Migration Guide: CentOS to AlmaLinux, Rocky Linux and Other Alternatives

CentOS 8 Reached End-of-Life on December 31, 2021

With Red Hat officially ending support for CentOS 8, users are forced to migrate to a different operating system. While CentOS 7 remains supported till end of 2024, the life cycle of the newer CentOS 8 was cut short by Red Hat for the end of 2021. Red Hat’s decision to end the CentOS 8 support remains highly controversial in the Linux community and it has stirred a lot of criticism. While the EOL of CentoOS 8 is a fact, we’re going to focus on recommending reasonable alternatives that can swiftly replace no longer supported CentOS 8.

Alternatives to CentOS 8

If your server runs CentOS, then the natural solution seems to migrate to other distribution based on Red Hat Enterprise Linux (RHEL) code. Migrating to one of the recommended RHEL derivatives will ensure a seamless experience and uninterrupted performance regardless of what you run on the server. We describe 4 RHEL derivatives in this article:

• AlmaLinux
• Rocky Linux
• Oracle Linux
• CentOS Stream

All of them aim to be 100% binary compatible with the original CentOS, meaning your current projects running on CentOS should run on each of them in the same way. From a technical perspective and from user’s experience, there is not much of a difference between the original CentOS 8 and the above-mentioned distributions.

The decision on which distribution to migrate is less about the functionality of the operating system and more about how it’s developed and maintained. Some of the alternatives are free community projects, while others are backed by large-scale commercial businesses.


First distribution we will cover is AlmaLinux, an increasingly popular semi-commercial project.

AlmaLinux is developed as a direct successor for CentOS. It is the binary equivalent to CentOS 8. But unlike Rocky Linux, the development is run by a private company. CloudLinux is a company that founded and funded the AlmaLinux OS foundation. CloudLinux invested approximately $1 million to develop AlmaLinux, after Red Hat announced discontinued support for CentOS 8. The combination of private funding and a strong community makes this distribution very promising.

This distribution is widely recognized in the IT community. For example, cPanel, developers of a popular server management panel, decided to support AlmaLinux from day one. And so did Plesk. The endorsement from both well-known panels’ developers is not only a matter of reputation, but it also guarantees easy migration for all users working with these panels.

Key features:

  • Backed by a reputable company
  • Active community
  • Works with cPanel and Plesk

Rocky Linux

When Red Hat announced the end of support for CentOS 8, one of the co-founders of the original CentOS operating system stepped in. Henry Kurtzer founded CentOS together with his colleague Rocky McGaugh in 2004. When Kurtzer decided to start working on a new substitute for CentOS, he named the new operating system after the late Rocky McGaugh. As all other alternatives mentioned in this article, the Rocky Linux distribution is based on the RHEL code, which means there are only marginal differences in code in comparison to CentOS.

Rocky Linux is an independent project with a free community support. The stable release 8.4 was released in June 2021 under the codename “Green Obsidian”. From all mentioned distributions, this is the youngest distribution, and one that is still under construction.

Since mid-2021, Henry Kurtzer has been offering paid support plans via his CIQ company, trying to offer “enterprise-grade” services . Still, the Rocky Linux distribution is at heart a community project preserving the original open-source spirit.

Key features:

  • Active community
  • Lead by CentOS founder
  • Slower release cycle
  • Young project
  • Plesk / cPanel support is missing

CentOS Stream

CentOS Stream is an alternative to CentOS 8 that comes directly from Red Hat. The main difference is that it has a different release cycle than other CentOS8 alternatives. It’s a rolling release of the RHEL, meaning that there are almost constant updates with all the newest developments in the code of the core, libraries and applications:

On one hand this means access to the newest software very quickly, on the other hand there is a higher risk of compatibility issues. It is a great idea for a development sandbox, but not necessarily for a production system.

Key features:

  • Backed by a renowned company
  • Constantly Updated

Oracle Linux

One of the less mentioned alternatives is using Linux from Oracle. Like all other alternatives, Oracle’s Linux is 100 percent binary compatible with the original Red Hat distribution. And that makes it also very close to the CentOS distribution – Oracle ensures that their Linux is fully compatible with existing CentOS 8 apps.

The biggest advantage of Oracle Linux is obvious – the support of one of the most prominent IT companies. The customer support isn’t free, but everything else is. Some users also consider as an advantage the possibility to perform updates via the yum server.

On the other hand, many users are now discouraged from using Linux distributions developed by corporations. They argue that after Red Hat discontinued support of CentOS, Oracle Linux can end up doing the same. But at least for now, the Oracle Linux remains a perfectly viable alternative, especially if you can afford their support.

Key Features:

  • Backed by a renowned company

Contabo Recommendation

All distributions mentioned above are very close to the original CentOS 8. Developers of all mentioned distributions also made it easy to migrate using just a few commands.

Your decision which alternative to use should be based on who stands behind each project. Do you trust an open community like Rocky Linux or are you more keen on projects backed by big corporations like Oracle?

If we were to recommend just one distribution, it would undoubtedly be AlmaLinux. It has the stability thanks to the backing of CloudLinux and the energy coming from the community. That’s why we recommend AlmaLinux as a safe bet for CentOS 8 users.

How to Migrate from CentOS 8

Video Guide

Below, you will find a brief description of the migration process for AlmaLinux, Rocky Linux, CentOS Stream and Oracle Linux.

Don’t forget to back up your data before performing the migration. If you don’t care about the data on the instance, you can simply reinstall the virtual machine without performing a migration. Contabo customers can do this in Contabo Customer Panel and choose AlmaLinux, Rocky Linux or CentOS Stream.

First, log in to your instance using SSH. Also, please make sure you have sufficient admin rights first. The easiest way how to avoid admin rights issues is to enter the command sudo -i at the beginning of each session:
sudo -i

How to migrate from CentOS 8 to AlmaLinux

Before migrating, update your current distribution by running this command:
dnf update

Download the distribution from GitHub using
curl -O https://raw.githubusercontent.com/AlmaLinux/almalinux-deploy/master/almalinux-deploy.sh

Assign all necessary permissions to the script:
chmod +x almalinux-deploy.sh

Now run the script by typing

And finally

How to migrate from CentOS 8 to Rocky Linux

Before migrating, update your current distribution by running this command:
dnf update

Rocky Linux developers have created a script called migrate2rocky. To obtain the distribution, just download it using this command:
curl -O https://raw.githubusercontent.com/rocky-linux/rocky-tools/main/migrate2rocky/migrate2rocky.sh

When the file has been finished downloading, give the script all necessary permissions by
chmod u+x migrate2rocky.sh

Now execute the script itself:
./migrate2rocky.sh -r

And finally

How to migrate from CentOS 8 to CentOS Stream

Before migrating, update your current distribution by running this command:
dnf update

Start the installation by typing:
dnf install centos-release-stream

After the installation is done, you have to change the repository for CentOS Stream:
dnf swap centos-linux-repos centos-stream-repos

And at last, let’s sync all your existing packages with the new distribution:
dnf distro-sync

and finally

How to Migrate From CentOS 8 to Oracle Linux

Before migrating, update your current distribution by running this command:
dnf update

Download the distribution from GitHub:
curl -O https://raw.githubusercontent.com/oracle/centos2ol/main/centos2ol.sh

Now run this command to replace your CentOS 8 with the Oracle:

And finally

How To Set Up Automatic Deployment with Git with a VPS


For an introduction to Git and how to install, please refer to the introduction tutorial.

This article will teach you how to use Git when you want to deploy your application. While there are many ways to use Git to deploy our application, this tutorial will focus on the one that is most straightforward. I assume you already know how to create and use a repository on your local machine. If not, please refer to this tutorial.

