Git History

Git History

Git History provides essential version control capabilities for managing codebase changes cleanly, predictably, and efficiently.

Core Concepts & Explanation

---

Git keeps a detailed record of every change made to your project.

You can use history commands to see what changed, when, and who made the change.

This is useful for tracking progress, finding bugs, and understanding your project's evolution.

---

Key Commands for Viewing History

• git log - Show full commit history
• git log --oneline - Show a summary of commits
• git show <commit> - Show details of a specific commit
• git diff - See unstaged changes
• git diff --staged - See staged changes

---

Best Practices for Viewing History

• Make frequent, meaningful commits to keep your history clear.
• Write clear commit messages so you and your team can understand changes later.
• Use git log --oneline for a quick overview of your commit history.
• Use git diff before committing to review your work.

---

See Commit History (git log)

Show a detailed list of all commits in your repository:

Example: Full Commit History
git log
commit 09f4acd3f8836b7f6fc44ad9e012f82faf861803 (HEAD -> master)
Author: kodersolution-test 
Date:   Fri Mar 26 09:35:54 2021 +0100

    Updated index.html with a new line

This command shows all commits, including author, date, and message.

Use the arrow keys to scroll, and press q to quit.

Tip: While viewing the log, you can search for a word by typing / followed by your search term
(for example, /fix), then press n to jump to the next match.

Press q at any time to quit.

---

Show Commit Details (git show <commit>)

See all the details and changes for a specific commit:

Example: Show Commit Details
git show 09f4acd
commit 09f4acd3f8836b7f6fc44ad9e012f82faf861803 (HEAD -> master)
Author: kodersolution-test 
Date:   Fri Mar 26 09:35:54 2021 +0100

    Updated index.html with a new line

diff --git a/index.html b/index.html
index 1234567..89abcde 100644
--- a/index.html
+++ b/index.html
@@ ...
+New Title

This command shows everything about a commit: who made it, when, the message, and the exact changes.

---

---

Compare Changes (git diff)

See what is different between your working directory and the last commit (unstaged changes):

Example: See Unstaged Changes
git diff
diff --git a/index.html b/index.html
index 1234567..89abcde 100644
--- a/index.html
+++ b/index.html
@@ ...
-Old Title
+New Title

This command shows changes you have made but not yet staged for commit.

---

Compare Staged Changes (git diff --staged)

See what is different between your staged files and the last commit:

Example: See Staged Changes
git diff --staged
diff --git a/index.html b/index.html
index 1234567..89abcde 100644
--- a/index.html
+++ b/index.html
@@ ...
-Old Title
+New Title

This command shows changes that are staged and ready to be committed.

---

Compare Two Commits (git diff <commit1> <commit2>)

See what changed between any two commits:

Example: Compare Two Commits
git diff 1234567 89abcde
diff --git a/index.html b/index.html
index 1234567..89abcde 100644
--- a/index.html
+++ b/index.html
@@ ...
-Old Title
+New Title

This command shows the differences between two specific commits.

---

Show a Summary of Commits (git log --oneline)

Show a short summary of each commit (great for a quick overview):

Example: Oneline Log
git log --oneline
09f4acd Updated index.html with a new line
8e7b2c1 Add about page
1a2b3c4 Initial commit

This command shows each commit on a single line for easy reading.

---

Show Commits by Author (git log --author="Alice")

See only the commits made by a specific author:

Example: Commits by Author
git log --author="Alice"
commit 1a2b3c4d5e6f7g8h9i0j
Author: Alice 
Date:   Mon Mar 22 10:12:34 2021 +0100

    Add about page

This command filters the log to show only commits by the author you specify.

---

Show Recent Commits (git log --since="2 weeks ago")

See only commits made in the last two weeks:

Example: Recent Commits
git log --since="2 weeks ago"
commit 09f4acd3f8836b7f6fc44ad9e012f82faf861803
Author: kodersolution-test 
Date:   Fri Mar 26 09:35:54 2021 +0100

    Updated index.html with a new line

This command shows only the commits made in a recent time frame.

---

Show Files Changed Per Commit (git log --stat)

See which files were changed in each commit and how many lines were added or removed:

Example: Log with Stats
git log --stat
commit 09f4acd3f8836b7f6fc44ad9e012f82faf861803
Author: kodersolution-test 
Date:   Fri Mar 26 09:35:54 2021 +0100

    Updated index.html with a new line

index.html | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

This command adds a summary of file changes to each commit in the log.

---

Show a Branch Graph (git log --graph)

See a simple ASCII graph of your branch history (great for visualizing merges):

Example: Log with Graph
git log --graph --oneline
* 09f4acd Updated index.html with a new line
* 8e7b2c1 Add about page
|\
| * aabbccd Merge branch 'feature-x'
|/

This command shows a simple graph of your branch and merge history.

---

Troubleshooting

• Can't see your changes? Make sure you have committed your work. Uncommitted changes won't appear in the history.
• Log is too long? Use git log --oneline or git log --since to make it easier to read.
• How do I quit the log view? Press q to exit the log or diff view.

---

Note: Exploring your history helps you understand what changed, when, and why.

---

---

Practical Terminal Workflow

Execute the following terminal commands to work with this concept in your workspace:

# Check repository status
git status

# View formatted log
git log --oneline -n 5

Best Practices & Pro-Tips

• Atomic Commits: Keep each commit small, focused, and dedicated to a single logical feature or bug fix.
• Imperative Commit Messages: Write commit titles in imperative mood (e.g., Fix CORS bug rather than Fixed CORS bug).
• Review Diff Before Staging: Run git diff to review unstaged modifications before adding files to the index.

Common Gotchas & Troubleshooting

• Detached HEAD State: Triggered when checking out a specific commit hash directly rather than a branch. Create a new branch with git switch -c <branch-name> to preserve edits.
• Accidentally Staged Binary Files: Run git restore --staged <filename> to remove the file from the index without altering your local workspace copy.

Self-Check Challenge

Open your terminal in a test project directory, execute git status, and verify your current working tree state. Practice running git log --oneline to review commit history.