How to Check If a Git Repository Has Staged Changes

Introduction

In this lab, you will learn how to check if a Git repository has staged changes. You will use the git status command to view staged files and understand its output, which indicates the current state of your repository including modified, staged, and untracked files.

Furthermore, you will explore how to use git diff --cached to examine the specific changes that are currently in the staging area, allowing you to verify the differences between staged and unstaged changes within your repository.

Skills Graph

Use git status to View Staged Files

In this step, we'll use the git status command again to see how Git tracks changes after we've added a file.

First, make sure you are in your my-time-machine directory. If not, use the cd command:

cd ~/project/my-time-machine

Now, let's create a new file called notes.txt and add some content to it:

echo "Ideas for the future" > notes.txt

This command creates the file notes.txt with the specified text.

Next, let's tell Git that we want to track this new file. We use the git add command for this:

git add notes.txt

This command adds notes.txt to the staging area. The staging area is like a waiting room for changes before they are committed.

Now, let's check the status of our repository using git status:

git status

You should see output similar to this:

On branch master
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
        new file:   notes.txt

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

Notice the output now shows notes.txt under "Changes to be committed". This means the file is in the staging area, ready to be included in the next commit.

You might also see message.txt listed under "Untracked files". This is because we haven't committed the changes to message.txt yet from the previous steps. Git is showing us that there are still changes in the working directory that are not being tracked for the next commit.

Understanding the output of git status is crucial. It tells you the current state of your repository, showing which files have been modified, which are staged for commit, and which are untracked. This helps you keep track of your work and decide what to include in your next save point.

Check git diff --cached for Changes

In this step, we'll learn how to see the exact changes that are currently in the staging area using the git diff --cached command.

Remember from the previous step that we added notes.txt to the staging area. Now, let's see what changes Git is ready to commit.

Make sure you are in the ~/project/my-time-machine directory:

cd ~/project/my-time-machine

Now, run the following command:

git diff --cached

You should see output similar to this:

diff --git a/notes.txt b/notes.txt
new file mode 100644
index 0000000..a1b2c3d
--- /dev/null
+++ b/notes.txt
@@ -0,0 +1 @@
+Ideas for the future

This output shows you the difference between the staging area and the last commit. Since this is the first time we're staging notes.txt, Git shows it as a new file.

Let's break down the output:

• diff --git a/notes.txt b/notes.txt: This line indicates that we are comparing two versions of the file notes.txt.
• new file mode 100644: This shows that notes.txt is a new file.
• index 0000000..a1b2c3d: These are internal Git identifiers for the file's content.
• --- /dev/null: This represents the "empty" state before the file was added.
• +++ b/notes.txt: This represents the current state of the file in the staging area.
• @@ -0,0 +1 @@: This is a header indicating the lines that have changed. -0,0 means no lines were present in the original (empty) state, and +1 means one line is added in the new state.
• +Ideas for the future: The plus sign + indicates that this line has been added.

The git diff --cached command is incredibly useful for reviewing your staged changes before you commit them. It allows you to double-check exactly what you are about to save in your project's history. This helps prevent accidentally committing unwanted changes.

Press q to exit the diff view and return to the command line.

Verify Staged vs Unstaged Changes

In this step, we'll further explore the difference between staged and unstaged changes by modifying a file that is already being tracked by Git.

First, ensure you are in the ~/project/my-time-machine directory:

cd ~/project/my-time-machine

Now, let's add another line to our notes.txt file. We can use the echo command with >> to append text to an existing file:

echo "Another idea" >> notes.txt

This command adds the line "Another idea" to the end of notes.txt.

Let's check the status of our repository again:

git status

You should see output similar to this:

On branch master
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
        new file:   notes.txt

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:   notes.txt

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

Notice that notes.txt now appears in two sections:

1. Changes to be committed: This refers to the version of notes.txt that we added to the staging area in the previous step (which only contained "Ideas for the future").
2. Changes not staged for commit: This refers to the changes we just made to notes.txt (adding "Another idea"). These changes are in our working directory but have not been added to the staging area yet.

This is a key concept in Git: the staging area holds a snapshot of changes that are ready for the next commit, while the working directory contains the current state of your files, including changes that haven't been staged yet.

To see the difference between the working directory and the staging area, you can use the git diff command without any options:

git diff

This will show you the changes that are not staged. You should see output showing the line "Another idea" being added.

To see the difference between the staging area and the last commit (which we saw in the previous step), you use git diff --cached.

Understanding the difference between staged and unstaged changes, and how to view them with git status and git diff, is fundamental to using Git effectively. It gives you precise control over what goes into each commit.

Summary

In this lab, we learned how to check if a Git repository has staged changes. We started by using the git status command to view the current state of the repository, including files that have been added to the staging area. We saw how git status clearly indicates which files are "Changes to be committed".

Next, we explored the git diff --cached command to specifically view the differences between the staged changes and the last commit. This allowed us to see the exact content modifications that are ready to be committed. Finally, we reinforced the distinction between staged and unstaged changes, understanding that git status provides an overview while git diff --cached shows the detailed content of staged changes.