When you use Git, the workflow generally is toward version control only. You have a local repository where you work and a remote repository where you keep everything in sync and can work with a team and different machines. But you can also use Git to move your application to production.

Server Setup

Our fictitious workspace:

Your server live directory: /var/www/html

Your server repository: /var/www/site.git

What should we do if we want to push to site.git and at the same time make all the content available at /var/www/html?

To create our repository:

On /var/www/site.git we execute sudo git config –global init.defaultBranch main and right after sudo git init –bare

You will see a few files and folders, including the ‘hooks’ folder. So let’s go to ‘hooks’ folder:

cd hooks

sudo touch post-receive
sudo nano post-receive

git –work-tree=/var/www/html –git-dir=/var/www/site.git checkout –force

sudo chmod +x post-receive


git remote add production ssh://root@ip-address/var/www/site.git


(take ownership)———————————

sudo chown -R useranme /var/www/repo

(change permissions) —————————

sudo chmod -R 775 /var/www/repo

Setting up a WordPress cluster for huge sites

If you have a huge site, chances are you also do a lot of data processing – imports, exports, calculations etc.

These kind of batch processing jobs that max out the CPU and disk are the mortal enemy of real-time transactions. Your web visitors demand real-time interaction and fast response from your site, so if you are running imports and maxing out your CPU and disk on the same server hosting your web traffic then your users are regularly going to encounter slowness. This leads to loss of interest from your visitors, loss of sales and loss of SEO rank.

Ultimately, to solve this, once you have exhausted scaling up, you need to architect a better solution.

Scaling Up WordPress – check before building your cluster!

If you are considering building a cluster, it means you think you can’t get more speed from a single server. If you have not yet used our Super Speedy Pack yet then you should definitely try that before building a cluster. We built our Super Speedy Pack to solve search, filtering and underlying scalability issues exhibited in WordPress and WooCommerce.

It is not uncommon for customers with large sites to get 10x or more speed boost from our Super Speedy Plugin pack so prior to building your cluster, check out our Super Speedy Plugin pack.

Scaling Out with a WordPress Cluster

You need to separate the batch processing from the realtime stuff. That means you need a minimum of 2 servers. 1 server processes all the data imports, exports, calculations, category counts, etc – the data is replicated to the 2nd server and that server serves your web traffic.

If you’re going to the bother of getting 2 servers, you’re better off going further and getting 3 servers. It’s very little extra hassle and then gives you the ability to have 3 servers online at once with no batch processing, or 1 or 2 of the servers handling batch processing and the remaining ones serving web traffic.

Using this model, you can also easily switch servers offline to upgrade them without interrupting visitors to your website. That means you can be online 100% of the time!

Note that this setup technically uses 4 servers – the 4th server being a load balancer. Instead of this server, you could use the Digital Ocean load balancer feature/server instead but I provide details below for installing this easily.

If you’re looking at building a cluster for more speed, you may find our plugin pack will help give you the speed boost you need.

Step by step guide to building your cluster

This is the guide I use to install these clusters, so hopefully it helps some of you out there who wish to go huge with your WordPress sites.

Create 3 Ubuntu 16.04 servers

I like Digital Ocean, so this guide is using their hosting, but you can use any host provided they offer private networking and Ubuntu 16.04.

Create 3 Ubuntu 16.04 (or 3 servers on any platform) – they make it easy to make multiple at once – make sure to enable private networking and add your ssh key.

Install PerconaDB XtraDB Cluster on your cluster-nodes

Log into your 3 droplets and run the following commands on each node:

wget https://repo.percona.com/apt/percona-release_0.1-4.$(lsb_release -sc)_all.deb
dpkg -i percona-release_0.1-4.$(lsb_release -sc)_all.deb
apt-get update
apt-get upgrade
apt-get install percona-xtradb-cluster-57

Note: You will be asked to enter a new root password for the cluster. To make life easier, use the same password for each PerconaDB node, or leave the root password blank and it will infer security if you log in as root and connect.

Configure private networking

We want the nodes to share data over the private network, rather than out and in from your hosting company. This prevents crazy bandwidth costs, speeds things up and improves security.

Even though private networking is already enabled, we need to be able to reliably use eth1 (rather than eth0) as the private network device.

On each node edit the grub networking file. I prefer vi to edit files, but you can use nano or even edit the files with Filezilla.

vi /etc/default/grub.d/50-cloudimg-settings.cfg

Find the line that begins GRUB_CMDLINE_LINUX_DEFAULT and alter it as follows (add net.ifnames=0):

GRUB_CMDLINE_LINUX_DEFAULT="console=tty1 console=ttyS0 net.ifnames=0"

Save the file then run the update grub command and reboot (only time I know of where you need to reboot a linux box!).

shutdown -r now

Repeat the above for all your nodes. Then you can check config with this:

ifconfig -a

You should see the public IP address against eth0 and the private address against eth1.

You can also view each ethernet devices configuration here:

cat /etc/network/interfaces.d/50-cloud-init.cfg

The file above will already be configured if you selected private networking when you created the droplet.

Take a note of the private IP address for each of your 3 nodes. This information is also available from your Digital Ocean interface when you click through to each droplet.

You can test private networking is working by pinging the private IP address of another node from one of the nodes:


Configure replication

Firstly, we need a replication user. Create this user on all 3 nodes.

Log into mysql:


or if you chose a password for your mysql server earlier, use this:

mysql -u root -p

Enter the root DB password you chose earlier then create a new user for replication purposes (choose a strong password and note it down so we can add it to the configuration files):

CREATE USER 'sstuser'@'localhost' IDENTIFIED BY 'password';

Next exit MySQL by typing ‘exit’ then hitting enter, then stop MySQL on all 3 nodes using:

service mysql stop

On node1, customise the configuration file below according to your private IP addresses and replication user password enter it into this file:

vi /etc/mysql/percona-xtradb-cluster.conf.d/wsrep.cnf
  1. Enter the 3 private IP addresses for wsrep_cluster_address, separated by commas.
  2. Enter node 1 private IP address for  wsrep_node_address.
  3. Enter the sst password for wsrep_sst_auth.
  4. Change the name of the node on the line wsrep_node_name

Your file will end up looking something like this (lines in bold are the lines you need to alter from the default config):

# Path to Galera library

# Cluster connection URL contains IPs of nodes
#If no IP is found, this implies that a new cluster needs to be created,
#in order to do that you need to bootstrap this node

# In order for Galera to work correctly binlog format should be ROW

# MyISAM storage engine has only experimental support

# Slave thread to use
wsrep_slave_threads= 8

# This changes how InnoDB autoincrement locks are managed and is a requirement for Galera

# Node IP address
# Cluster name

#If wsrep_node_name is not specified, then system hostname will be used

#pxc_strict_mode allowed values: DISABLED,PERMISSIVE,ENFORCING,MASTER

# SST method

#Authentication for SST method

Note: You will also need to remove the # comment from the beginning of the lines with the wsrep_node_address and the wsrep_sst_auth.

Copy the contents of the file and then save it. Configure node 2 and node 3 by editing the same file on those nodes and altering 2 rows from the file above:

  1. Change wsrep_node_address to be the private IP address of node 2 (or node 3 for that node)
  2. Change wsrep_node_name to pxc-cluster-node-2 or pxc-cluster-node-3

Once you’ve done this, you’re ready to bootstrap your cluster.

Bootstrap your cluster

On node 1, run the following command:

/etc/init.d/mysql bootstrap-pxc

Check it’s running by logging into mysql and running this command:

show status like 'wsrep%';

Note: The above command can be useful in future to check for replication status – you can see things like how many items are queued to be replicated amongst other details.

