Why Every Developer Must Master Git: From Basics to Practice (Part 1)

Git basics and practical pitfalls

Git commands look simple, but in production a merge conflict, an accidental rebase, or other mistakes can cause serious problems.

1. What is Git and why use it?

1.1 Evolution of version‑control systems

┌───────────────────────────────────────────────────────┐
│               Version‑control evolution               │
├───────────────────────────────────────────────────────┤
│   Local VCS   │   Centralized VCS   │   Distributed VCS │
│   RCS         │   CVS / SVN         │   Git / Mercurial │
│   Only local │   Single server     │   Every clone is a full repo │
│   No collaboration │   Single point of failure │   No single point of failure │
│   No network needed │   Network required │   Works offline │
└───────────────────────────────────────────────────────┘

1.2 Core advantages of Git

Distributed : each developer has a complete repository history locally.

Snapshot storage : Git stores full file‑state snapshots, not line‑by‑line diffs.

Data integrity : all objects are addressed by SHA‑1 hashes, making the data tamper‑proof.

Lightweight branch model : creating and switching branches has near‑zero cost.

Local operations : most actions run locally, providing fast feedback.

2. Core concepts

2.1 Three work areas

┌─────────────────────────────────────────────────────┐
│               Git work areas diagram               │
│   Working Directory ──git add──► Staging Area      │
│   (files on disk)          (index)                │
│          │                 │                     │
│          ▼                 ▼                     │
│   git commit ──► Local Repository ──git push──► Remote Repository │
└─────────────────────────────────────────────────────┘

2.2 File states

Untracked : new file not yet managed by Git.

Modified : file changed but not staged.

Staged : file added to the index, ready to commit.

Committed : file safely stored in the local repository.

2.3 Git object types

Blob : snapshot of file content, addressed by its content hash.

Tree : directory structure that records file names and references to blobs.

Commit : a commit object linking a tree, parent commits, author information, and a commit message.

3. Basic commands in practice

3.1 Initialize and clone

# Initialize a new repository
git init

# Clone a remote repository
git clone https://github.com/user/repo.git

# Clone into a specific directory
git clone https://github.com/user/repo.git my-folder

3.2 Daily development workflow

# 1. Check repository status
git status

# 2. View differences
#   working tree vs. staging area
git diff
#   staging area vs. HEAD (last commit)
git diff --staged

# 3. Stage changes
git add file.txt          # stage a single file
git add .                 # stage all changes in the current directory (use with care)
git add -p                # interactively select hunks

# 4. Commit staged changes
git commit -m "feat: add user login feature"

# 5. Inspect commit history
git log               # full history
git log --oneline     # concise one‑line per commit
git log --graph       # graphical representation
git log -p            # show diff for each commit

3.3 Conventional commit messages

# Example Conventional Commits
git commit -m "feat: add user login feature"
git commit -m "fix: correct order amount calculation"
git commit -m "docs: update README"
git commit -m "refactor: restructure order service"

# Type meanings
# feat     – new feature
# fix      – bug fix
# docs     – documentation update
# style    – code style changes (no functional impact)
# refactor – code refactor (no functional change)
# test     – test related changes
# chore    – build or tooling changes

4. .gitignore configuration example

# Build artifacts
target/
*.class
*.jar

# IDE configuration
.idea/
*.iml
.vscode/
.settings/

# Log files
*.log
logs/

# Environment files
.env
application-local.yml
application-dev.yml

# System files
.DS_Store
Thumbs.db

5. Common misconceptions

5.1 Difference between git add . and git add -A

git add .   # adds all changes in the current directory and its sub‑directories (new, modified, but not deletions)
git add -A  # adds all changes, including deletions and renames
git add -u  # adds changes to already tracked files only (no new files)

5.2 Commit message quality

# ❌ Poor examples
git commit -m "fix"
git commit -m "修改"
git commit -m "update"

# ✅ Good examples following Conventional Commits
git commit -m "fix: resolve concurrency issue in order status update"
git commit -m "feat: add user points feature"
git commit -m "refactor: extract common utils to common module"