[Linux] Linux 09 Digital Security & Docker

22 May 2026 in Study on Linux

Digital Security \& Encryption
Encryption \& Digital Signature
HTTPS, TLS, X.509 Certificate
Containerize Everything
Port, Volume, Dockerfile, Compose

[Linux] 08 Linux Shell Programming & Git

21 May 2026 in Study on Linux

Period 1: What is Shell \& First Script
- 🎯 Learning Objectives
Shell Basics 🐚
- Main Structure
- Common Shell Types
Types of Shell at One Glance 🐚
- Key Point 💡
Shebang (#!) 📝
- Example
- Purpose 🎯
- Common Interpreters
Two Ways of Running a Script ▶️
- 1. Run with Shell Command
- 2. Run as Executable File
Period 2: Variables \& Input
- 🎯 Learning Objectives
Variables 📦
- Variable Declaration
- Using Variables
- Key Points 💡
Environment Variable \& export 🌎
- Exporting a Variable
- Checking Environment Variables
- Key Points 💡
Special Variables ⚡
- Common Special Variables
- Example
read Command ⌨️
- Basic Example
- With Arguments
- Common Arguments
- Key Points 💡
Period 3: Control Flow, Functions \& Automation
- 🎯 Learning Objectives
Conditional Statements: if / elif / else / fi 🔀
- Basic Structure
- Example
- Key Points 💡
test Operator 🧪
Loop Statements 🔁
- for Loop
- while Loop
- Key Points 💡
Function 🛠️
- Defining a Function
- Calling a Function
- Example
- Key Points 💡
Debugging 🐞
- Common Debugging Options
- Example
- Key Points 💡
Period 4: Working / Staging / Repository
- 🎯 Learning Objectives
Why Version Management is Necessary 📂
- Why It Is Needed
- Without Version Control ❌
- With Git ✅
3 Areas of Git: Working / Staging / Repository 🗂️
- 1. Working Directory
- 2. Staging Area
- 3. Repository
- Git Workflow 🔄
git add \& git commit 📌
- git add
- git commit
- Key Points 💡
- Workflow 🔄
git status git diff git log 🔍
- git status
- git diff
- git log
- Key Points 💡
Period 5: Branch / Merge / Conflict
- 🎯 Learning Objectives
Branch 🌿
- Create a Branch
- Switch Branch
- Create and Switch at Once
- Key Points 💡
Branch Commands: branch switch checkout 🌿
- git branch
- git switch
- git checkout
- Key Points 💡
2 Ways of Merge: Fast-Forward vs 3-Way Merge 🔀
- Fast-Forward Merge
- 특징
- 3-Way Merge
- 특징
- Comparison 📊
Why Conflicts Occur? ⚠️
- Common Causes
- Example Situation
- Conflict Example
- Key Points 💡
Period 6: Remote Repository \& Collaboration
- 🎯 Learning Objectives
Remote Storage: Local ↔ Server Relationship 🌐
- Relationship Structure
- Main Workflow
- Key Points 💡
git push \& git pull 🔄
- git push
- u Option
- git pull
- How pull Works ⚙️
- Key Points 💡
git clone 📥
- Basic Command
- Example
- Commonly Used Options
clone vs init ⚖️
- git clone
- git init
- Comparison 📊
git fetch vs git pull 🔄
git fetch
- What It Does
- Workflow
- 특징 💡
git pull
- What It Does
- Internal Process
- Workflow
- 특징 💡
Main Difference ⚖️
When to Use Each 🛠️
- Use fetch
- Use pull
Learning Objectives: Git Advanced \& AI 🎯
git stash: Temporary Storage Management 🗄️⏳
- 🚨 Typical Use Scenario: The Production Hotfix
- ⌨️ Main Commands \& Operations
- 🔄 Restoring and Purging the Stack
Git Reset vs. Revert: Undoing Changes 🔄⚠️
- ⏳ History Modification: git reset
- The Three Reset Modes
- 🛡️ Safe History Reversal: git revert
- 📊 Summary: Reset vs. Revert
File Tracking Exclusion: .gitignore Rules 🛡️🚫
- 💡 Why Exclusion is Mandatory
- Core Exclusion Categories:
- ⌨️ Structural Syntax \& Pattern Rules
- ⚠️ The Golden Rule of .gitignore
- How to fix an already-tracked file:
Git Commit Message Conventions 📝✨
- 🏗️ The Standard 3-Part Structural Layout
- 🏷️ Prefixes: Commit Classification Types
- 📜 The 5 Golden Rules of Writing Effective Commits

