Linux Process Management and File System Architecture
Starting Processes in Linux
Processes can be started in two ways:
Foreground Processes
A foreground process runs normally on the terminal and occupies the shell until it finishes. The user cannot run another command until this process completes.
Example: $ ls or $ firefox
To start a process in the foreground, simply use the command_name.
Background Processes
A background process runs behind the terminal, allowing the user to continue working. A background process command ends with &.
Example: $ firefox
Computer Systems: Hardware, Networks & Software
1. Hardware — The Physical Foundation
Motherboard: The main printed circuit board that connects all the components of a computer. It provides the physical foundation and facilitates communication between all components.
Relation: ‘It allows the phone’s hardware parts to talk to each other to process the action.’
Processor (CPU): Known as the “brain” of the computer. It is responsible for making calculations, executing instructions, and controlling the overall operation of the system.
Relation: ‘The
vi Editor, Shell Variables and Shell Scripting I/O for Linux
vi Editor: Modes and Commands
The vi editor is a powerful and commonly used text editor in Linux and Unix systems. It is mainly used to create, edit, and manage text files such as configuration files, shell scripts, and program source code. vi works in different modes, which makes it efficient but slightly difficult for beginners.
Modes of the vi Editor
vi editor works in three main modes:
Command Mode
- Default mode when vi starts.
- Used for navigation, deleting text, copying, and saving files.
- Example commands:
Microcontroller Addressing Modes and Assembly Programming Concepts
1. Define Addressing Mode
Addressing Mode Definition
An addressing mode is the method a microcontroller uses to specify the location of the data (operand) required by an instruction. It determines how and from where the CPU fetches data—whether from a register, a memory address, an immediate constant, or through pointer-based access.
Why Different Addressing Modes Are Used
Different addressing modes are provided to achieve:
Programming Flexibility
Allows data to be accessed in multiple ways—direct,
SQL, PHP Integration and Web Security Best Practices
SIDE A: Database, SQL & PHP Integration
1. SQL Fundamentals (Chapters 8 & 9)
Data Definition Language (DDL) – Structure
Create DB:CREATE DATABASE publications; USE publications;
Create Table:
CREATE TABLE users (
id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
username VARCHAR(128),
password CHAR(255) -- Fixed length best for hashes
) ENGINE=MyISAM;Alter Table:
ALTER TABLE users ADD email VARCHAR(255);ALTER TABLE users DROP email;ALTER TABLE users MODIFY year SMALLINT;ALTER TABLE
Cybersecurity Techniques: Email Tracking, Keylogging, and HTTP Tunneling
Email Tracking Explained
Definition
E-mail tracking is the technique used to monitor and record information about emails sent, such as whether the email was opened, when it was opened, how many times it was opened, and from which location or IP address. It is mainly used during footprinting and information gathering to collect useful details about the recipient.
Explanation
E-mail tracking works by embedding a tracking element (such as a tracking pixel or link) inside the email. When the receiver opens
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