How to Check If a Git Commit Message Contains Specific Text

Introduction

In this lab, you will learn how to efficiently search your Git commit history for specific text within commit messages. We will explore the git log --grep command to filter commits based on keywords, allowing you to quickly locate relevant changes in a large project.

You will also learn how to use git show to examine the details of a specific commit found through your search, and how to perform case-sensitive searches with git log --grep to refine your results. By the end of this lab, you will be proficient in using these Git commands to navigate and understand your project's history.

Skills Graph

%%%%{init: {'theme':'neutral'}}%%%% flowchart RL git(("Git")) -.-> git/BasicOperationsGroup(["Basic Operations"]) git(("Git")) -.-> git/BranchManagementGroup(["Branch Management"]) git/BasicOperationsGroup -.-> git/add("Stage Files") git/BasicOperationsGroup -.-> git/commit("Create Commit") git/BasicOperationsGroup -.-> git/diff("Compare Changes") git/BranchManagementGroup -.-> git/log("Show Commits") subgraph Lab Skills git/add -.-> lab-560067{{"How to Check If a Git Commit Message Contains Specific Text"}} git/commit -.-> lab-560067{{"How to Check If a Git Commit Message Contains Specific Text"}} git/diff -.-> lab-560067{{"How to Check If a Git Commit Message Contains Specific Text"}} git/log -.-> lab-560067{{"How to Check If a Git Commit Message Contains Specific Text"}} end

Use git log --grep to Search

In this step, we will learn how to search through our commit history using git log --grep. This is incredibly useful when you have many commits and need to find a specific one based on its message.

First, let's make a few more commits so we have something to search through. We'll add some more messages to our message.txt file.

echo "Adding a second message." >> message.txt
git add message.txt
git commit -m "Add second message"

You should see output similar to this:

[master <commit-id>] Add second message
 1 file changed, 1 insertion(+)

Now, let's add one more message and commit it:

echo "Adding a third message about the future." >> message.txt
git add message.txt
git commit -m "Add third message about future"

You should see output similar to this:

[master <commit-id>] Add third message about future
 1 file changed, 1 insertion(+)

Now we have three commits in our history. Let's use git log to see them all:

git log --oneline

You should see something like this (the commit IDs will be different):

<commit-id> Add third message about future
<commit-id> Add second message
<commit-id> Send a message to the future

Now, let's say we want to find the commit that mentions "future". We can use git log --grep for this:

git log --grep "future" --oneline

This command tells Git to show us only the commits whose messages contain the word "future". You should see output similar to this:

<commit-id> Add third message about future
<commit-id> Send a message to the future

Notice that only the commits with "future" in their message are shown. This is a powerful way to filter your commit history and quickly find what you're looking for.

The --grep option allows you to search commit messages for a specific pattern. This is very helpful when you have a large project with many commits and you need to find a commit related to a specific feature or bug fix.

Run git show for Specific Commit

In this step, we will learn how to view the details of a specific commit using the git show command. This command allows you to see exactly what changes were introduced in a particular commit.

First, let's get the commit ID of the first commit we made. We can use git log --oneline again to see the list of commits:

git log --oneline

Look at the output and find the commit message "Send a message to the future". Copy the short commit ID (the string of letters and numbers before the message). It should look something like a1b2c3d.

Now, use the git show command followed by the commit ID you copied. Replace <commit-id> with the actual ID you copied:

git show <commit-id>

You should see detailed information about that specific commit, including:

The commit ID, author, date, and message.
The changes made in that commit. For our first commit, it will show that the message.txt file was created and the line "Hello, Future Me" was added.

The output will look similar to this (the commit ID and date will be different):

commit <commit-id>
Author: Jane Doe <[email protected]>
Date:   Mon Aug 7 10:00:00 2023 +0000

    Send a message to the future

diff --git a/message.txt b/message.txt
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/message.txt
@@ -0,0 +1 @@
+Hello, Future Me

The git show command is incredibly useful for understanding the history of your project. You can use it to see exactly what changes were made in any commit, which is essential for debugging or understanding how a feature was implemented.

You can also use git show without a commit ID to see the details of the latest commit. Try it:

git show

This will show you the details of the commit "Add third message about future".

Remember, you can press q to exit the git show view and return to the command line.

Test Case-Sensitive Search

In this step, we will explore how git log --grep handles case sensitivity. By default, the search is case-sensitive, meaning "future" is different from "Future".

Let's try searching for "Future" (with a capital F) using git log --grep:

git log --grep "Future" --oneline

Based on our previous commits, only the first commit message "Send a message to the Future" contains "Future" with a capital F. The output should look similar to this:

<commit-id> Send a message to the future

Notice that the commit "Add third message about future" is not included because it uses a lowercase "f".

Now, let's try searching for "future" (with a lowercase f) again:

git log --grep "future" --oneline

This time, both commits that contain "future" (regardless of capitalization in the original message) should be displayed:

<commit-id> Add third message about future
<commit-id> Send a message to the future

Wait, that's not right! The previous step showed both commits when searching for "future". This is because the default behavior of git log --grep is case-insensitive on some systems or configurations.

To ensure a case-sensitive search, you can use the --i option (or --ignore-case). Let's try searching for "Future" case-sensitively:

git log --grep "Future" --oneline --i

This command tells Git to ignore case during the search. Now, both commits containing "future" or "Future" should be displayed:

<commit-id> Add third message about future
<commit-id> Send a message to the future

This demonstrates that while the default behavior might vary, using the --i option explicitly makes the search case-insensitive. If you need a strictly case-sensitive search, you would typically rely on the default behavior without --i. However, given the potential for variation, it's good practice to be aware of the --i option for case-insensitive searches.

Understanding case sensitivity in searches is important for accurately finding commits, especially in projects where commit message conventions might vary.

Summary

In this lab, we learned how to effectively search through Git commit history. We started by using git log --grep to filter commits based on specific text within their messages. This powerful command allows us to quickly locate relevant commits, especially in projects with extensive commit histories. We practiced this by creating several commits and then using --grep to find those containing the word "future".

We also explored how to view the details of a specific commit using git show and how to perform case-sensitive searches with git log --grep. These techniques provide essential tools for navigating and understanding the evolution of a Git repository.