On node 2 and 3, run the following:

/etc/init.d/mysql start

You now have a Percona cluster with 3 nodes replicating data to each other.

Install Nginx and PHP 7 on all 3 nodes

On each node, install Nginx and PHP 7 using the following sequence of commands:

apt-get install nginx
apt-get install php7.0
apt-get install php7.0-curl 
apt-get install php7.0-gd 
apt-get install php7.0-intl 
apt-get install php7.0-mysql 
apt-get install php-memcached
apt-get install php7.0-mbstring
apt-get install php7.0-zip
apt-get install php7.0-xml
apt-get install php7.0-mcrypt
apt-get install unzip

A faster way to run all of the above would be using this single line:

apt-get install -y nginx php7.0 php7.0-curl php7.0-gd php7.0-intl php7.0-mysql php-memcached php7.0-mbstring php7.0-zip php7.0-xml php7.0-mcrypt unzip


Install Unison for file replication

After much testing, GlusterFS is not well-suited to WordPress file-replication. GlusterFS slows down a LOT when there are a lot of files in each directory. The guide has been updated to use Unison instead. This Unison setup uses a star schema for file replication, with node 1 at the centre of the star.

node 1 <--> node 2 file replication	
node 1 <--> node 3 file replication

That means a file edit on node 3 will replicate to node 1 and then to node 2. A file edit on node 1 will replicate out directly to node 2 and 3. Because of this, it makes sense to make node 1 our wp-admin server where we upload plugin files. Because of this star schema for file replication, node 1 is your most important node. If it goes down, or you switch it off, file replication will be paused until you bring it back online.

On each node, install unison:

apt-get -y install unison openssh-server

This will allow us to run the replication commands later once we have installed the WordPress files.

Configure SSH so nodes can connect to each other

SSH access is required for Unison to be able to replicate files. Run the following on all 3 nodes:


Hit enter 3 times to accept 3 defaults inc 2 blank passwords for the keyfile so it works non-interactively
Now, grab a copy of the id_rsa.pub files for each node and paste them into the other 2 nodes authorized_keys file. Find the public keys of each node by running this command:

cat /root/.ssh/id_rsa.pub

Then paste those public keys into the authorized_keys file of the other 2 nodes:

vi /root/.ssh/authorized_keys

Authenticate each node

On node 1, run:

ssh ipofnode2
ssh ipofnode3

You will be asked if you wish to trust the other node. Answer yes.

Repeat this on node 2 and node 3, connecting to the other 2 nodes.

Replicate the web folder files using Unison

Now that we have ssh authentication, we can set up Unison to replicate the website files to node 2 and 3. Run the following commands on node 1 of your cluster:

unison /var/www ssh:// -owner -group	
unison /var/www ssh:// -owner -group

Note: replace the IP addresses with your own and the folder names with your own.

Since you have no files yet in /var/www these commands will complete quickly.

Now set up a crontab/cron job for Unison. Run the following command:

crontab -e

Choose whatever editor you prefer when it asks you then append the following to the end of the file:

* * * * * unison -batch /var/www ssh:// &> /dev/null	
* * * * * unison -batch /var/www ssh:// &> /dev/null

Change IP addresses and folder locations. Use internal IP addresses so traffic goes over the faster internal network card.

Install WordPress files onto Node 1 only

Because we are using file replication and we already have database replication in our cluster, we only need to install WordPress onto node 1. On node 1, run the following:

wget https://wordpress.org/latest.zip -P /var/www/
unzip /var/www/latest.zip -d /var/www/
mv /var/www/wordpress /var/www/wpicluster
chown www-data:www-data /var/www/wpicluster -R
rm /var/www/latest.zip

Note: Instead of /var/www/wpicluster you could use /var/www/yourdomain.com but if you do, ensure you alter the nginx config files in the next section.

Configure Nginx to load your WordPress site on each node

I’ve created some configuration files to make this part quicker and easier. The configuration files set Nginx up to work over port 80 – later, we will add SSL to our load balancer. This reduces load on our servers since they won’t have to decrypt SSL traffic.

The configuration files here also configure the Nginx fastcgi-cache, so you don’t need to install Varnish. They’re also domain-name independent, so no configuration required.

On all 3 nodes, run the following commands:

git clone https://github.com/dhilditch/wordpress-cluster /root/wordpress-cluster/
cp /root/wordpress-cluster/etc/nginx/* -R /etc/nginx/
ln -s /etc/nginx/sites-available/wpintense.cluster.conf /etc/nginx/sites-enabled/
mkdir /sites/wpicluster/cache -p
service nginx restart

Set up your Load Balancer

Digital Ocean provide a load balancer, but with that approach you have to manually renew your SSL certificates. Plus you get less control – we want control so we can send wp-admin traffic to node 1. So follow the instructions below to set up your own load balancer.

First, create a droplet with Ubuntu 16.04 again, private networking and your SSH keys.

Then log onto your load balancer droplet and run the following commands:

add-apt-repository ppa:nginx/stable
apt-get update
apt-get install nginx

Then create a new file at /etc/nginx/conf.d/loadbalancer.conf.

vi /etc/nginx/conf.d/loadbalancer.conf

This will automatically be loaded when you restart nginx. Enter the following in the file, adjusted for your private IP addresses.

upstream clusterwpadmin {
upstream clusternodes {
 server max_fails=3; 
 server max_fails=3;
server {
     listen 80;
# this block is for letsencrypt
 root /var/www/html;
 location ~ /.well-known {
      allow all;
  try_files $uri $uri/ =404;
 server_name _;
 #return 301 https://$host$request_uri;
 location ~ /wp-(admin/|login\.php\b|cron\.php) {
     proxy_pass http://clusterwpadmin;
 proxy_set_header X-Forwarded-Host $host;
 proxy_set_header X-Forwarded-Server $host;
 proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
 proxy_set_header X-Forwarded-Proto $scheme;
 proxy_set_header X-Real-IP $remote_addr;
 proxy_set_header Host $host;
location / {
     proxy_pass http://clusternodes;
 proxy_set_header X-Forwarded-Host $host;
 proxy_set_header X-Forwarded-Server $host;
 proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
 proxy_set_header X-Forwarded-Proto $scheme;
 proxy_set_header X-Real-IP $remote_addr;
 proxy_set_header Host $host;
server {
     listen 443 ssl;
 #ssl_certificate /etc/letsencrypt/live/yourdomain.com/cert.pem;
 #ssl_certificate_key /etc/letsencrypt/live/yourdomain.com/privkey.pem;
location ~ /wp-(admin/|login\.php\b|cron\.php) { 
     proxy_pass http://clusterwpadmin; 
 proxy_set_header X-Forwarded-Host $host; 
 proxy_set_header X-Forwarded-Server $host; 
 proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; 
 proxy_set_header X-Forwarded-Proto $scheme; 
 proxy_set_header X-Real-IP $remote_addr; 
 proxy_set_header Host $host; 
location / {
     proxy_pass http://clusternodes;
 proxy_set_header X-Forwarded-Host $host;
 proxy_set_header X-Forwarded-Server $host;
 proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
 proxy_set_header X-Forwarded-Proto $scheme;
 proxy_set_header X-Real-IP $remote_addr;
 proxy_set_header Host $host;
#if a user connects to yourdomain.com:9443 they will be directed to node 1. This is where admins should connect to add plugins etc.
server {
     listen 9443 ssl;
 server_name _;
 #ssl_certificate /etc/letsencrypt/live/yourdomain.com/cert.pem;
 #ssl_certificate_key /etc/letsencrypt/live/yourdomain.com/privkey.pem;
location / {
     proxy_pass http://clusterwpadmin;
 proxy_set_header X-Forwarded-Host $host;
 proxy_set_header X-Forwarded-Server $host;
 proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
 proxy_set_header X-Forwarded-Proto $scheme;
 proxy_set_header X-Real-IP $remote_addr;
 proxy_set_header Host $host;

Save that file then you can restart nginx using:
service nginx restart

SaveNow, log into your DNS provider and point your new domain name at the public IP address of your loadbalancer node.

