Author: Rahul

If you’ve spent any significant amount of time working in a Linux environment, you’re likely familiar with the SCP (Secure Copy) command. This handy tool enables you to securely transfer files between different hosts over a network using the SSH (Secure Shell) protocol. However, there might be instances where you encounter the error message: ‘bash: scp: command not found’. This article aims to help you troubleshoot this error, getting you back to work as soon as possible. What Causes the Error? The error message ‘bash: scp: command not found’ typically appears when the SCP command isn’t installed or accessible on…

This guide is designed to assist you in finding out the size of databases and tables on your PostgreSQL server, making it easier to manage your data effectively. To start, you’ll need to access your server via the command line and establish a connection with the PostgreSQL server. Here’s how you can determine the sizes of your databases and tables in PostgreSQL using straightforward commands. 1. Determine PostgreSQL Database Size Using SQL Queries To find out how much space your PostgreSQL database occupies, follow these steps: First, open a terminal and log into the PostgreSQL command interface: sudo -u postgres…

PostgreSQL is a powerful open-source relational database management system, known for its robustness and extensibility. As a database administrator or developer, one of the fundamental tasks you’ll often need to perform is listing databases and tables within PostgreSQL. In this step-by-step tutorial, we will walk you through the process of listing databases and tables using various methods and PostgreSQL commands. Listing Databases in PostgreSQL Open your terminal or command prompt. To access the PostgreSQL command-line interface (psql), type the following command, replacing your_username with your actual PostgreSQL username: psql -U your_username You will be prompted to enter your password. Once…

Sendmail is a MTA (Mail Transfer Agent) server used for transferring email from between different hosts. Sendmail uses SMTP (Simple Mail Transfer Protocol) protocol. Most of the system administrators preferred to use Sendmail server as MTA than other MTAs. RHEL 5 or its earlier versions were using Sendmail as a default mail server, But newer version’s of RHEL based systems adapted postfix as a default mail server. Most of the users are familiar with Sendmail and want to use it with version 6 also. This article will help users for installing Sendmail server on RHEL 7/6/5 or with minimal configuration.…

In the ever-expanding world of big data, Elasticsearch has emerged as a front-runner in the search and analytics engine space. Its ability to handle large volumes of data efficiently makes it a go-to choice for many organizations. This article delves into the process of setting up a multi-node Elasticsearch cluster on an Ubuntu server, providing a detailed and comprehensive guide for systems administrators, DevOps engineers, and data professionals. This guide focuses on establishing a three-node Elasticsearch cluster on Ubuntu, specifically configured for the following nodes: NODE_1: 192.168.10.101 NODE_2: 192.168.10.102 NODE_3: 192.168.10.103 What is Elasticsearch? Elasticsearch is an open-source, distributed search…

Nagios is an open-source monitoring software that allows system administrators to monitor the health and performance of servers, applications, and network devices. Nagios provides a comprehensive solution for monitoring the IT infrastructure and can alert administrators of potential problems before they become critical. In this article, we will go over the steps to install Nagios on CentOS and Red Hat Enterprise Linux (RHEL) 9/8. These steps cover everything from downloading the software to configuring authentication for the Nagios web interface. By the end of this article, you will have a fully functional Nagios server that can be used to monitor…

Nagios is an open-source monitoring tool that is used to monitor hosts, services, and network devices. It provides real-time monitoring, alerting, and reporting capabilities to help you proactively identify and resolve issues in your IT environment. In this article, we will show you how to install Nagios Server on Ubuntu & Debian, including the prerequisites, installation process, and configuration steps. Nagios Server is the central component of the Nagios monitoring system. It collects data from remote hosts, services, and network devices, and displays the information in a web interface. Nagios Server can be installed on a variety of operating systems,…

Iptables is a powerful firewall tool that is commonly used on Linux systems to control incoming and outgoing network traffic. One of the most important features of iptables is its ability to log network activity, which can be used to troubleshoot issues and monitor security. However, many beginners may find the process of enabling logging in iptables confusing or overwhelming. Before we begin, it is important to note that iptables logging is only available in kernel 2.4.x and later versions. Also, you need to have root access to your Linux system to perform the steps outlined in this guide. This…

This article will help you to how to manage services using the systemctl command for Systemd services. Systemd is a system and service manager for Linux-based operating systems for managing services. Systemd is more powerful and getting more popularity over older SysVinit. Most of newer release of the Linux-based operating system (eg: CentOS/Redhat 7, Fedora 25, Ubuntu 16.04) using Systemd as a default service management tool. Before using the following example commands change <servicename> with your actual service name like httpd, mysql, apache2 or ssh. Start or Stop Service: Syntax: $ sudo systemctl start <servicename>.service $ sudo systemctl stop <servicename>.service…

Red Hat Enterprise Linux (RHEL) is a widely used and popular distribution of Linux, known for its stability and security. However, the default package repositories provided by Red Hat may not always include the latest software versions or additional software that you may need. This is where additional repositories such as the Remi and EPEL repositories come in. These repositories provide a wide range of additional software packages that can be easily installed on your system. In this article, we will go over a step-by-step guide on how to configure the REMI repositories on an RHEL-based system. Step 1: Install…