/ git:(main) git branch new_branch ➜ cats-project/ git:(main) git branch * master new_branch
git branch command again will show the new branch. But you’ll realize that the new branch is not the current branch. To make the new branch the current one, you can use the
git checkout command.
With this command, git will allow you to change the current branch. Once you create the new branch with the previous command, you can switch into that new branch created with the following command:
➜ cats-project/ git:(main) git checkout new_branch Switched to branch 'new_branch' ➜ cats-project/ git:(new_branch) ➜ cats-project/ git:(main) git branch master * new_branch
You can combine both commands with the flag
-b, creating the branch and then switch over to it.
➜ cats-project/ git:(main) git branch * master ➜ cats-project/ git:(main) git checkout -b new_branch Switched to a new branch 'new_branch' ➜ cats-project git:(new_branch)
At some point, you may have a typo while creating the branch, but after several commits, you realize that error. So, to rename the branch use the following commands:
➜ cats-project/ git:(main) git checkout new_banch Switched to a new branch 'new_banch' ➜ cats-project git:(new_banch) git branch -m new_branch ➜ cats-project git:(new_branch)
If you do not want to change into the branch to be renamed, you can use the following command:
➜ cats-project git:(main) ➜ cats-project git:(main) git branch -m new_bach new_branch ➜ cats-project git:(main)
As I wrote before, the
git branch is a powerful command. With just the
-d flag, you can remove a specific branch. Just be sure to change into another branch before deleting it.
➜ cats-project git:(main) git branch -d new_branch Deleted branch new_branch (was 033c02f).
I must to confess that I learn about this feature really late, but after that, it changes everything.
There is a very specific case in which this command has improved my life. Many times, I was working on a specific feature, but it’s not ready. The code is totally unpresentable to perform a commit, but I need to change into another branch real quick.
This is where
git stash comes in to shine. This command stores the staged and modified fields in a kind of cache, making all the current branch clean of changes.
Let’s see the following scenario
➜ cats-project/ git:(main) git checkout -b new_branch Switched to a new branch 'new_branch' cats-project/ git:(new_branch) echo Work In progress File > file1.txt cats-project/ git:(new_branch) ✗ cat file1.txt Work In progress File ➜ cats-project git:(new_branch) ✗ git status On branch new_branch Untracked files: (use "git add <file>..." to include in what will be committed) file1.txt nothing added to commit but untracked files present (use "git add" to track)
In the code above, we are in the new branch and create a new file called
file1.txt. If you hit
git status, a new untracked file will be shown.
But, right now I need to change into another branch, and I don’t want to lose the changes I made in the new branch. So, I can use the
git stash command to save the changes in the new branch.
Steps to perform the stash:
git stashin the branch you want to stash. If the file is new, make sure to hit
-uflag to include the untracked files
- The console will show a message like this one:
Saved working directory and index state WIP on new_branch: 033c02f Initial Commit
- Now, you can switch into another branch and make the corresponding changes.
- To restore the changes, just hit
git stash apply. And you will see the previous changes.
NOTE: if you want to remove the stash, you can use the
git stash drop command.
Let’s say that you decide not to use
git stash command. Well, git would have prevented you from switching over to another branch if the other branch had changes that would be overwritten with the new uncommitted changes.
But, there is always the possibility to commit the unfinished work even if that work is failing, and then switch over to another branch.
One of the biggest benefits of using git is the ability to have multiple branches in the same project without any interference from changes in another branch. This is very useful when you have branches like a feature branch, a hotfix branch, a release branch, and a master branch. Well, when you finish a feature or hotfix, you can merge it into the master branch. So, all the changes created in the feature branch will be present in the
I have the following scenario:
First, I have a
master branch and another branch with a new feature called
master branch, I have the file
/hola-git.md, and in the feature branch, I have the files
The idea is to merge the feature branch
type-of-cats into the
master branch. By the end of the merge, the master branch will have the files
So, to perform the merge operation, I can use the following steps:
Switch to the branch in which you want to contain the merging branch needed to be merged. For example, I want to merge the
type-of-catsbranch into the
masterbranch. So I will switch to the
- Use the command:
git checkout master
- Use the command:
Then I will merge the
type-of-catsbranch into the
masterbranch using the command
git merge <branch_to_be_merged>.
- Use the command:
git merge type-of-cats.