Configure WordPress

Now that we have database and file replication set up, and a load balancer, we can go about starting the 5-minute install of WordPress.

On node 1, connect to mysql using:

mysql -p (or just mysql if no root password)

Note: you’ll be asked for your password, so paste it in – right-click in putty is paste, and it’ll look like nothing happened because it’s a password field, but it does paste.

create database wpicluster;
grant all privileges on wpicluster.* to wpi@localhost identified by 'CHOOSEASTRONGPASSWORD';

Visit the URL you chose earlier for your loadbalancer, e.g. http://www.yourdomain.com.

Choose your language, then enter the database name: wpicluster, the username: wpi and the password you chose in the GRANT command above.

Set up WordPress Cron on only node 1

WP Cron is awful. It relies on users visiting your site in order to run scheduled tasks. In this case, we don’t even want scheduled jobs running on node 2 or 3, so we’ll disable wp cron across all nodes and then implement a real cron job on node 1.

On node 1, edit /var/www/wpicluster/wp-config.php. This file edit will replicate to your other nodes.

vi /var/www/wpicluster/wp-config.php

and insert the following lines somewhere:

define('WP_DISABLE_CRON', true);
if (strpos($_SERVER['HTTP_X_FORWARDED_PROTO'], 'https') !== false) {

Note: Only the first line is to disable WP_CRON. The rest is for later when we forward traffic from our load balancer and we want to ensure WordPress knows to server up static files over HTTPS if that was what the user requested.

If you’re struggling to figure out where to put this code, you can stick it after the define(‘DB_NAME’, ….); line.

This wp-config.php update will replicate out to the other nodes using GlusterFS, so you don’t need to modify this on the other nodes.

Now run:

crontab -e

And add an extra line as follows:

* * * * * wget http://yourdomain.com:9443/wp-cron.php?doing_cron &> /dev/null

Set up SSL on your load balancer

Now get your free SSL certificates from LetsEncrypt. On your load balancer node, run the following:

add-apt-repository ppa:certbot/certbot
apt-get update
apt-get install certbot
certbot certonly --webroot --webroot-path=/var/www/html -d yourdomain.com -d www.yourdomain.com

You should get a note telling you CONGRATULATIONS.  It will also tell you the location the key files were saved to. Now edit the loadbalancer.conf file from earlier to set up SSL. (WordPress installation does not work well over SSL which is why we add SSL after installation)

vi /etc/nginx/conf.d/loadbalancer.conf

Uncomment the ssl_certificate (x2) and ssl_certificate_key (x2) lines and replace the path with the paths provided by the output from LetsEncrypt.

Also uncomment the line “return 301 https://$host$request_uri;”

service nginx restart

Once you have edited the loadbalancer.conf file and restarted nginx, you will have a working SSL certificate on your load balancer.

Note: At this point, if you access your website with https, some CSS will appear broken. There is one final stage we have to complete in order to fix this, which is almost the final step in the entire process.

Update your Site URL in WordPress

Log into node1.yourdomain.com. Visit the WordPress dashboard, then Settings->General.

You will see 2 domain entries, both of which are probably currently tied to your node 1 subdomain, and both of which will be http instead of https.

Replace both of these entries with https://www.yourdomain.com.

Note: Here you enter the domain name you chose for your load balancer, normally www.yourdomain.com or similar.

If you didn’t already, edit your wp-config.php file on Node 1 and just below where you disabled WP_CRON, add the following lines:

if (strpos($_SERVER['HTTP_X_FORWARDED_PROTO'], 'https') !== false) {

The traffic is being served over https to your users, but because it’s plain http on each node (between your load balancer and your nodes), you need to make sure WordPress knows it’s HTTPS so any static files are correctly loaded over HTTPS.

Go forth and conquer!

That’s it, a mammoth task complete.

You can visit wp-admin from any server, but you can also force traffic to node 1 for your own admin purposes by visiting https://www.yourdomain.com:9443/wp-admin/. With the configuration above, node 1 is never serving traffic to front-end users, so you can run all kinds of admin jobs on there without impacting slowing down user traffic.

If anyone has any questions, fire away!

Varnish Cache

sudo -i
apt update && apt upgrade
#Install Apache webserver
apt install apache2
systemctl start apache2
systemctl status apache2
#Being a webserver, Apache listens on port 80 by default. Use the netstat command as shown to verify this.
sudo netstat -pnltu
#Install Varnish HTTP Accelerator
apt install varnish
systemctl start varnish
systemctl status varnish
#Configuring Apache and Varnish HTTP Cache
nano /etc/apache2/ports.conf
listen to port 80 to 8080
nano /etc/apache2/sites-enabled/000-default.conf
listen to port 80 to 8080
systemctl restart apache2
#Setting up Varnish to listen to port 80
nano /etc/default/varnish
Scroll and locate the attribute ‘DAEMON_OPTS’. Be sure to change the port from 6081 to port 80
#If you check the /etc/varnish/default.vcl file, you should get the output shown below.
nano /etc/varnish/default.vcl
#Lastly, we need to edit the /lib/systemd/system/varnish.service and modify the port in ExecStart directive from port 6081 to 80.
nano /lib/systemd/system/varnish.service
Locate the ExecStart directive and change the port from port 6081 to 80.
systemctl restart apache2
systemctl daemon-reload
systemctl restart varnish
#Testing the Configuration
curl -I server_IP

CentOS 8: No URLs in mirrorlist error [How to Solve]


In CentOS 8, there is an error using yum. There is no URL in the image list, similar to the following:

Error: Failed to download metadata for repo 'appstream': Cannot prepare internal mirrorlist: No URLs in mirrorlist


On January 31, 2022, the CentOS team finally removed all packages of CentOS 8 from the official image.

CentOS 8 has expired on December 31, 2021, but the software package has been retained on the official image for some time. Now they are transferred to https://vault.centos.org


If you still need to run CentOS 8, you can run it in/etc/yum repos. Update the source in D. Use vault.centos.Org instead of mirror.centos.org.

sudo sed -i -e "s|mirrorlist=|#mirrorlist=|g" /etc/yum.repos.d/CentOS-*
sudo sed -i -e "s|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g" /etc/yum.repos.d/CentOS-*


Essentially, it replaces the previous URL with the URL that is still running. This problem should be solved within this period of time.

How to install MySQL server on CentOS 8 Linux

How do I install MySQL server 8.0 on CentOS 8 Linux server running on Linode and AWS cloud? How do I add and set up a new MySQL user and database account on the newly created CentOS server?

Oracle MySQL server version 8.0 is a free and open-source free database server. It is one of the most popular database system used in web apps and websites on the Internet.

Typically MySQL is part of the LAMP (Linux, Apache/Nginx, MySQL, Perl/Python/PHP) stack. Popular open-source software such as WordPress, MediaWiki, and others profoundly used by MySQL as a database storage engine. Let us see how to install MySQL server version 8.x on CentOS 8 Linux server.

