How to Check and Monitor CPU utilization on Linux

How to Check and Monitor CPU utilization on Linux

As a Linux administrator, it’s important to keep an eye on how your server (or servers) is performing. One way to measure its performance is to track the CPU usage. This will give you insight into the performance of the system as well as show how the hardware resources are being divided up across the various running services.

In this guide, we’ll go over a few methods to check and monitor the CPU utilization on a Linux system. Whether you are in charge of a server or just your personal desktop, the computer’s CPU usage is useful information that’s easy to acquire.

In this tutorial you will learn:

  • How to check CPU usage with top
  • Understanding the output from top and htop
  • Monitor CPU usage with systat package
  • How to configure CPU monitoring alters

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GCC the C compiler on RHEL 8 and Hello world C program example.

How to install GCC the C compiler on RHEL 8 / CentOS 8

The objective of this guide is to install GCC the C compiler on RHEL 8 / CentOS 8 and perform compilation of a basic C “Hello World” program. The GCC compiler can be installed in RHEL 8 by simply using the dnf install command.

In this tutorial you will learn:

  • How to install GCC compiler on RHEL 8 / CentOS 8.
  • How to install Development Tools installation group.
  • How to write C program.
  • How to compile and execute C program.

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Installed PuTTY on Red Hat Enterprise Linux 8.

How to install putty in RHEL 8 / CentOS 8

Putty is GUI SSH, Telnet and Rlogin alternative client for graphical user interface. PuTTY is not a part of the standard RHEL 8 / CentOS 8 repository however can be installed from the EPEL repository directly as an RPM package using the dnf command.

In this tutorial you will learn:

  • How to install PuTTY on RHEL 8 / CentOS 8 using the dnf command.
  • How to launch PuTTY.

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File conversion with alien doesn't take long

How to install deb file in RHEL 8 / CentOS 8 Linux

There may come a time when that package you want to install in RHEL 8 / CentOS 8 is simply not available as a RPM file. The alternative is to download the source and compile it yourself, or – alternatively – generate a RPM file from that source code later on.

But there is another way. Given the fact that Debian-based distributions have way more users than RPM-based ones, the number of available packages in their repositories is greater. Chances are you will be able to find a DEB file for that package you want. Here is how to install that DEB file in RedHat Linux with the help of a small utility called alien.

In this tutorial you will learn:

  • How to install alien in RHEL 8 / CentOS 8
  • How to convert a DEB package to a RPM one

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Nmap command on RHEL 8 Linux Server/Workstation

Install nmap on RHEL 8 / CentOS 8

The nmap command is an invaluable tool for any system or network administrator. This command is not available on RHEL 8 / CentOS 8 default installation. However, it can be installed with a single dnf command.

In this tutorial you will learn:

  • How to install Nmap command on RHEL 8 / CentOS 8.
  • How to to check Nmap version on RHEL 8 / CentOS 8.

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Checking version of installed AWS CLI tools on RHEL 8

Install aws cli on RHEL 8 / CentOS 8

The AWS Command Line Interface (CLI) is a all-in-one tool to manage services available on AWS cloud. On RHEL 8 / CentOS 8 the AWS CLI can be installed by using the python package management system PIP.

In this tutorial you will learn:

  • How to install AWS CLI tools on RHEL 8 / CentOS 8
  • How to configure AWS CLI tools on RHEL 8 / CentOS 8
  • How to remove AWS CLI tools on RHEL 8 / CentOS 8

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Check open ports on RHEL 8 Linux firewall using firewall-cmd command.

How to check open ports on RHEL 8 / CentOS 8 Linux

Firewalld is a an underlining mechanism for firewall configuration on RHEL 8 / CentOS 8. Current RHEL 8 / CentOS 8 version of the Firewalld daemon is based on Nftables. To check open ports on RHEL 8 / CentOS 8 you can use the firewall-cmd command as shown below. We will also discuss how to check open ports remotely with the nmap command.

In this tutorial you will learn:

  • How to check open ports on RHEL 8.
  • How to check services on RHEL 8.
  • How to check open ports remotely using nmap.
  • How to list open ports and service with firewall-cmd.

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YUM on RHEL 8

How to Install YUM on RHEL 8 / CentOS 8

Fedora made the change to DNF back with Fedora 22, but CentOS and RHEL have stayed with YUM, until now. RHEL has jumped to the next gen package manager, and that’s a good thing, but if you’re missing YUM or have scripts that rely on it, you’ll still have access to the old package manager. What’s even better, you don’t need to do anything extra.

In this tutorial you will learn:

  • How to Use YUM on RHEL 8 / CentOS 8
  • What is YUM on RHEL 8 / CentOS 8, Really
  • Is there a Difference?

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Use the repoquery command to list all available packages in RHEL 8 / CentOS 8

How to list installed packages on RHEL 8 / CentOS 8 Linux

There might come a time when you want to know if you have already installed a certain package on your RHEL 8 / CentOS 8. An application to be manually installed might require certain dependencies to work so you’ll have to check beforehand if these are satisfied. Or you might want to compile something and want to make sure you have all the right header libraries on your system.

In this tutorial you will learn:

  • How to use yum and dnf in RHEL 8 / CentOS 8 to list all packages
  • How to use the repoquery command to accomplish the same task
  • How to use the rpm command to list all packages installed on RHEL 8 / CentOS 8
  • How to filter the output of each command to seek certain packages
Use the repoquery command to list all available packages in RHEL 8 / CentOS 8

Use the repoquery command to list all available packages in RHEL 8 / CentOS 8

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How to create a simple encrypted Two-Way SSH tunnel

How to create a simple encrypted Two-Way SSH tunnel

Why would you need to create a simple Two-Way SSH tunnel? In your Linux system administration job have you ever found your self in a situation in which you cannot SSH to a any of your servers/hosts that may be behind a firewall, NAT or otherwise obstructed from an easy access.

In order to gain the access, you would need to reconfigure the firewall or create VPN which could be an enormous overhead just because you need to execute few commands from now and then. With Two-Way SSH tunnel you can connect to any destination under a single condition, which is, the ability to ssh login from the destination to the source.

If you can do that, you can as well reverse login from source to destination even if it is behind firewall or NAT.

In this tutorial you will learn:

  • How to create Two-Way SSH tunnel

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