[Linux] 07 Linux Storage & Monitoring

20 May 2026 in Study on Linux

Learning Objectives: Block Devices \& Disk Usage 🎯
Storage Devices
- 💡 Core Definition: Computer’s “Chest of Drawers”
- 🔍 The 3 Main Classes of Storage Hardware
Device Naming Rules
- 💿 1. SCSI / SATA \& USB Media Family Rule
- 🔍 Practical Naming Index:
- 🎛️ 2. High-Performance NVMe (M.2) Family Rule
- 🔍 NVMe Mapping Examples:
Storage Auditing — df vs du
- 🏠 1. df (Disk Free) — The “Whole Room View”
- 📦 2. du (Disk Usage) — The “Specific Box View”
- 📊 Metric Breakdown Comparison
- ⚠️ Real-World Discrepancy Note (Why the numbers might not match)
Hunting Large Files with du+sort and find -size
- 📂 1. Pipeline A: Sorting Folders by Size (du + sort + head)
- ⚙️ Breaking Down the Components:
- 🎯 2. Pipeline B: Targeting Specific Large Files (find -size)
- ⚙️ Breaking Down the Components:
- 💡 Core Summary Takeaway
Learning Objectives: File System \& Mount 🎯
File System
- 💡 Core Definition: The Storage Bookcase
- 🗂️ Linux vs. Windows File Systems
- 🔨 The Administrative Rule: Formatting
Mount — “Plugging a Disk into a Directory”
- 💡 Core Analogy: The Compartment and the Window
- 🗺️ The Architecture Mapping Flow
- ⚠️ Critical Precaution: Overwriting Directory Windows
/etc/fstab
- 💡 Core Definition: Permanent Storage Automation
- 📊 The 6-Column Syntax Layout
- ⚙️ Column Breakdown:
- 🛠️ Practical Workflow \& Safety Test
Mount Options — ro, noexec, and nosuid
- 🛡️ Core Security Options Breakdown
- 1. ro (Read-Only) 🛑✍️
- 2. noexec (No Execute) 🚫🏃‍♂️
- 3. nosuid (No Set-User-ID) ⚠️🎭
- ⌨️ Administrative Command Application
Learning Objectives: Disk Addition 🎯
Adding a Virtual Disk to VirtualBox / VMware
- 📦 1. The VirtualBox GUI Attachment Workflow
- ⚙️ 2. The VMware Workstation GUI Attachment Workflow
- 🔍 3. Post-Boot Administrative Verification via Terminal
- 📊 Anticipated Shell Output Structure:
Partitioning via fdisk
- 💡 Core Definition: Carving Up Raw Space
- ⌨️ Interactive fdisk Internal Command Menu
- 🛠️ Step-by-Step Creation Sequence (n Menu Workflow)
- 🔍 Post-Partitioning Verification
- 📊 Expected Output Structure:
Filesystem Formatting via mkfs
- 💡 Core Definition: Building the Storage Grid
- ⌨️ The Administrative Command Syntax
- ⚙️ Key Elements of the Command:
- 🔍 Post-Formatting Verification
- 📊 Expected Output Structure:
Permanent Mounting
- 💡 Core Definition: Preserving the Hardware Link
- 🛠️ Step-by-Step Implementation Workflow
- Step 1: Create a Dedicated Mount Point Folder 📁
- Step 2: Extract the Unique Partition UUID 🆔
- Step 3: Edit the File System Table Registry 📝
- ⚠️ Critical Precaution: The Safety Verification Test