How to install MySQL server on a CentOS 8

First, open the terminal app and then log in to your CentOS server using the ssh command:
$ ssh vivek@centos-8-ec2-box-ip
Now, update CentOS system to apply security updates and fixes on Linux system using the dnf command/yum command:
$ sudo yum update
## or ##
$ sudo dnf update

Sample outputs:

CentOS-8 - AppStream                            21 MB/s | 5.8 MB     00:00    
CentOS-8 - Base                                 14 MB/s | 2.2 MB     00:00    
CentOS-8 - Extras                               50 kB/s | 8.6 kB     00:00    
Dependencies resolved.
Nothing to do.

Step 1 – Installing MySQL 8 server

Luckily our CentOS 8 box comes with MySQL 8 server package. Let us search for it:
$ sudo yum search mysql-server
$ sudo yum module list mysql

And we see:

Last metadata expiration check: 0:02:47 ago on Mon Nov 23 16:26:31 2020.
===================== Name Exactly Matched: mysql-server ======================
mysql-server.x86_64 : The MySQL server and related files

Next, find out version information, run:
$ sudo yum info mysql-server
Here is what we see:

Last metadata expiration check: 0:02:22 ago on Mon Nov 23 16:26:31 2020.
Available Packages
Name         : mysql-server
Version      : 8.0.21
Release      : 1.module_el8.2.0+493+63b41e36
Architecture : x86_64
Size         : 22 M
Source       : mysql-8.0.21-1.module_el8.2.0+493+63b41e36.src.rpm
Repository   : AppStream
Summary      : The MySQL server and related files
URL          : http://www.mysql.com
License      : GPLv2 with exceptions and LGPLv2 and BSD
Description  : MySQL is a multi-user, multi-threaded SQL database server. MySQL
             : is a client/server implementation consisting of a server daemon
             : (mysqld) and many different client programs and libraries. This
             : package contains the MySQL server and some accompanying files
             : and directories.

Install it:
$ sudo yum install mysql-server

How to install MySQL 8 on CentOS 8 Linux

Click to enlarge

Step 2 – Enabling MySQL 8 mysqld.service,server

The service name is mysqld.service, and we need to enable it using the following systemctl command:
$ sudo systemctl enable mysqld.service
Confirmation displayed:

reated symlink /etc/systemd/system/multi-user.target.wants/mysqld.service → /usr/lib/systemd/system/mysqld.service.

Start the service and then verify it:
$ sudo systemctl start mysqld.service
$ sudo systemctl status mysqld.service

 mysqld.service - MySQL 8.0 database server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running) since Mon 2020-11-23 16:50:14 UTC; 4s ago
  Process: 551 ExecStopPost=/usr/libexec/mysql-wait-stop (code=exited, status=0/SUCCESS)
  Process: 681 ExecStartPost=/usr/libexec/mysql-check-upgrade (code=exited, status=0/SUCCESS)
  Process: 601 ExecStartPre=/usr/libexec/mysql-prepare-db-dir mysqld.service (code=exited, status=0/SUCCESS)
  Process: 577 ExecStartPre=/usr/libexec/mysql-check-socket (code=exited, status=0/SUCCESS)
 Main PID: 637 (mysqld)
   Status: "Server is operational"
    Tasks: 39 (limit: 24960)
   Memory: 331.0M
   CGroup: /system.slice/mysqld.service
           └─637 /usr/libexec/mysqld --basedir=/usr

Nov 23 16:50:13 centos-aws-mysql systemd[1]: Stopped MySQL 8.0 database server.
Nov 23 16:50:13 centos-aws-mysql systemd[1]: Starting MySQL 8.0 database server...
Nov 23 16:50:14 centos-aws-mysql systemd[1]: Started MySQL 8.0 database server.

Step 3 – Securing MySQL 8 server

All you need to do is type the following command, and it will secure MySQL 8 server installation on CentOS Linux:
$ sudo mysql_secure_installation

Please set the password for root here.

New password: 

Re-enter new password: 

Estimated strength of the password: 100 
Do you wish to continue with the password provided?(Press y|Y for Yes, any other key for No) : y
By default, a MySQL installation has an anonymous user,
allowing anyone to log into MySQL without having to have
a user account created for them. This is intended only for
testing, and to make the installation go a bit smoother.
You should remove them before moving into a production

Remove anonymous users? (Press y|Y for Yes, any other key for No) : y

Normally, root should only be allowed to connect from
'localhost'. This ensures that someone cannot guess at
the root password from the network.

Disallow root login remotely? (Press y|Y for Yes, any other key for No) : y

By default, MySQL comes with a database named 'test' that
anyone can access. This is also intended only for testing,
and should be removed before moving into a production

Remove test database and access to it? (Press y|Y for Yes, any other key for No) : y
 - Dropping test database...

 - Removing privileges on test database...

Reloading the privilege tables will ensure that all changes
made so far will take effect immediately.

Reload privilege tables now? (Press y|Y for Yes, any other key for No) : y

All done! 

Step 4 – Starting/Stopping/Restarting MySQL 8 server

The syntax is:
$ sudo systemctl start mysql.service
$ sudo systemctl stop mysql.service
$ sudo systemctl restart mysql.service

To view the MySQL 8 service log as follows using the journalctl command:
$ sudo journalctl -u mysqld.service -xe
$ sudo tail -f /var/log/mysql/mysqld.log

MySQL 8 log file sample entries:

2020-11-23T16:55:19.101316Z 0 [System] [MY-013172] [Server] Received SHUTDOWN from user . Shutting down mysqld (Version: 8.0.21).
2020-11-23T16:55:21.728819Z 0 [Warning] [MY-010909] [Server] /usr/libexec/mysqld: Forcing close of thread 10  user: 'root'.
2020-11-23T16:55:23.083389Z 0 [System] [MY-010910] [Server] /usr/libexec/mysqld: Shutdown complete (mysqld 8.0.21)  Source distribution.
2020-11-23T16:56:19.225544Z 0 [System] [MY-010116] [Server] /usr/libexec/mysqld (mysqld 8.0.21) starting as process 524
2020-11-23T16:56:19.237500Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2020-11-23T16:56:19.562441Z 1 [System] [MY-013577] [InnoDB] InnoDB initialization has ended.
2020-11-23T16:56:19.677202Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Bind-address: '::' port: 33060, socket: /var/lib/mysql/mysqlx.sock
2020-11-23T16:56:19.754024Z 0 [Warning] [MY-010068] [Server] CA certificate ca.pem is self signed.
2020-11-23T16:56:19.754207Z 0 [System] [MY-013602] [Server] Channel mysql_main configured to support TLS. Encrypted connections are now supported for this channel.
2020-11-23T16:56:19.780843Z 0 [System] [MY-010931] [Server] /usr/libexec/mysqld: ready for connections. Version: '8.0.21'  socket: '/var/lib/mysql/mysql.sock'  port: 3306  Source distribution.

