added lpic

Linux/LPIC1/directorys.md

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+# 📁 Linux Directory Structure & Basic Commands
+
+This document provides an overview of important Linux directories, their types, and essential file management commands.
+
+---
+
+## 📂 Directory Types
+
+| Type        | Description                                                                         |
+| ----------- | ----------------------------------------------------------------------------------- |
+| **Virtual** | Do not reside on disk; dynamically generated by the system (e.g., `/proc`, `/sys`). |
+| **Normal**  | Standard directories that store files and data on disk.                             |
+
+---
+
+## 🗂️ Common Linux Directories
+
+| Directory | Type    | Description                                                 |
+| --------- | ------- | ----------------------------------------------------------- |
+| `/etc`    | Normal  | System configuration files                                  |
+| `/opt`    | Normal  | Optional or third-party software packages                   |
+| `/bin`    | Normal  | Essential binary executables for all users                  |
+| `/sbin`   | Normal  | System binaries, typically for administrative tasks         |
+| `/lib`    | Normal  | Shared libraries and kernel modules                         |
+| `/home`   | Normal  | User home directories                                       |
+| `/proc`   | Virtual | Kernel and process information (virtual files)              |
+| `/srv`    | Normal  | Data for services provided by the system (e.g., web, FTP)   |
+| `/sys`    | Virtual | Kernel devices and system information                       |
+| `/usr`    | Normal  | Secondary hierarchy: programs, libraries, and documentation |
+| `/var`    | Normal  | Variable data: logs, mail, print spool, temporary files     |
+| `/dev`    | Virtual | Device files (e.g., disk, USB, terminals)                   |
+| `/mnt`    | Normal  | Mount point for temporary filesystems                       |
+| `/boot`   | Normal  | Boot loader files, kernel images                            |
+
+---
+
+## 🛠️ Basic File & Directory Commands
+
+| Command | Description                              |
+| ------- | ---------------------------------------- |
+| `cd`    | Change directory                         |
+| `ls`    | List directory contents                  |
+| `rm`    | Remove files or directories              |
+| `mkdir` | Create a new directory                   |
+| `touch` | Create an empty file or update timestamp |
+| `cp`    | Copy files or directories                |
+| `mv`    | Move or rename files or directories      |
+
+### 📘 Examples
+
+```bash
+cd /etc           # Navigate to /etc directory
+ls -l             # List files in long format
+rm file.txt       # Delete file.txt
+mkdir new_folder  # Create a directory named 'new_folder'
+touch file.txt    # Create a new empty file
+cp file1.txt file2.txt  # Copy file1.txt to file2.txt
+mv file.txt /home/user/ # Move file.txt to another directory
+```

Linux/LPIC1/runlevels.md

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+# Linux Runlevels Guide
+
+This document outlines the standard runlevels for **Red Hat** and **Debian**-based systems. Runlevels are used by `init` systems to define different states or modes of operation for the system.
+
+---
+
+## 📊 Runlevels Overview
+
+| Runlevel | Description                          | Red Hat      | Debian          |
+| -------- | ------------------------------------ | ------------ | --------------- |
+| 0        | Halt                                 | ✅ Supported  | ✅ Supported     |
+| 1        | Single User Mode                     | ✅ Supported  | ✅ Supported     |
+| 2        | Multi-user (No Network)              | ❌ (HaveNet)  | ✅ Supported     |
+| 3        | Multi-user (Network, No GUI)         | ✅ Supported  | ✅ Supported     |
+| 4        | Custom/User Defined                  | ✅ Supported  | ✅ Supported     |
+| 5        | Multi-user (GUI Mode) / Halt *(err)* | ❌ (GUI Mode) | ❌ (Halt/Error?) |
+| 6        | Reboot                               | ✅ Supported  | ✅ Supported     |
+
+> 💡 **Note**:
+>
+> * On **Red Hat**, runlevel 5 typically starts the system with a graphical user interface (GUI).
+> * On **Debian**, runlevel 5 is often unused or reserved for custom setups.
+> * Runlevel behavior can be customized depending on system configuration.
+
+---
+
+## 🔧 Commands
+
+### Check Current Runlevel
+
+```bash
+runlevel
+```
+
+### Change Runlevel
+
+```bash
+telinit <runlevel>
+```
+
+or
+
+```bash
+init <runlevel>
+```
+
+> ⚠️ Changing runlevels may stop or restart services. Use with caution, especially on production systems.
+
+---
+
+## 📚 Additional Tips
+
+* Modern Linux systems (especially systemd-based) may not rely on traditional runlevels. Instead, they use *targets*. Example:
+
+  ```bash
+  systemctl get-default
+  systemctl isolate graphical.target
+  ```
+