Viewing History and Changes

What you will learn

• Understand the core purpose of Viewing History and Changes
• Master the basic usage and common options of Viewing History and Changes
• Learn how to use git status, git diff, and git log to inspect your working tree state, file differences, and commit history — the three most essential inspection tools for every Git user.
• Understand key concepts: git status: Current State
• Know when to use this feature and when to avoid it

Start with a problem

When you're new to Git, the hardest part is often not the commands themselves, but knowing which ones to learn first and which ones can wait. This section helps you build the right learning sequence.

One-Sentence Understanding

After making commits, you need three tools to inspect what's happening: git status for the current state, git diff for file differences, and git log for commit history.

git status: Current State

git status is the most frequently used Git command. It shows the state of your working tree, staging area, and current branch.

Basic Usage

# Full status
git status

# Compact mode (one file per line)
git status --short
# or
git status -s

Reading the Output

$ git status
On branch main
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
        new file:   README.md
        modified:   index.js

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:   src/app.js

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

Three sections at a glance:

Short Mode

$ git status -s
 M README.md        # Modified in working tree (space + M)
M  index.js         # Modified in staging area (M + space)
MM src/app.js       # Modified in both working tree and index
?? notes.txt        # Untracked (??)

git diff: File Differences

git status tells you which files changed; git diff tells you what exactly changed.

Three Common Comparisons

# Working tree vs staging area (unstaged changes)
git diff

# Staging area vs last commit (what the next commit will include)
git diff --staged
# or
git diff --cached

# Working tree vs last commit (all uncommitted changes)
git diff HEAD

Reading Diff Output

$ git diff
diff --git a/src/app.js b/src/app.js
index e69de29..3b18e51 100644
--- a/src/app.js
+++ b/src/app.js
@@ -0,0 +1,3 @@
+const greeting = "Hello";
+console.log(greeting);

Key parts:

• --- a/file = old version
• +++ b/file = new version
• @@ -0,0 +1,3 @@ = change location (old line 0, new line 1, 3 lines)
• Lines starting with + are additions
• Lines starting with - are deletions

File Names Only

git diff --name-only
git diff --name-status   # Shows files + change type

git log: Commit History

git log displays the commit history of your repository.

Basic Usage

# Full history
git log

# Compact (recommended for daily use)
git log --oneline

# Graphical (shows branch structure)
git log --oneline --graph --all

Useful Filters

# Last N commits
git log -5

# By date
git log --since="2025-01-01"
git log --until="2025-06-01"

# By author
git log --author="john"

# By file
git log -- src/app.js

# Custom format
git log --pretty=format:"%h - %an, %ar : %s"

Common format placeholders:

Single Commit Details

# Show latest commit details
git show

# Show a specific commit
git show abc1234

# Show statistics only
git show --stat

Daily Inspection Routine

# Three-step daily check
git status          # 1. Current state
git diff            # 2. Unstaged changes
git log --oneline -5 # 3. Recent commits

# Final check before committing
git status && git diff --staged

Try it yourself

1. Practice the view-history-and-changes command in a test repository and observe state changes before and after
2. Experiment with different options and compare the output differences
3. Simulate a real scenario where you would need to use this, and walk through the full process

Continue Learning

1. learning-path/undo-local-basics — Safe ways to undo local changes
2. commands/git-log — Advanced git log usage
3. commands/git-diff — Advanced git diff usage
4. commands/git-show — Git show reference

Further reading

Keep going on the same topic:

• Remote Sync
• Safe Ways to Undo Local Changes