Step 5 – Testing MySQL 8 installation

So far, so good. You learned how to install, set up, secure, and start/stop the MySQL 8 on CentOS 8 Linux cloud server. It is time to log in as a
mysql root user. The syntax is:
$ mysql -u root -p
$ mysql -u USER -h host -p
$ mysql -u USER -h host -p mysql

Let us type a few SQL commands at the mysql> prompt:

Testing MySQL on CentOS 8

Step 6 – Creating a new MySQL 8 database and user account with password

Let create a new database called ‘spacedb‘, type at the mysql> prompt:
Next, we are going to create a new user named ‘mars‘ for our database called ‘spacedb’ as follows:
CREATE USER 'mars'@'%' IDENTIFIED BY 'User_Password_Here';
Finally, give permissions:
Of course, we can grant ALL PRIVILEGES too as follows:
GRANT ALL PRIVILEGES ON spacedb.* TO 'mars'@'%';
See MySQL 8 users and their grants/permissions as follows:
SELECT user,host FROM mysql.user;
SHOW GRANTS for mars;

Test new user settings and DB as follows:
mysql -u mars -p spacedb
mysql -u mars -h localhost -p spacedb

Creating MySQL 8 database with user and password on CentOS 8


  • -u mars; : User name for login
  • -h localhost : Connect to server named localhost
  • -p : Prompt for password
  • spacedb : Connect to database named spacedb

Step 7 – Configuring MySQL 8 server on a CentOS 8

Let us see default config file using the cat command:
# cat /etc/my.cnf.d/mysql-server.cnf


Want to allow remote connections to your MySQL server? Edit the /etc/my.cnf.d/mysql-server.cnf and append the following line under [mysqld]:
bind_address =

WARNING: See MySQL documentation for a detailed explanation for tuning options as to each server and set up is unique. Do not set up values blindly. I provide them as a starting point for optimizing MySQL 8 installation and values depending upon available RAM, CPU cores, server load and other circumstances.

Set InnoDB settings:

default_storage_engine          = InnoDB
innodb_buffer_pool_instances    = 1
innodb_buffer_pool_size         = 512M
innodb_file_per_table           = 1
innodb_flush_log_at_trx_commit  = 0
innodb_flush_method             = O_DIRECT
innodb_log_buffer_size          = 16M
innodb_log_file_size            = 512M
innodb_stats_on_metadata        = 0
innodb_read_io_threads          = 64
innodb_write_io_threads         = 64

MyISAM settings:

key_buffer_size                 = 32M   
low_priority_updates            = 1
concurrent_insert               = 2
max_connections                 = 100   
back_log                        = 512
thread_cache_size               = 100
thread_stack                    = 192K
interactive_timeout             = 180
wait_timeout                    = 180

Buffer settings UPD:

join_buffer_size                = 4M    
read_buffer_size                = 3M    
read_rnd_buffer_size            = 4M    
sort_buffer_size                = 4M

Edit and config logging if needed (by default slow_query disabled):

log_queries_not_using_indexes   = 1
long_query_time                 = 5
#slow_query_log                  = 0     
#slow_query_log_file             = /var/log/mysql/mysql_slow.log

This is useful for mysqldump command to make backups:

max_allowed_packet              = 64M

Step 8 – Firewall configuration to open MySQL server TCP port 3306

Are you using MySQL 8 server remotely? Do you have Apache/Nginx/PHP/Python/Perl app on another server? Then open port for everyone:
$ sudo firewall-cmd --zone=public --add-service=mysql --permanent
Only allow access from CIDR:
$ sudo firewall-cmd \
--add-rich-rule 'rule family="ipv4" \
source address="" \
service name="mysql" accept' --permanent

The above is fine grained firewalld access rules to restrict access to MySQL 8 server to VLAN users only. See how to set up a firewall using FirewallD on CentOS 8 Linux for more info.


And there you have it, Oracle MySQL server version 8.x set up and running correctly on a CentOS Linux 8 server with Firewalld config. Further, you learned how to add a new database, user, and password for your project including MySQL 8 server tuning options.

Install Oracle Database 19c on CentOS 8 in VirtualBox

** Please use the root user to edit the files and execute the commands unless further notice. **


  1. Install the latest VirtualBox Platform Package and the VirtualBox Extension Pack (Oracle_VM_VirtualBox_Extension_Pack-VERSION.vbox-extpack).
  2. Download the latest VirtualBox Guest Additions (VBoxGuestAdditions_VERSION.iso).
  3. Download the latest CentOS Stream 8.
  4. Create a new virtual machine and install the CentOS to the virtual machine. During the CentOS installation, select Workstation as Base Environment, select Container ManagementDevelopment Tools and Graphical Administration Tools as Additional software for Selected Environment. Use http://mirror.centos.org/centos/8/BaseOS/x86_64/os/ as the installation source.
  5. After installing the CentOS, execute the following commands to get the required libraries to create applications for handling compiled objects.
dnf update
dnf -y install elfutils-libelf-devel
  1. Insert the ISO of VirtualBox Guest Additions to the virtual machine, and then install it.

Download Packages and Software

Hostname and Host File

  1. Open the file /etc/hostname, change the content to update the hostname.
  1. Open the file /etc/hosts, add your IP address and hostname. ol8-19.localdomain

Install Required Packages

  1. Perform a dnf update to update every currently installed package.
dnf update
  1. Add execute permission to the downloaded rpm files.
chmod u+x *.rpm
  1. Install the libcapl library for getting and setting POSIX.1e (formerly POSIX 6) draft 15 capabilities.
dnf localinstall -y compat-libcap1-1.10-7.el7.x86_64.rpm
  1. Inatll the libstdc++ package which contains compatibility standard C++ library from GCC 3.3.4.
dnf localinstall -y compat-libstdc++-33-3.2.3-72.el7.x86_64.rpm
  1. Install the below required packages.
dnf install -y bc binutils elfutils-libelf elfutils-libelf-devel fontconfig-devel \
    gcc gcc-c++ glibc glibc-devel ksh ksh libaio libaio-devel libgcc libnsl libnsl.i686 \
    libnsl2 libnsl2.i686 librdmacm-devel libstdc++ libstdc++-devel libX11 libXau libxcb \
    libXi libXrender libXrender-devel libXtst make net-tools nfs-utils smartmontools \
    sysstat targetcli unixODBC;

Install Oracle Installation Prerequisites

  1. Install the Oracle Installation Prerequisites (OIP) package.
dnf localinstall -y oracle-database-preinstall-19c-1.0-1.el7.x86_64.rpm
  1. Open the /etc/group file, update the GID of the below items.
  1. Open the /etc/passwd file, update both the UID and GID of account oracle.
  1. Update the password of account oracle.
passwd oracle
  1. Set secure Linux to permissive by editing the /etc/selinux/config file.
  1. Set the secure Linux change right now.
setenforce Permissive
  1. Disable the firewall.
systemctl stop firewalld
systemctl disable firewalld

Setup Oracle User Profile

  1. Create Oracle directories.
mkdir -p /u01/app/oracle/product/19.3.0/dbhome_1
mkdir -p /u02/oradata
chown -R oracle:oinstall /u01 /u02
chmod -R 775 /u01 /u02
  1. Create a new directory for Oracle user.
mkdir -p /home/oracle/scripts
chown -R oracle:oinstall /home/oracle
  1. Create an environment setting file.
cat > /home/oracle/scripts/setEnv.sh <<EOF
# Oracle Settings
export TMP=/tmp
export TMPDIR=\$TMP

export ORACLE_UNQNAME=cdb1
export ORACLE_BASE=/u01/app/oracle
export ORACLE_HOME=\$ORACLE_BASE/product/19.3.0/dbhome_1
export ORA_INVENTORY=/u01/app/oraInventory
export ORACLE_SID=cdb1
export PDB_NAME=pdb1
export DATA_DIR=/u02/oradata

export PATH=/usr/sbin:/usr/local/bin:\$PATH
export PATH=\$ORACLE_HOME/bin:\$PATH

export LD_LIBRARY_PATH=\$ORACLE_HOME/lib:/lib:/usr/lib
export CLASSPATH=\$ORACLE_HOME/jlib:\$ORACLE_HOME/rdbms/jlib
  1. Create a startup shell script.
cat > /home/oracle/scripts/start_all.sh <<EOF
. /home/oracle/scripts/setEnv.sh

