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How to Find and Kill Zombie Processes on Linux Systems

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In this mini post I’ll show you how to find and kill all zombie processes that may exist on your Linux Systems. First, we need to define What is the Zombie process? and Why it exists? A process is called a zombie process or defunct process if the process has beenRead More

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Howto remove/resolve Openvpn message “KEY_CONFIG pointing to the wrong version of openssl.cnf” on Linux Systems

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In this mini post I’ll show you how to  solve this Openvpn error message “KEY_CONFIG pointing to the wrong version of openssl.cnf” which may appears when you try to Generate Keys and Certificates which needed in the installation process of OpenVPN server on Debian 9 “stretch” Linux systems. You canRead More

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Howto remove/resolve git message “Commit your changes or stash them before you can merge” on Linux Systems

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In this mini post I’ll show you how to  solve this git error message “Commit your changes or stash them before you can merge” which appears when you try to pull the latest code from your git repository and did some “not committed” modifications to your code/repository on your localRead More

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Howto reset AUTO_INCREMENT from a table in MySQL/MariaDB Databases

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In this post, I’ll show you how to reset the auto_increment field from a table in MySQL/MariaDB databases. Sometimes you need to drop all the data in an existing table and reset the auto_increment to start from 1. This post is dealing with only resetting the auto_increment to 1. ToRead More

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Howto delete a column from a table in MySQL/MariaDB Databases

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In this post, I’ll show you how to drop a column from a table in MySQL/MariaDB databases. Sometimes you need to drop a wrongly created column in your table, or sometimes when you deploy a rails application and there is a database migration, if the deploy fail for any reasonRead More

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How to Configure Static DNS on CentOS/Redhat/Fedora Linux Systems

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If you want to hard-code DNS servers to use on CentOS or Fedora, the method can differ, depending on whether you use Network Manager or network service. On RHEL based systems, Network Manager is used to manage network interfaces by default, while you can switch to network service. Configure staticRead More

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How to prevent a package from being updated in Debian/Ubuntu Linux Systems

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If you want to update all the packages other than one in your Debian server follow this procedure There are three ways of holding back packages, with dpkg, aptitude or with dselect. Option1: Using dpkg Put a package on hold echo “package hold” | dpkg –set-selections Example echo “apache2 hold”Read More

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How to Remove/Delete Old Kernel Images on Debian/Ubuntu Linux Systems

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Suddenly, my Ubuntu update failed, and after checking my machine, I found that /boot partition is full, which caused this issue. I noticed that old kernel still exists in my system. In this mini post, your will find the answer for these question on Debian/Ubuntu Linux systems: Why doesn’t UbuntuRead More

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What is the Differences between A Web Server and An App Server

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When you research how to deploy your Rails app, you’ll see a lot of names: Apache, Unicorn, Puma, Phusion Passenger, Nginx, Rainbows, and many more. They all seem to fit under the “deploying Rails” category of software, but there’s a key difference between them. Some are “web servers,” and othersRead More

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Howto switch to another ruby version (temporarily, per project, or globally) using rbenv

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As systems engineer, who setups and maintains different servers running Ruby On Rails applications ” testing, staging, and production servers”, I’ve many ruby versions installed on my machine and I’ve to switch between them when deploying new code of ROR apps to any of my servers. Why I’ve to switchRead More

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