Dev

2026/day-01/learning-plan.md

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+## 90-day personal DevOps learning plan
+
+# What is your understanding of DevOps and Cloud Engineering?
+Devops is the bridge between developers and operation.
+
+The main goals are:
+- Faster software delivery
+- Higher deployment reliability
+- Automation of repetitive tasks
+- Better collaboration between teams
+- Continuous monitoring and improvement
+
+Cloud Computing engineering focuses on designing, building, securing, and maintaining cloud-based infrastructure and services.
+The cloud platforms like: AWS, Azure, GCP, utho
+
+# Why you are starting learning DevOps & Cloud?
+- To switch and get more package 
+- To work on big startup, product base compnay, MNCs which help me to grow.
+- Skilled to become good Devops Engineer
+
+# Where do you want to reach?
+- I will work on big startup, product base compnay, MNCs.
+
+# How you will stay consistent every single day?
+- I will commit daily in this repo
+- I will win

2026/day-02/linux-architecture-notes.md

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+
+## The core components of Linux (kernel, user space, init/systemd)
+
+# Kernel
+The kernel is the core(heart) of the operating system.
+kernel is the bridge between software and hardware. 
+
+It directly interacts with the hardware and manages:
+- CPU scheduling
+- Memory management
+- Disk and file systems
+- Device drivers
+- Networking
+- Security and permissions
+
+# User Space
+User space is where normal applications run.
+Examples:
+- Bash shell
+- Nginx
+- Docker
+- Python programs
+- Editors like Vim
+
+Applications cannot directly access hardware.
+They must request services from the kernel using system calls.
+
+Flow : User command ==> Shell ==> System Call ==> Kernel ==> Hardware
+
+# init System (systemd)
+When Linux boots, the kernel starts the first process:
+systemd:
+
+- Starts services during boot
+- Manages background daemons
+- Handles logging
+- Restarts failed services
+- Tracks dependencies between services
+
+
+
+## How processes are created and managed
+A process is a running instance of a program.
+
+# Process Creation
+Linux commonly creates processes using:
+
+fork() ==> creates a copy of the current process
+exec() ==> replaces the copied process with a new program.
+
+# Process IDs (PID)
+Every process has a unique number:
+
+You can inspect processes using:
+ps aux
+top
+htop
+
+# Process States
+Running, Sleeping, Stopped, Zombie
+
+# Signals
+Linux controls processes using signals.
+SIGTERM	, SIGKILL , SIGSTOP	, SIGCONT	
+
+
+## What systemd does and why it matters
+systemd is the service manager used by most modern Linux systems.
+
+# Service Management
+Start/stop/restart services.
+
+systemctl start nginx
+systemctl stop docker
+systemctl restart ssh
+
+# Boot Management
+
+systemctl enable nginx
+
+# Logging
+systemd includes centralized logging.
+
+journalctl -u nginx
+
+# Automatic Recovery
+systemd can restart failed services automatically.
+
+Restart=always 
+
+