. oraenv

dbstart \$ORACLE_HOME
  1. Create a stop shell script.
cat > /home/oracle/scripts/stop_all.sh <<EOF
. /home/oracle/scripts/setEnv.sh

. oraenv

dbshut \$ORACLE_HOME
  1. Update the owner and permission of the shell scripts and its parent directory.
chown -R oracle:oinstall /home/oracle
chmod u+x /home/oracle/scripts/*.sh
  1. Set the environment when the Bash runs whenever it is started interactively.
cat > /home/oracle/.bashrc <<EOF

# User specific aliases and functions

alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'

# Source global definitions
if [ -f /etc/bashrc ]; then
  . /etc/bashrc

. /home/oracle/scripts/setEnv.sh >> /home/oracle/.bashrc

chown oracle:oinstall /home/oracle/.bashrc

Create and Add New Swap File

  1. Run the following command, with oracle user, to create and apply new swap file.
dd if=/dev/zero of=/tmp/additional-swap bs=1048576 count=4096
chmod 600 /tmp/additional-swap
mkswap /tmp/additional-swap
  1. Apply the swap by executing the following command with root user.
swapon /tmp/additional-swap

Install Oracle Database

  1. Set the DISPLAY variable with oracle user.
  1. Unzip the archive with oracle user.
unzip -oq /path/to/software/LINUX.X64_193000_db_home.zip
  1. “Cheat” the installer about the distribution with oracle user.
  1. Run the installer, with oracle user, to install Oracle database.
./runInstaller -ignorePrereq -waitforcompletion -silent                        \
    -responseFile ${ORACLE_HOME}/install/response/db_install.rsp               \
    oracle.install.option=INSTALL_DB_SWONLY                                    \
    ORACLE_HOSTNAME=${ORACLE_HOSTNAME}                                         \
    UNIX_GROUP_NAME=oinstall                                                   \
    INVENTORY_LOCATION=${ORA_INVENTORY}                                        \
    SELECTED_LANGUAGES=en,en_GB                                                \
    ORACLE_HOME=${ORACLE_HOME}                                                 \
    ORACLE_BASE=${ORACLE_BASE}                                                 \
    oracle.install.db.InstallEdition=EE                                        \
    oracle.install.db.OSDBA_GROUP=dba                                          \
    oracle.install.db.OSBACKUPDBA_GROUP=dba                                    \
    oracle.install.db.OSDGDBA_GROUP=dba                                        \
    oracle.install.db.OSKMDBA_GROUP=dba                                        \
    oracle.install.db.OSRACDBA_GROUP=dba                                       \
    SECURITY_UPDATES_VIA_MYORACLESUPPORT=false                                 \
  1. If the setup is success, the following message should be printed on screen.
Successfully Setup Software.
  1. Execute the below scripts, with root user, to update the permission of Oracle directories and set the environment variables.

Database Creation

  1. Start the listener with oracle user.
lsnrctl start
  1. Create a database with oracle user.
dbca -silent -createDatabase                                                   \
     -templateName General_Purpose.dbc                                         \
     -gdbname ${ORACLE_SID} -sid  ${ORACLE_SID} -responseFile NO_VALUE         \
     -characterSet AL32UTF8                                                    \
     -sysPassword SysPassword1                                                 \
     -systemPassword SysPassword1                                              \
     -createAsContainerDatabase true                                           \
     -numberOfPDBs 1                                                           \
     -pdbName ${PDB_NAME}                                                      \
     -pdbAdminPassword PdbPassword1                                            \
     -databaseType MULTIPURPOSE                                                \
     -automaticMemoryManagement false                                          \
     -totalMemory 1000                                                         \
     -storageType FS                                                           \
     -datafileDestination "${DATA_DIR}"                                        \
     -redoLogFileSize 50                                                       \
     -emConfiguration NONE                                                     \

Listener Update

  1. Replace or edit the listener.ora file, with oracle user, to set the correct hostname, port number and SID name.
cat > /u01/app/oracle/product/19.3.0/dbhome_1/network/admin/listener.ora <<EOF
      (ADDRESS = (PROTOCOL = TCP)(PORT = 1539))

    (SID_DESC =
      (SID_NAME = ${ORACLE_SID})

  1. Reload the Oracle Listener.
lsnrctl reload

Post Installation

  1. Edit the /etc/oratab file, with root user, to update the restart flag from ‘N‘ to ‘Y‘.
  1. Configure the Database instance “orcl” with auto startup.
ln -s spfilecdb1.ora initorcl.ora
  1. Enable Oracle Managed Files (OMF) and make sure the PDB starts when the instance starts.
sqlplus / as sysdba <<EOF
alter system set db_create_file_dest='${DATA_DIR}';
alter pluggable database ${PDB_NAME} save state;
  1. Execute the following commands, with root user, to start the Oracle Listener automatically.
cat > /home/oracle/scripts/cron.sh <<EOF1

. /home/oracle/scripts/setEnv.sh

echo "\`date\`" > /home/oracle/scripts/last.log

lsnrctl start

sleep 3

lsnrctl reload

sleep 3

sqlplus /nolog <
conn / as sysdba


chown oracle:oinstall /home/oracle/scripts/cron.sh
chmod 744 /home/oracle/scripts/cron.sh
  1. Use the following command, with oracle user, to edit the crontab file.
crontab -e
  1. Put the following cron job in the first line of crontab file, then press the keys :wq to save and exit.
@reboot /home/oracle/scripts/cron.sh


  1. Login as oracle user and then execute the following commands one-by-one.
sqlplus /nolog
conn / as sysdba;
select * from v$version;
show pdbs;

Create New User and Tablespace

  1. Login as Sysdba with SqlPlus.
sqlplus / as sysdba
  1. Update the seesion setting _ORACLE_SCRIPT to true to allow common user comes without c## as prefix.
  1. Create a new tablespace with an automatic extensible size 100MB, maximum 10G in size.
-- Location of the dat file: /u01/app/oracle/product/19.3.0/dbhome_1/dbs/my_tablespace.dat
-- SELECT tablespace_name, block_size, max_size, status FROM DBA_TABLESPACES;
  DATAFILE 'my_tablespace.dat'
    SIZE 100M

  1. [Optional] Update the password life time from 180 days (default) to unlimited.
  1. Create a new user.
  1. Grant permissions to the new user.

ALTER USER newuser QUOTA UNLIMITED ON my_tablespace;
  1. [Optional] Grant DBA to the new user.
-- REVOKE DBA FROM newuser;
GRANT DBA TO newuser;


