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Viewing History: Understanding Your Project's Past

Git's history is your project's story. Learning to read it is learning to understand your codebase.

🎯 The Big Picture​

Every commit tells a story. Who changed what. When. Why. Git's history is a complete record of your project's evolution.

Basic History Commands​

git log - The Foundation​

# Full history
git log

# One line per commit
git log --oneline

# Last 5 commits
git log -5

# With file statistics
git log --stat

# With actual changes
git log -p

Visual History​

# Graph view
git log --oneline --graph --all

# Decorated graph
git log --oneline --graph --all --decorate

# Show branch names
git log --oneline --graph --all --decorate --simplify-by-decoration

Finding Specific Commits​

By Author​

# Commits by specific author
git log --author="John Doe"

# Commits by email pattern
git log --author="@example.com"

By Date​

# Since specific date
git log --since="2024-01-01"

# Until specific date
git log --until="2024-12-31"

# Last week
git log --since="1 week ago"

# Between dates
git log --since="2024-01-01" --until="2024-12-31"

By Message​

# Search commit messages
git log --grep="bug fix"

# Case insensitive
git log --grep="bug" -i

By File​

# Commits affecting a file
git log -- file.txt

# Commits affecting a directory
git log -- src/

Understanding Commit Details​

git show - See a Commit​

# Show latest commit
git show

# Show specific commit
git show abc1234

# Show with statistics
git show --stat abc1234

git diff - See Changes​

# Changes in working directory
git diff

# Changes in staging area
git diff --staged

# Changes between commits
git diff commit1 commit2

# Changes in a file
git diff HEAD~1 HEAD -- file.txt

Real-World Scenarios​

Scenario 1: Who Broke This?​

# Find who last changed a file
git blame file.txt

# Find when a bug was introduced
git log -p -- file.txt | grep -B 10 "buggy code"

Scenario 2: What Changed?​

# What changed in last commit?
git show HEAD

# What changed between versions?
git diff v1.0 v2.0

# What changed in a branch?
git diff main..feature-branch

Scenario 3: Find a Feature​

# Find when feature was added
git log --grep="authentication" --oneline

# See the commit
git show <commit-hash>

My Take: History Is Your Friend​

I used to ignore Git history. I'd just work and commit. Never look back.

Then I learned: History tells you why things are the way they are.

  • Why was this code written this way?
  • When was this bug introduced?
  • Who knows about this feature?

History answers questions. Use it.

Key Takeaways​

  1. git log shows history - Learn its options
  2. git show shows commits - See what changed
  3. git diff shows differences - Compare versions
  4. History tells stories - Use it to understand code
  5. Search is powerful - Find commits by author, date, message

What's Next?​

Now that you can view history, let's learn about undoing changes. Next: Undoing Changes.

Remember: History is your project's memory. Learn to read it.