Why does every senior DevOps engineer tell you: Learn Linux first?

Before Kubernetes, before AWS, before Terraform… learn Linux. Here’s why 👇

Because no matter how shiny the cloud console looks, every outage eventually drags you down to the command line.

In real Linux/DevOps interviews, you are NOT judged by

how many commands you remember…

You are judged by how you THINK during production issues.

This poster covers real-world scenarios like:

• High load but CPU idle

• Disk space not freeing

• Zombie processes

• OOM killer issues

• Cron & network failures

💡 Interview Tip:

Network Pinger - Ping it

A simple command-line tool to ping a single IP address or a range of IP addresses to check their availability.

Features

• Ping a single IP address.
• Ping a range of IP addresses.
• Display results in a user-friendly format.
• Export data to excel.

Requirements

• Python 3.x
• Required libraries: requirements.txt

Installation

1. Clone the repository:

   git clone https://github.com/cuongitl/pyNetworkPinger.git
   cd pyNetworkPinger

1. Install the required libraries:

   pip install -r requirements.txt

Usage

Quick mode

Ping a Single IP Address

To ping a single IP address, run the following command:

python pingit.py <IP_ADDRESS>

Replace <IP_ADDRESS> with the actual IP address you want to ping.

Ping a Range of IP Addresses

This is a note; I'll write more fully later!

Install NetBox under 10 Minutes or less?

All steps are automated 100% by Python!

1. preparing_data: upload on config files to target host.

2. environment_setup: Installing Docker and Docker-Compose

3. Deploy containers: netbox, nginx, postgresql, redis, rq_worker...

4. Create new createsuperuser (Optional)

Details:

1.Upload config files:

- .env

- docker-compose.yml

- docker_install.sh

- netbox_full_setup.sh

- nsteam.it.crt

- nsteam.it.key

2. Installing Docker and Docker-Compose

- by docker_install.sh

3. Deploy docker containers: netbox, nginx, postgresql, redis, rq_worker...

- by netbox_full_setup.sh

4. Create new createsuperuser (Optional)

- by python code.

#!/bin/bash
:: Filename: docker_install.sh
:: Modified: 2025-05-02
:: Purpose: Quick install Docker on RHEL system.

# Built with ❤️ by Cuongitl (https://infra.lecuong.info)
# Reset color
RESET='\033[0m'

# Colors
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[0;33m'
BLUE='\033[0;34m'
MAGENTA='\033[0;35m'
CYAN='\033[0;36m'

# Update the system packages
echo -e "${YELLOW}Updating system packages...${RESET}"
sudo dnf update -y || { echo -e "${RED}Error updating system packages. Exiting.${RESET}"; exit 1; }

# Install the necessary packages
echo -e "${YELLOW}Installing necessary packages...${RESET}"
sudo dnf install -y dnf-utils || { echo -e "${RED}Error installing dnf-utils. Exiting.${RESET}"; exit 1; }

# Add the Docker repository
echo -e "${YELLOW}Adding Docker repository...${RESET}"
sudo dnf config-manager --add-repo https://download.docker.com/linux/rhel/docker-ce.repo || { echo -e "${RED}Error adding Docker repository. Exiting.${RESET}"; exit 1; }

# Install Docker
echo -e "${YELLOW}Installing Docker...${RESET}"
sudo dnf install docker-ce docker-ce-cli containerd.io -y || { echo -e "${RED}Error installing Docker. Exiting.${RESET}"; exit 1; }

# Start the Docker service
echo -e "${YELLOW}Starting Docker service...${RESET}"
sudo systemctl start docker || { echo -e "${RED}Error starting Docker service. Exiting.${RESET}"; exit 1; }

# Enable the Docker service to start automatically on system boot
echo -e "${YELLOW}Enabling Docker service to start automatically on system boot...${RESET}"
sudo systemctl enable docker || { echo -e "${RED}Error enabling Docker service. Exiting.${RESET}"; exit 1; }

# Verify the Docker installation
echo -e "${YELLOW}Verifying Docker installation...${RESET}"
sudo docker --version || { echo -e "${RED}Error verifying Docker installation. Exiting.${RESET}"; exit 1; }

# Install Docker Compose
echo -e "${YELLOW}Installing Docker Compose...${RESET}"
sudo curl -L "https://github.com/docker/compose/releases/download/v2.35.1/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose || { echo -e "${RED}Error downloading Docker Compose. Exiting.${RESET}"; exit 1; }
sudo chmod +x /usr/local/bin/docker-compose || { echo -e "${RED}Error making Docker Compose executable. Exiting.${RESET}"; exit 1; }

# Verify the Docker Compose installation
echo -e "${YELLOW}Verifying Docker Compose installation...${RESET}"
if [ -x "/usr/local/bin/docker-compose" ]; then
    echo -e "${GREEN}Docker Compose installed successfully.${RESET}"
else
    echo -e "${RED}Error verifying Docker Compose installation. Exiting.${RESET}"
    exit 1
fi

# (Optional) Create a symlink for easier access
echo -e "${YELLOW}Creating symlink for Docker Compose...${RESET}"
if [ ! -L "/usr/bin/docker-compose" ]; then
    sudo ln -s /usr/local/bin/docker-compose /usr/bin/docker-compose || { echo -e "${RED}Error creating symlink for Docker Compose. Exiting.${RESET}"; exit 1; }
else
    echo -e "${CYAN}Symlink for Docker Compose already exists. Skipping.${RESET}"
fi

# Verify the Docker Compose version
echo -e "${YELLOW}Verifying Docker Compose version...${RESET}"
docker-compose --version || { echo -e "${RED}Error verifying Docker Compose version. Exiting.${RESET}"; exit 1; }

echo -e

PowerShell script is to automate the process of copying a file  from a source directory to a destination directory

Purpose of the Script 

The purpose of this PowerShell script is to automate the process of copying a file (abc.xlsx) from a source directory to a destination directory, ensuring that: 

1.  The source file exists before attempting any further actions. 
2. The destination directory exists or is created if it doesn't. 
3. No overwriting of existing files occurs in the destination directory. If a file with the same name already exists, the script appends a numeric counter (-1, -2, etc.) to the filename to ensure that each copied file has a unique name. 
4. Safe file operations are ensured by checking for file existence and automatically generating a unique file name when necessary. 

Main Use Case:

 This script is useful when automating tasks like backing up files, copying reports, logs, or other documents, where the filenames may need to be adjusted based on the date or incremented to avoid conflicts with existing files. 

It ensures that the latest copy of the file is always transferred to the destination directory without any risk of overwriting existing files. 

 In summary, this script is designed to automate the process of file copying, making it safe, efficient, and organized, especially in environments where files with the same name (but potentially different versions) need to be handled daily or periodically.

backupfile.ps1

Configure Zabbix Agent: Active vs. Passive ?