Windows 7 Activation

@echo off
title Activate Windows 7 / 8 / 8.1 / 10 for FREE!&cls&echo =====================================&echo #Copyright: MSGuides.com&echo =====================================&echo.&echo #Supported products:&echo – Windows 7 Professional&echo – Windows 7 Professional N&echo – Windows 7 Professional E&echo – Windows 7 Enterprise&echo – Windows 7 Enterprise N&echo – Windows 7 Enterprise E&echo – Windows 8 Core&echo – Windows 8 Core Single Language&echo – Windows 8 Professional&echo – Windows 8 Professional N&echo – Windows 8 Professional WMC&echo – Windows 8 Enterprise&echo – Windows 8 Enterprise N&echo – Windows 8.1 Core&echo – Windows 8.1 Core N&echo – Windows 8.1 Core Single Language&echo – Windows 8.1 Professional&echo – Windows 8.1 Professional N&echo – Windows 8.1 Professional WMC&echo – Windows 8.1 Enterprise&echo – Windows 8.1 Enterprise N&echo – Windows 10 Home&echo – Windows 10 Home N&echo – Windows 10 Home Single Language&echo – Windows 10 Home Country Specific&echo – Windows 10 Professional&echo – Windows 10 Professional N&echo – Windows 10 Education N&echo – Windows 10 Education N&echo – Windows 10 Enterprise&echo – Windows 10 Enterprise N&echo – Windows 10 Enterprise LTSB&echo – Windows 10 Enterprise LTSB N&echo.&echo.&echo ====================================&echo Activating your Windows… & cscript //nologo c:\windows\system32\slmgr.vbs /ipk FJ82H-XT6CR-J8D7P-XQJJ2-GPDD4 >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk MRPKT-YTG23-K7D7T-X2JMM-QY7MG >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk W82YF-2Q76Y-63HXB-FGJG9-GF7QX >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk 33PXH-7Y6KF-2VJC9-XBBR8-HVTHH >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk YDRBP-3D83W-TY26F-D46B2-XCKRJ >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk C29WB-22CC8-VJ326-GHFJW-H9DH4 >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk BN3D2-R7TKB-3YPBD-8DRP2-27GG4 >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk 2WN2H-YGCQR-KFX6K-CD6TF-84YXQ >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk NG4HW-VH26C-733KW-K6F98-J8CK4 >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk XCVCF-2NXM9-723PB-MHCB7-2RYQQ >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk GNBB8-YVD74-QJHX6-27H4K-8QHDG >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk 32JNW-9KQ84-P47T8-D8GGY-CWCK7 >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk JMNMF-RHW7P-DMY6X-RF3DR-X2BQT >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk M9Q9P-WNJJT-6PXPY-DWX8H-6XWKK >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk 7B9N3-D94CG-YTVHR-QBPX3-RJP64 >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk BB6NG-PQ82V-VRDPW-8XVD2-V8P66 >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk GCRJD-8NW9H-F2CDX-CCM8D-9D6T9 >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk HMCNV-VVBFX-7HMBH-CTY9B-B4FXY >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk 789NJ-TQK6T-6XTH8-J39CJ-J8D3P >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk TX9XD-98N7V-6WMQ6-BX7FG-H8Q99 >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk 3KHY7-WNT83-DGQKR-F7HPR-844BM >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk 7HNRX-D7KGG-3K4RQ-4WPJ4-YTDFH >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk PVMJN-6DFY6-9CCP6-7BKTT-D3WVR >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk W269N-WFGWX-YVC9B-4J6C9-T83GX >nul&cscript //nologo c:\windows\system32\slmgr.vbs /ipk MH37W-N47XK-V7XM9-C7227-GCQG9 >nul
echo ————————————&echo.&echo.&set i=1
if %i%==1 set KMS_Sev=kms7.MSGuides.com
if %i%==2 set KMS_Sev=kms8.MSGuides.com
if %i%==3 set KMS_Sev=kms9.MSGuides.com
if %i%==4 goto notsupported
cscript //nologo c:\windows\system32\slmgr.vbs /skms %KMS_Sev% >nul
cscript //nologo c:\windows\system32\slmgr.vbs /ato | find /i “successfully” && (echo.& echo ====================================== & echo. & choice /n /c YN /m “Would you like to visit my blog [Y,N]?” & if errorlevel 2 exit) || (echo The connection to the server failed! Trying to connect to another one… & echo Please wait… & echo. & echo. & set /a i+=1 & goto server)
explorer “http://MSGuides.com”&goto halt
echo ======================================&echo.&echo Sorry! Your version is not supported.
pause >nul

How to Install Webmin on CentOS 8

Webmin is a free, open-source and web-based system configuration and management tool for Unix-like operating systems. You can set up Apache web server, Samba, DNS, Mail, FTP, Database, File system and package management with Webmin web-based interface. Webmin is very similar to cPanel and provides an easy way to manage Linux systems through a web browser.


  • A server running CentOS 8.
  • A root password is configured on your server.

Getting Started

By default, SELinux is enabled in CentOS 8 server. So you will need to disable it first.

You can do this by editing /etc/selinux/config file:

nano /etc/selinux/config

Make the following changes:


Save and close the file. Then, restart your server to apply the changes.

Install Webmin with RPM

First, you will need to install the required dependencies by running the following command:

dnf install perl perl-Net-SSLeay openssl perl-Encode-Detect

Once all the dependencies are installed, download the Webmin RPM package from the Sourceforge download page with the following command:

wget https://prdownloads.sourceforge.net/webadmin/webmin-1.930-1.noarch.rpm

Once downloaded, run the following command to install Webmin:

rpm -ivh webmin-1.930-1.noarch.rpm

You should see the following output:

warning: webmin-1.930-1.noarch.rpm: Header V4 DSA/SHA1 Signature, key ID 11f63c51: NOKEY
Verifying...                          ################################# [100%]
Preparing...                          ################################# [100%]
Operating system is CentOS Linux
Updating / installing...
   1:webmin-1.930-1                   ################################# [100%]

Webmin install complete. You can now login to https://centos8:10000/
as root with your root password.

By default, Webmin runs on port 10000. You can check whether Webmin is running or not with the following command:

netstat -ant | grep 10000

You should see the following output:

tcp        0      0 *               LISTEN  

You can also check the Webmin process with the following command:

ps -ef | grep webmin

You should see the following output:

root      2131     1  0 12:29 ?        00:00:00 /usr/bin/perl /usr/libexec/webmin/miniserv.pl /etc/webmin/miniserv.conf
root      2225  6290  0 12:30 pts/0    00:00:00 grep --color=auto webmin

Install Webmin with Yum Repository

You can also install the Webmin from CentOS Yum repository. First, create a Webmin repository with the following command:

nano /etc/yum.repos.d/webmin.repo

Add the following lines:

name=Webmin Distribution Neutral

Save and close the file. Then, download and add the repository signing key with the following command:

wget http://www.webmin.com/jcameron-key.asc
 rpm --import jcameron-key.asc

Next, install the Webmin by running the following command:

dnf install webmin

Once the installation is completed, you should see the following output:

Installing       : webmin-1.930-1.noarch                                                       2/2 
Running scriptlet: webmin-1.930-1.noarch                                                       2/2 
Webmin install complete. You can now login to https://centos8:10000/
as root with your root password.

Access Webmin in Browser

By default, Webmin listens on port 10000. So you will need to open the Webmin port in firewalld. You can do it with the following command:

firewall-cmd --zone=public --add-port=10000/tcp --permanent
 firewall-cmd --reload

Now, open your web browser and type the URL https://your-server-ip:10000. You will be redirected to the following page:

Provide your root user, password and click on the Sign in button. You should see the Webmin dashboard in the following page:

From here, you can configure and manage your CentOS 8 server easily.Advertisements


Congratulations! you have successfully installed Webmin on CentOS 8 server. You can now easily install LAMP/LEMP server, FTP server and hosting your website easily through the Webmin web interface.

How to Activate Windows 10 Pro with CMD

Step 1. Click Start and type cmd, right-click Command Prompt app and choose Run as administrator.

Step 2. Copy and paste the following command line in Command Prompt window and hit Enter. If you find other keys for Windows 10 Pro, you can replace it with the key in the command line after slmgr /ipk.

slmgr /ipk W269N-WFGWX-YVC9B-4J6C9-T83GX

Step 3. Type the following command lines and remember to hit Enter after you type each line.

slmgr /skms kms.xspace.in

slmgr /ato

How to Check If Your Windows 10 Is Activated or Not

If you want to check whether your Windows 10 computer is activated or not, you can press Windows + R keys on the keyboard to open Run box, type slmgr.vbs -xpr in Run box and hit Enter.

Free Web Hosting