Chapter 3 — Viewing History

The Log

Example: Basic log

git log

commit e4f5a6b (HEAD -> main)
Author: Dariush Abbasi <[email protected]>
Date:   Mon Mar 10 14:32:00 2025 +0330

    Add greet function

commit a1b2c3d
Author: Dariush Abbasi <[email protected]>
Date:   Mon Mar 10 14:30:00 2025 +0330

    Initial commit: add README, index.js, and .gitignore

Example: One-line log

git log --oneline

e4f5a6b (HEAD -> main) Add greet function
a1b2c3d Initial commit: add README, index.js, and .gitignore

Example: Log with a graph

git log --oneline --graph --all

* f7g8h9i (feature/login) Add login page
| * e4f5a6b (HEAD -> main) Add greet function
|/
* a1b2c3d Initial commit

🧠 What happened? --graph draws the branch structure as ASCII art. --all shows all branches, not just the one you're on.

Example: Log for a specific file

git log --oneline -- README.md

a1b2c3d Initial commit: add README, index.js, and .gitignore

Example: Search commits by message

git log --oneline --grep="fix"

Example: Search commits by code change

git log --oneline -S "greet"

🧠 What happened? -S (the "pickaxe") finds commits where the number of occurrences of "greet" changed — i.e., where that string was added or removed.

Show a Specific Commit

Example: Show full commit details

git show e4f5a6b

commit e4f5a6b
Author: Dariush Abbasi <[email protected]>
Date:   Mon Mar 10 14:32:00 2025 +0330

    Add greet function

diff --git a/index.js b/index.js
index 1a2b3c4..5d6e7f8 100644
--- a/index.js
+++ b/index.js
@@ -1 +1,2 @@
 console.log('hello');
+function greet() { return 'hi'; }

Example: Show only the files that changed

git show --stat e4f5a6b

 index.js | 1 +
 1 file changed, 1 insertion(+)

Blame: Who Changed What

Example: See who wrote each line

git blame index.js

a1b2c3d (Dariush Abbasi 2025-03-10 14:30:00 +0330 1) console.log('hello');
e4f5a6b (Dariush Abbasi 2025-03-10 14:32:00 +0330 2) function greet() { return 'hi'; }

🧠 What happened? git blame annotates each line with the commit, author, and date of the last change. Despite the dramatic name, it's a tool for understanding history, not assigning fault.

Shortlog: Contributor Summary

Example: See commits grouped by author

git shortlog -sn

    15  Dariush Abbasi
     3  Jane Doe
     1  Bob Smith

Comparing Points in Time

Example: Diff between two commits

git diff a1b2c3d..e4f5a6b

Example: Diff between two branches

git diff main..feature/login

Example: What changed in the last 3 commits?

git diff HEAD~3..HEAD

Example: Just show file names that changed

git diff --name-only HEAD~3..HEAD

index.js
README.md

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