- Use the command:
In most cases you will see a
vi application opening the merge commit with the following message:
Merge branch 'type-of-cats' # Please enter a commit message to explain why this merge is necessary, # especially if it merges an updated upstream into a topic branch. # # Lines starting with '#' will be ignored, and an empty message aborts # the commit. ~ ~ ~ ~ ~ "~/workspace/gatitos-app/.git/MERGE_MSG" 6L, 254C
esc and then in the bottom of the screen hit
:wq to save the changes and exit.
lsto see the files that are present in the master branch.
➜ cats-project/ ramiroandres$ ls gatitos-hardcore.md gatitos-panzones.md gatitos-tiernos.md hola-git.md
git log should list the commits from the
master branch and the
type-of-cats. You can verify this by yourself in the terminal provided below:
➜ cats-project/ ramiroandres$ git log commit ceb35a5661d24de14ee6e1fcdad1c418847551ad (HEAD -> master) Merge: 7228b3a 873a27f Author: Ramiro Andres Bedoya Escobar <firstname.lastname@example.org> Date: Fri Nov 26 08:54:13 2021 -0500 Merge branch 'type-of-cats' commit 7228b3a03e328832828cc5dc1ba687713820da36 Author: Ramiro Andres Bedoya Escobar <email@example.com> Date: Fri Nov 26 08:40:58 2021 -0500 gatitos panzones commit 873a27fbad108dbf7ae0ac1de9ee93e7dcab2c78 (type-of-cats) Author: Ramiro Andres Bedoya Escobar <firstname.lastname@example.org> Date: Fri Nov 26 08:40:05 2021 -0500 new types of cats commit 73c2590eae23c33d7a84f5066e0d9f0f56fcf91b Author: Ramiro Andres Bedoya Escobar <email@example.com> Date: Fri Nov 26 08:37:58 2021 -0500 Initial Files
Well, merge conflicts are a common problem in git, especially when there are more than one contributor. Most of the time merge conflict exists when: A file has been changed at the same line or when a file has been removed in one branch and being updated in another one. When the branches are merged, git can not know which one is the correct one. So, the developer has to resolve the merge conflict manually.
To generate a merge conflict, you can use the following steps:
First: Create a new branch and make the changes in the branch.
➜ cats-project/ ramiroandres$ git checkout -b feature/new-fat-cats ➜ cats-project/ ramiroandres$ echo "Persian cat can weight between 7 to 12 lbs" > gatitos-panzones.md ➜ cats-project/ ramiroandres$ git add gatitos-panzones.md ➜ cats-project/ ramiroandres$ git commit -m 'updated contents of gatitos-panzones.md in feature/new-fat-cats'
Then, we will switch to the master branch and make changes in the same file
➜ cats-project/ ramiroandres$ git checkout main ➜ cats-project/ ramiroandres$ echo "American Shorthair cat can weight between 8 to 12 lbs" > gatitos-panzones.md ➜ cats-project/ ramiroandres$ git add gatitos-panzones.md ➜ cats-project/ ramiroandres$ git commit -m 'updated contents of gatitos-panzones.md in master'
So, right now we have two branches with the same file updated. So, let’s check what happens when two branches are merged.
Make sure you are in the
master branch and execute:
git merge feature/new-fat-cats
So, as we saw before, git can not merge the branches because there is a merge conflict due to the file
gatitos-panzones.md having been updated in both branches.
So, the first step is to open the file with the conflict and resolve it manually.
In the output log, the message says the file name:
CONFLICT (content): Merge conflict in gatitos-panzones.md. So, open gatitos-panzones.md file and take a look.
Opening the file, you need to identify the conflicts founding the tag
<<<<<<< HEAD and
>>>>>>> feature/new-fat-cats. Those will separate the differences in each branch by the line
If you are using a text editor like VS Code, you can see the options of Accept Current Change | Accept Incoming Change | Accept both changes.
After you decide which one is the correct one, you can edit the file and resolve the conflict.
To finish the merge process, add the file to a staged state and commit the changes.
git add gatitos-panzones.md
git commit -m 'resolved conflict in gatitos-panzones.md'
if I hit
git log command, I should see the following:
That commit will contain a special line that tell us that the merge was successful.
Merge: 35a8114 d048c2f
Most people think that git is the same thing as github, but the truth is that git is the software that allows us to control the version control of our projects.
Then, you can connect your local repository to a remote repository. That repository can be github, bitbucket, gitlab, etc.
Github is a popular repository hosting service that allows you to share your projects with the world.