Author: Rahul

A shell is a command line interpreter. Its a special program which takes input from standard input devices, convert it to machine language and send to OS. After processing by OS, send result back to shell. Shell again translate it to human readable format and send results to output devices. Linux Shells: Bash Shell ( Born Again Shell ) : This is most common shell used by linux now a days. Bash sell is developed by Sir Brian Fox and Chet Ramey. CSH ( C Shell ) : The C shell’s syntax and usage are very similar to the C…

The Ext3 and Ext4 filesystem includes support of ACLs on files and directories. ACL provides more control permissions on file than standard three access categories (owner, group, and other ). Using ACL you can provide permission to a specific user or group to file. Before working on ACL make sure that ACL is enabled on the mounted file system. You can enable it during mounting the filesystem with the ACL option. Use the following command Check if ACL is enabled on the filesystem or not. sudo mount Output /dev/mapper/VolGroup00-LogVol00 on / type ext3 (rw,noatime,acl) Enable ACL by remounting file system…

MySQL is a relational database management system, used for storing data in form of tables and records. You can insert, modify or retrieve data using SQL statements or programming languages. It allows us to create new users and grant permissions on tables of the database. As a good practice always use a separate user for all databases. This will ensure that the application can’t access other applications’ databases. The purpose of this tutorial is to create a new user in the MySQL server and grant permissions to databases. This tutorial includes instructions to create users, and grant permission on all…

Postfix is fast and popular SMTP server widely used. The main job of postfix is to relay mail locally or to the intended destination outside the network. Some of the most popular SMTP servers are Sendmail, Postfix, and Qmail. By default, Sendmail comes pre-installed with CentOS/RHEL 5. We will need to remove it and install Postfix. You may also like: Install Postfix on Ubuntu Step 1 – Install Postfix If Postfix not already installed on your machine, Install it using the following command. Also, remove sendmail if already installed. yum remove sendmail yum install postfix Make postfix as default MTA…

Securing specific URLs in Apache is essential to protect important parts of your website. This guide will help you do it step by step, even if you’re new to Apache. You’ll learn how to limit access to certain URLs to specific IP address or by setting up a login requirement. This means only people with the right username and password or accessing from specified IP address can see those parts of your site. By following these simple instructions, you can keep your website more secure and ensure that sensitive information is protected from unauthorized access. In this tutorial you will…

Sometimes SQL Server logs files acquire a large space on the disk. In that case, we need to reduce the size of the log file to claim some space. But truncating or reducing database log file in SQL Server 2008 can be quite difficult. It also has its own issues. This article contains a set of commands to Shrink Log Files of SQL Server database. Generally this command is I prefer to take a backup of the database before executing below command for a safer side Shrink SQL Server Transaction Log Files First of all, check the actual name of…

Linux provides a number of tools for network configuration. Most important network settings for you Linux machine to access over network are IP configuration Device activation DNS configuration Default gateway 1. Default Network Configuration Files: Default linux interfaces configuration file exists in /etc/sysconfig/network-scripts/ named ifcfg-ethX ( ‘X’ is replace with number 0,1 or 2 etc ). /etc/sysconfig/network : is global configuration file NETWORKING = yes HOSTNAME = server1.tecadmin.net GATEWAY = 192.168.10.1 /etc/sysconfig/network-script/ifcfg-ethX : is Ethernet configuration file so assign ip address, netmask on interface. /etc/resolv.conf : DNS servers ip addresses are specified in this file. /etc/hosts : Is used for…

Packaging software into RPM (Red Hat Package Manager) format is an essential skill for developers and system administrators working with Red Hat-based Linux distributions such as CentOS and RedHat. RPMs allow for easy installation, upgrade, and removal of software, ensuring that applications can be distributed and managed efficiently. This guide will walk you through the process of packaging your script into an RPM, step by step. Prerequisites Before we begin, ensure you have the following: A CentOS or RedHat system for packaging and testing. Your script that you wish to package. rpm-build and rpmdevtools packages installed. You can install them…

Using HAProxy, you can construct high-availability systems and HAProxy stats provide detailed statics. It can be used with popular servers like Apache, Tomcat, NGINX, and others. This post describes how to enable HAProxy statistics on your machine. After you have configured and installed HAProxy on your system, you may monitor its statistics to determine its current performance. With HAProxy Stats, you can view information about the number of connections, data transfer, server status, and more. Because it is browser-based, you can use a web browser to get real-time information about your HAProxy implementation. In this article, we delineate how to…

Sometimes we need to insert a line at middle of the existing file. You can add line at specific line number using Linux command line or shell scripts. In this tutorial, we will discuss about adding a text line at middle of file as specific line number. Let’s have an example, I have a text file named file1.txt with following content: cat file1.txt this is line one this is line two this is line three Now I have to insert text “HelloWorld” at the line number 3. To do this run the following command. sed -i ‘3iHelloWorld’ file1.txt Details of…