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How To enable the EPEL Repository on RHEL 8 / CentOS 8 Linux

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Although it’s been a while since the release of Red Hat Enterprise Linux 8, the corresponding version of the EPEL repository (Extra Packages for Enterprise Linux) was only released few days ago. The repository contains packages that are not provided by the official software sources, as for example extundelete, an utility to recover deleted files from ext3/4 filesystems. Until now the solution to install those software was to build it from source or to use the previous version of EPEL (less than ideal). In this tutorial we will see how to add EPEL8 to RHEL 8 / CentOS 8.

In this tutorial you will learn:

  • How to add the EPEL8 repository to RHEL 8 / CentOS 8
  • How to check all the packages contained in the EPEL8 repository


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How to install Docker CE on RHEL 8 / CentOS 8

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The latest release of the RHEL 8 / CentOS 8. Red Hat has built its own tools, buildah and podman, which aim to be compatible with existing docker images and work without relying on a daemon, allowing the creation of containers as normal users, without the need of special permissions (with some limitations: e.g. at the moment of writing, it’s still not possible to map host ports to the container without privileges).

Some specific tools, however, are still missing: an equivalent of docker-compose, for example does not exists yet. In this tutorial we will see how to install and run the original Docker CE on Rhel8 by using the official Docker repository for CentOS7.

In this tutorial you will learn:

  • How to enable the docker-ce repository on RHEL 8 / CentOS 8
  • How to install docker and docker-compose on RHEL 8 / CentOS 8

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Docker installed on RHEL 8 / CentOS 8

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How to add a user to a group on RHEL 8 / CentOS 8

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In the context of a discretionary access control (DAC) mechanism, the access to system resources, files and directories, is based on the identity of the users and on the groups they are member of. This type of access control is called “discretionary” because a user can perform its own policy decisions (limited by its own permissions, of course). In this tutorial we will see how to add a user to a group and what is the difference between a primary and a secondary group on a RHEL 8 / CentOS 8 Linux system.

In this tutorial you will learn:

  • What is the difference between a primary and a secondary group
  • How to add a user to a group by using the usermod command
  • How to add a user to a group directly with vigr

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How to add a user to a group on Rhel8

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How to install ntfs-3g on RHEL 8 / CentOS 8

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NTFS is not supported by default on RHEL 8 / CentOS 8. To make our system able to read and write block devices formatted with this proprietary filesystem, we need to install the ntfs-3g software, which usually in provided by third party repositories like Epel. At the time of writing, however, a version of this software source for Rhel8 doesn’t already exist, therefore we will see how to install it from source in few easy steps.

In this tutorial you will learn:

  • How to build ntfs-3g from source
  • How to install ntfs-3g
  • How to mount a block device formatted with ntfs-3g
  • How to format a block device with the ntfs filesystem
  • How to check the ntfs filesystem integrity using ntfsfix

ntfs-3g-manpage

The manpage of ntfs-3g on Rhel 8

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Testing Internet connection speed from a Linux command line using speedtest-cli command

How to run a speed test from command line using speedtest-cli

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Running a speed test can be very useful to verify the current state of an internet connection, for example, to verify that our ISP (Internet Service Provider) is respecting the parameters we are paying for, or to diagnose possible problems.

One of the most common ways to check ping, download and upload values is to run a test from the speedtest.net website. The speedtest-cli program let us run the same test from our beloved command line interface.

In this tutorial you will learn:

  • How to install and use the speedtest-cli application
  • What are the most useful options we can use to modify its behavior
Testing Internet connection speed from a Linux command line using speedtest-cli command

Testing Internet connection speed from a Linux command line using speedtest-cli command

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Introduction to Ebay API with python: The Merchandising API - Part 4

Introduction to Ebay API with Python: The Merchandising API – Part 4

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The Ebay Merchandising API is the focus of this fourth and last article of the series dedicated to python and Ebay APIs.

This API provides less calls than the ones we previously saw, but among them, one that can be very useful: getMostWatchedItems: we will focus on it.

In this tutorial you will learn:

  • What are the calls provided by the Merchandising API
  • How to use the getMostWatchedItems call

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Introduction to Ebay API with python: The Trading API - Part 3

Introduction to Ebay API with Python: The Trading API – Part 3

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This is the third article of the series dedicated to Ebay APIs and their use via python. In the first article we saw how to setup our working environment, creating a developer and a sandbox “test” account, generating our API keys and installing the python SDK.

In the second article we approached the Finding API, focusing on the findItemsByKeywords call. In this article we will introduce the Trading API.

In this tutorial you will learn:

  • What are some of the most useful “Trading API” calls
  • How to create an item by using the AddItem API call

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Introduction to Ebay API with python: The Finding API - Part 2

Introduction to Ebay API with Python: The Finding API – Part 2

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In the previous article we saw how to perform the preliminary steps to prepare our working environment, create an Ebay developer and a sandbox account and generate the keys and credentials needed to execute API calls. In this new chapter we will create our first request and perform our first call focusing on the “Finding API”

In this tutorial you will learn:

  • What are the possible “Finding API” calls;
  • What are the parameters you can use to customize you call;
  • How to build a request with the python SDK;
  • How to perform an API call;

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Introduction to Ebay API with python: Obtaining keys and accessing the sandbox - Part 1

Introduction to Ebay API with Python: Obtaining keys and accessing the sandbox – Part 1

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Ebay is one of the biggest ecommerce sites. Many people use it to search and buy products, and many stores use it to enlarge their audience and expand their business range.

If we want to operate programmatically on Ebay, for example to mass create or modify a set of items, or quickly confront prices, we must use the dedicated application programming interfaces. In this tutorial we will see how to prepare our working environment in order to use python to interact with the Ebay APIs.

In this tutorial you will learn:

  • How to create an Ebay developer account and generate APIs keys
  • What is the Ebay sandbox and how create a sandbox user.
  • How to obtain the Ebay python SDK.

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Introduction to higher order functions in Javascript

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By definition, an higher order function is a function which, at least, receives one or more other functions as arguments or returns another function as its result. In this tutorial we will focus on standard library functions as filter, map and reduce: we will see when they can be useful and how to use them.

In this tutorial you will learn:

  • What is an higher order function.
  • Why we can use higher order functions in Javascript.
  • How and when to use filter, map and reduce functions.

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How to use arrow functions in Javascript

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The arrow functions syntax was introduced with ECMAScript6: by using this new syntax, in some (but not all) cases, we can produce more concise and readable code, especially when our function contains only one expression. In this tutorial we will see how we can define an arrow function, what are the differences with standard functions and what are the cases in which the use of arrow functions is not appropriate.

In this tutorial you will learn:

  • What is an arrow function.
  • How an arrow function is defined.
  • The differences between arrow functions and standard functions.
  • The cases in which arrow functions cannot be used.

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