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This article covers how to install Go on CentOS 8. Go language was designed to resolve the common criticisms of other languages while maintaining their positive characteristics and most widely used for writing servers these days.


Run the below command to see the version of the Go language:

$ go version



This article covers how to install and manage multiple Java versions on CentOS 7 system. At the end you also learned how to set default Java version. Java is used for developing anything from lightweight mobile to desktop applications.


How to Install Java 8 on CentOS ?

1. Update the system before installing any new programs:

$ yum -y update

2. Install Java 8:

$ yum install java-1.8.0-openjdk

3. Verify Java is Installed

$ java -version



This article covers how to perform Docker installation and Configuration. Also, you will learn how to install Docker CE on the CentOS 8 system. Docker container technology allows you to run applications in a specific and isolated environment.

Docker Community Edition (CE) is the new name for the free Docker product.

To Install Docker CE on Linux:
1. Remove all existing docker applications (that might currently be installed) in order to make sure we are using a clean installation.:

# yum remove docker docker-client docker-client-latest docker-common docker-latest docker-latest-logrotate docker-logrotate docker-engine

2. Add an external repository that will help us obtain the Docker software:

# dnf config-manager --add-repo=https://download.docker.com/linux/centos/docker-ce.repo

3. Check what versions of docker we have in the repository:

# dnf list docker-ce

4. Install the version that best matches our CentOS server version:

# dnf install docker-ce --nobest

5. We can double-check if the installation was successful by using the version command:

# docker -v



This article covers how to reset or change your MySQL root password on Red Hat Enterprise Linux 8.

MySQL is an open source relational database management system (RDBMS) with a client-server model for creating and managing databases based on a relational model.


To Reset the MySQL root password:

You must run the commands in the following steps as the root user. 

Therefore, you can either log in directly as the root user (which is not recommended for security reasons), or use the su or sudo commands to run the commands as the root user.

To reset the root password for MySQL, follow these steps:

1. Log in to your account using SSH.

2. Stop the MySQL server using the appropriate command for your Linux distribution:

For CentOS and Fedora, type:

$ service mysqld stop

For Debian and Ubuntu, type:

$ service mysql stop

3. Restart the MySQL server with the —skip-grant-tables option. To do this, type the following command:

$ mysqld_safe --skip-grant-tables &

4. Log into MySQL using the following command:

$ mysql

5. At the mysql> prompt, reset the password. To do this, type the following command, replacing new-password with the new root password:

UPDATE mysql.user SET Password=PASSWORD('new-password') WHERE User='root';

6. At the mysql> prompt, type the following commands:

FLUSH PRIVILEGES;
exit;

7. Stop the MySQL server using the following command.

You will be prompted to enter the new MySQL root password before the MySQL server shuts down:

$ mysqladmin -u root -p shutdown

8. Start the MySQL server normally. To do this, type the appropriate command for your Linux distribution:

For CentOS and Fedora, type:

$ service mysqld start

For Debian and Ubuntu, type:

$ service mysql start



This article covers how to secure Red Hat Enterprise Linux 8 with UFW. UFW may not be intended to provide complete firewall functionality, but it does provide an easy way to create and manage simple firewall rules.

A firewall is a way to protect machines from any unwanted traffic from outside. 

It enables users to control incoming network traffic on host machines by defining a set of firewall rules. 

These rules are used to sort the incoming traffic and either block it or allow through.

Note that firewalld with nftables backend does not support passing custom nftables rules to firewalld, using the --direct option.


How to start, stop, restart firewalld service on an RHEL 8?

By now you know about firewalld zones, services, and how to view the defaults. It is time to activate and configure our firewall.

1. Start and enable firewalld

$ sudo systemctl start firewalld
$ sudo systemctl enable firewalld

2. Stop and disable firewalld

$ sudo systemctl stop firewalld
$ sudo systemctl disable firewalld

3. Check the firewalld status

$ sudo firewall-cmd --state

4. Command to reload a firewalld configuration when you make change to rules

$ sudo firewall-cmd --reload

5. Get the status of the firewalld service

$ sudo systemctl status firewalld


When to use firewalld, nftables, or iptables:

1. firewalld: Use the firewalld utility for simple firewall use cases. The utility is easy to use and covers the typical use cases for these scenarios.

2. nftables: Use the nftables utility to set up complex and performance critical firewalls, such as for a whole network.

3. iptables: The iptables utility on Red Hat Enterprise Linux 8 uses the nf_tables kernel API instead of the legacy back end. 

The nf_tables API provides backward compatibility so that scripts that use iptables commands still work on Red Hat Enterprise Linux 8. For new firewall scripts, Red Hat recommends to use nftables.



This article covers how to take Backups and restore a MySQL database on Red Hat Enterprise Linux 8.


Advantage of logical backup:

The main advantage of logical backup over physical backup is portability and flexibility. 

The data can be restored on other hardware configurations, MariaDB versions or Database Management System (DBMS), which is not possible with physical backups.

Note that physical backup must be performed when the mariadb.service is not running or all tables in the database are locked to prevent changes during the backup.


The mysqldump client is a backup utility, which can can be used to dump a database or a collection of databases for the purpose of a backup or transfer to another database server. 

The output of mysqldump typically consists of SQL statements to re-create the server table structure, populate it with data, or both. 

Alternatively, mysqldump can also generate files in other formats, including CSV or other delimited text formats, and XML.


Advantages of Physical backup:

1. Output is more compact.

2. Backup is smaller in size.

3. Backup and restore are faster.

4. Backup includes log and configuration files.


You can use one of the following MariaDB backup approaches to back up data from a MariaDB database:

1. Logical backup with mysqldump

2. Physical online backup using the Mariabackup tool

3. File system backup

4. Replication as a backup solution


To Backing up an entire database with mysqldump:

Execute the command:

# mysqldump [options] db_name > backup-file.sql


Using mysqldump to back up a set of tables from one database:

To back up a subset of tables from one database, add a list of the chosen tables at the end of the mysqldump command:

# mysqldump [options] db_name [tbl_name …​]



To restore the data while keeping the original backup files, use the following procedure:

1. Run the mariabackup command with the --copy-back option:

$ mariabackup --copy-back --target-dir=/var/mariadb/backup/

2. Fix the file permissions.

When restoring a database, Mariabackup preserves the file and directory privileges of the backup. However, Mariabackup writes the files to disk as the user and group restoring the database. 

For example, to recursively change ownership of the files to the mysql user and group:

# chown -R mysql:mysql /var/lib/mysql/

3. Start the mariadb service:

# systemctl start mariadb.service



This article will guide you on steps to perform Perl installation on #CentOS 8. You will also learn how to create and execute the #Perl #script on your CentOS system by using the terminal #commands.

Perl is a programming language that can be used to perform tasks that would be difficult or cumbersome on the command line.

To run a Perl script in Linux:

1. Run the "perl" command with the Perl script included in the command line.

2. Run the "perl" command with the Perl script supplied from the standard input stream.

3. Run the "perl" command with the Perl script supplied in a file.

4. Run Perl script files as commands.




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