Learning Objectives: Software RAID 🎯
What is RAID?
- 💡 Core Definition: Strength in Numbers
- 🛠️ Hardware RAID vs. Software RAID
- 📊 Summary Takeaway
RAID Levels 0, 1, and 5
- 🏎️ 1. RAID 0 (Striping — “Speed First”)
- 🛡️ 2. RAID 1 (Mirroring — “Safety First”)
- ⚖️ 3. RAID 5 (Distributed Parity — “The Sweet Spot”)
- 📊 Metric Matrix Comparison
Array Management via mdadm
- ⚙️ 1. Building a RAID Array (-create)
- 🛠️ Breaking Down the Parameters:
- 🔍 2. Auditing Real-Time Array Status (-detail)
- 📊 Key Metrics Provided in the Output:
- 🛑 3. Stopping and Deconstructing Arrays (-stop)
- 🔄 4. Re-Assembling Existing Arrays (-assemble)
Viewing RAID Status
- 📄 1. The /proc/mdstat File — Quick System Overview
- 📊 Understanding the /proc/mdstat Text Readout:
- 🛠️ 2. mdadm --detail — Detailed Administrative View
- 🔍 Key Fields Provided in the Detailed Output:
Learning Objectives: Logical Volume Manager (LVM) 🎯
The Core Necessity of LVM: Overcoming Static Partitioning
- 🛑 The Problem: The Hard Limits of Static Partitions
- 🚀 The Solution: What is LVM?
- 🧱 The 3-Layer Architecture Preview
Dynamic Storage Expansion: lvextend and resize2fs
- 💡 The Two-Step Expansion Philosophy
- ⌨️ Command Execution Breakdown
- Step 1: Expand the Logical Volume (lvextend) 📐
- Step 2: Expand the Filesystem Grid (resize2fs) 🗂️
- 🚨 Critical File System Architecture Exception: ext4 vs. XFS
Learning Objectives: System Monitoring 🎯
Introduction to System Monitoring
- 🏛️ The 3 Pillars of System Monitoring
Memory Auditing and Resource Distribution: The free Command
- 📉 1. Auditing Volatile Memory Space (free)
- 📊 Understanding the Memory Matrix Columns
- 🔄 2. Analyzing Virtual Memory: The Swap Space Row
Process Lifecycle Management: ps, kill, and pkill
- 🔍 1. Auditing Active Processes (ps)
- 🎯 2. Targeted Process Termination (kill)
- 📛 3. Bulk Termination by String Matching (pkill)
System Log Auditing: journalctl /var/log/syslog
- 📄 1. The Traditional Log Store: /var/log/syslog
- ⚡ 2. The Modern Unified Journaling Engine: journalctl
- ⌨️ Essential journalctl Operational Commands:
Learning Objectives: Daily Backup System 🎯
The Core Necessity: Why Backup?
- 🛑 The Core Risks: Why Data Disappears
- 🎯 The Operational Goals of a Backup System
tar Command
- 🧱 Understanding the Core Options (cvf vs. xvf)
- 1. Creating a New Archive Package ➕
- 2. Extracting an Existing Archive Package 📂
- ⚡ Combining Archiving with Compression (z / j)
Fast and Efficient Data Synchronization: The rsync Command
- 💡 The Core Advantage: Incremental Replication \& Delta Transfer
- ⌨️ Command Syntax and Key Options
- Parameter Breakdown:

