There are several ways to find empty fields in a JSON file, depending on your preferences and the tools available. Here are the most common approaches: Using jq (Command Line) jq is a powerful JSON processor that's perfect for this task: # Find empty strings jq -r 'paths
LaTeX is the standard for typesetting mathematical formulas. You can use it in many environments, including Markdown, Jupyter Notebooks, Overleaf, and more. 1. Math Modes Display Math: Use double dollar signs or \[ ... \]: $$E = mc^2$$ or \[ E = mc^2 \] Renders as: \[ E = mc^2 \] Inline Math: Use single dollar signs:
Overview This document provides practical examples of good and bad database design patterns, illustrated with MermaidJS diagrams. Each example shows the problem, explains why it's problematic, and demonstrates the correct approach. 1. Table Structure Design ❌ Bad Example: Denormalized Customer Table erDiagram CUSTOMERS_BAD { int customer_id PK string
Overview Database design is the process of creating a detailed data model of a database that defines the logical structure, relationships, constraints, and organization of data. Good database design ensures data integrity, reduces redundancy, optimizes performance, and supports business requirements. Database Design Process 1. Requirements Analysis Gather Business Requirements * Identify
Table of Contents 1. Introduction 2. Basic Syntax 3. Metacharacters 4. Character Classes 5. Quantifiers 6. Anchors 7. Groups and Capturing 8. Lookaheads and Lookbehinds 9. Flags/Modifiers 10. Common Patterns 11. Examples 12. Best Practices 13. Tools and Testing Introduction Regular expressions (regex or regexp) are powerful pattern-matching tools
Array Structures Static Array graph LR A[Index 0 Value: 10] --> B[Index 1 Value: 20] B --> C[Index 2 Value: 30] C --> D[Index 3 Value: 40] D --> E[Index 4 Value: 50] style A fill:#e1f5fe style B fill:#e1f5fe
Table of Contents 1. Introduction 2. Time and Space Complexity 3. Basic Data Structures 4. Advanced Data Structures 5. Fundamental Algorithms 6. Algorithm Design Paradigms 7. Problem-Solving Strategies 8. Common Algorithm Patterns Introduction Data structures and algorithms form the foundation of computer science and software engineering. Understanding these concepts is
Special Variables $_ - Last argument of previous command mkdir my_directory && cd "$_" cp file.txt /backup && ls "$_" # ls /backup !! - Repeat last command sudo !! # Run last command with sudo echo "test" && !! # Repeat the echo !$ - Last argument of
Table of Contents 1. Introduction 2. Core Principles 3. Key Concepts 4. Advanced Topics 5. Benefits and Drawbacks 6. Examples Introduction Object-Oriented Programming (OOP) is a programming paradigm that organizes code around objects rather than functions and logic. It's based on the concept of "objects" which
Table of Contents 1. Introduction 2. Installation and Setup 3. Rails Architecture (MVC) 4. Getting Started 5. Models and ActiveRecord 6. Views and ERB Templates 7. Controllers 8. Routing 9. Database Migrations 10. Associations 11. Validations 12. Forms and Form Helpers 13. Authentication and Authorization 14. Testing 15. Deployment 16.
Table of Contents 1. Introduction 2. Installation 3. Basic Syntax 4. Data Types 5. Variables 6. Control Structures 7. Methods 8. Classes and Objects 9. Modules 10. Exception Handling 11. File I/O 12. Gems and Libraries 13. Best Practices 14. Advanced Topics Introduction Ruby is a dynamic, open-source programming
What is SCSS? SCSS (Sassy CSS) is a syntax of Sass (Syntactically Awesome Style Sheets), which is a CSS preprocessor that extends the capabilities of regular CSS. SCSS allows developers to write more maintainable, organized, and powerful stylesheets by adding programming-like features to CSS. Key Features 1. Variables Store reusable
Linux
Method 1: Using dpkg-reconfigure (Recommended for Ubuntu/Debian) This is the cleanest and most Ubuntu-appropriate method: Restart the SSH service: sudo systemctl restart ssh Reconfigure OpenSSH server to regenerate keys: sudo dpkg-reconfigure openssh-server Remove existing host keys: sudo rm /etc/ssh/ssh_host_* Method 2: Manual key generation If you
Linux
Table of Contents * What is Flatpak? * Key Features * Installation * Basic Usage * Application Management * Security & Sandboxing * Permission Management * Advanced Features * Troubleshooting * Best Practices What is Flatpak? Flatpak is a universal package management system for Linux distributions that provides a sandboxed environment for running desktop applications. It was developed as an
Linux
Method 1: Using apt-mark hold (Recommended) This is the most common and recommended method: # Hold a specific package sudo apt-mark hold package-name # Hold multiple packages sudo apt-mark hold package1 package2 package3 # Check which packages are held apt-mark showhold # Remove the hold sudo apt-mark unhold package-name Example: sudo apt-mark hold apache2
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What are Source Maps? Source maps (also called map files) are special files that create a bridge between your original source code and the transformed/compiled code that runs in the browser. They have the file extension .map and are typically named after the corresponding JavaScript file (e.g., bundle.
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What is HEAD? Before understanding "detached HEAD," let's clarify what HEAD is in Git: * HEAD is a pointer that refers to the current branch you're working on * Normally, HEAD points to a branch name (like main or feature/login) * The branch name then points
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Table of Contents 1. What is Git? 2. Installation 3. Basic Configuration 4. Core Concepts 5. Essential Commands 6. Working with Repositories 7. Branching and Merging 8. Remote Repositories 9. Common Workflows 10. Best Practices 11. Troubleshooting What is Git? Git is a distributed version control system that helps you
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Clipboard Redirection To configure clipboard redirection, edit the VMware configuration file: sudoedit /etc/vmware/config Add or modify the following line: ClipboardDirection=1 Use this option to specify the clipboard redirection policy. Valid values are as follows: * 0 - Deactivate clipboard redirection. * 1 - Enable clipboard redirection in both directions.
Python
Virtual environments are isolated Python environments that allow you to install packages for specific projects without affecting your system-wide Python installation. Why Use Virtual Environments? * Dependency Isolation: Different projects can use different versions of the same package * Clean Development: Avoid polluting your global Python installation * Reproducibility: Easily share project dependencies
Linux
Both commands terminate processes but differ in how they identify targets: kill * Requires process ID (PID) * Syntax: kill [options] <PID> * More precise targeting * Example: kill 1234 pkill * Accepts process name patterns * Syntax: pkill [options] <pattern> * Can target multiple processes at once * Example: pkill firefox Key differences:
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Basic Installation Linux/macOS curl https://rclone.org/install.sh | sudo bash Windows (using Powershell as Admin) winget install Rclone.Rclone Essential Commands Configure new remote rclone config List directories rclone ls remote:path Copy files rclone copy source:path dest:path Sync directories (source to destination) rclone sync source:
Linux
awk is a powerful text processing language. Here are some advanced use cases: 1. Advanced Field Processing Input (grades.csv): Alice,Math,85,A,Science Bob,Math,92,A,Arts Charlie,Math,78,B,Science Command: # Calculate average score for students with grade A awk -F',' '$5
Linux
awk is a powerful text processing language. Here are common use cases with examples: Basic Syntax awk 'pattern { action }' input_file 1. Print Specific Columns # Print first and third columns awk '{print $1, $3}' file.txt # Print last column using NF (Number of Fields) awk '