[Linux] 06 Linux Networking

19 May 2026 in Study on Linux

Learning Objectives: Network \& Cabling 🎯
What is a Network?
- 💡 Core Definition
- 🏢 Everyday Analogy: The Logistics \& Post Office System
UTP Cable and RJ-45 Connector
- 🧵 1. UTP vs. STP: Choosing the Right Cable
- 📊 Quick Cable Type Breakdown
- ⚡ 2. Category Specifications (Cat.5e vs. Cat.6)
- 💎 3. The RJ-45 Connector Interface
OSI 7 Layers at a Glance
- 🗼 The Seven Logical Layers Breakdown
- 💡 Core Takeaways \& Mental Model
Learning Objectives: IP Addressing 🎯
- 🏛️ The Three Pillars of IP Configuration
IP Address
- 💡 Core Definition
- 🗺️ The Dual-Structure of an IP Address
- 📌 Critical Rules \& Characteristics to Remember
Private IP vs. Public IP
- 🔍 1. Core Differences Between Private \& Public IPs
- 📊 At-a-Glance Comparison
- 🛠️ 2. The Bridge: NAT (Network Address Translation)
Subnet Mask
- 💡 Core Definition: The Divider of Networks
- 🛠️ The Standard /24 Prefix (255.255.255.0)
- 📝 Key Rules of Subnet Math \& IP Allocations
Gateway
- 🚪 What is a Gateway?
- 🔍 Everyday Problem: The “No Internet” Trap
Learning Objectives: Router \& Routing 🎯
- 🏛️ The Three Pillars of Router \& Routing Objectives
Home Router
- 🏢 1. The Three Identities Inside a Single Device
- 🔌 2. Physical Decoupling: WAN vs. LAN Ports
- 💡 3. Key Background Service: The DHCP Server
NAT - How Private IP operates
- 🔄 1. Outbound \& Inbound Data Flow
- 💡 2. The Core Value of NAT: Overcoming Address Scarcity
Routing - finding a path to another network
- 💡 Core Definition: “One Stop at a Time”
- 🗺️ The Decision Flow: How a Node Paths Packets
- 📋 The Pathfinder’s Blueprint: The Routing Table
Learning Objectives: Ports, States, and Service Tests 🎯
TCP vs. UDP
- 🤝 1. TCP (Transmission Control Protocol): The Reliable Courier
- 🏹 2. UDP (User Datagram Protocol): The High-Speed Streamer
- 📊 Protocol Breakdown
Concept: Port
- 💡 Core Definition: The Application Identifier
- 🗂️ Port Ranges and Classifications
- 🔍 Real-World Multi-Tasking Scenario
Checking Open Ports with nc and telnet
- 🧰 1. nc (Netcat): The Swiss Army Knife of Networking
- 🔍 Interpreting nc Output States
- ☎️ 2. telnet: The Legacy Port Tester
- 💡 Core Troubleshooting Lesson: Ping vs. Port Check
Learning Objectives: DNS \& DHCP 🎯
DNS - Domain Name System
- 💡 Core Definition: The Internet’s Phonebook
- 🔄 The Domain Resolution Workflow
- 🐧 Checking DNS Configuration in Linux: /etc/resolv.conf
Local vs. Remote Name Resolution
- 🏠 1. /etc/hosts — The Local Priority Ledger
- 🌐 2. /etc/resolv.conf — The External DNS Gateway
- ⏱️ 3. The Lookup Order: Who Wins?
DHCP - Dynamic Host Configuration Protocol
- 💡 Core Definition: The Automated IP Administrator
- 🔄 The 4-Step Network Lease Handshake: DORA
- 💡 Core Takeaways
Learning Objectives: Netplan, SSH, and UFW 🎯
Netplan
- 💡 Core Definition: Declarative Network Management
- 🛠️ Practical Workflow: Modifying \& Applying Settings
- ⚠️ Critical Warning: The YAML Indentation Trap
SSH — Secure Shell
- 💡 Core Definition: Encrypted Remote Terminal
- 🛠️ Practical Usage: Connection Command Syntax
- 🔍 Real-World Connection Examples:
- 🛡️ The First-Time Connection Flow
SSH Key Authorization
- 💡 Core Definition: Passwordless Cryptographic Authentication
- 🛠️ Practical Implementation Workflow
- 🔒 4. Key Management Security Guidelines
UFW — Uncomplicated Firewall
- 💡 Core Definition: Simplified Port Protection
- 🛠️ Practical Administration: The Core Command Set
- 1. Checking the Operational State 📊
- 2. Toggling the Firewall State ⚙️
- 3. Opening Specific Application Ports (ALLOW Rules) 🟢
- 4. Closing or Deleting Rules (DENY/DELETE) 🔴

[Linux] 05 Linux Process & Service

18 May 2026 in Study on Linux

Ubuntu

[Linux] 04 Linux User, Group, and Permission Management

17 May 2026 in Study on Linux

Ubuntu

[Linux] 03 Advanced File Manipulation, Redirection, and Text Stream Processing

14 May 2026 in Study on Linux

Ubuntu

[Linux] 02 Linux Terminal, File System, and Package Management

13 May 2026 in Study on Linux

Ubuntu

[Linux] 01 Linux Foundations & Infrastructure Setup

12 May 2026 in Study on Linux

Ubuntu

Binance Auto Trading

08 Aug 2022 in Devlog on Crypto

Binance x Python

Pagination