How to Fix yum Could not resolve host: repo Unknown error

You may receive a problem with yum not being able to resolve hosts when you try to install a yum package. I’m using CentOS 7. yum install wget

If you already have Internet connection and can ping 8.8.8.8, the likely problem is that you don’t have nameservers in your /etc/resolv.conf. vi /etc/resolv.conf If /etc/resolv.conf does not have any nameservers, you can add this line somewhere in the file: nameserver 8.8.8.8 Note: if you have used dhclient command, you should...

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How to Change hostname on CentOS 7

The best way to change hostname on CentOS 7 is editing the actual file that controls the hostname. vi /etc/hostname Originally, it is: localhost.localdomain But, we’ll delete that line and change it to: buhpc2 buhpc is our hostname, but it also has the subdomain, 2.buhpc.com, that I have configured. Now, the second file that we also have to change is /etc/hosts. vi /etc/hosts The original file looks like:

You create a new line with IP address hostname subdomain. If...

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How to Create SSH Keys for Secure SSH Access

Create SSH keys for SSHing SSH keys allow you to SSH into a machine without a password prompt. Before we create our SSH key, make sure that we have a ~/.ssh folder. If not, create the ~/.ssh folder. mkdir ~/.ssh Now, we can use the following command to generate an SSH public key and private key: ssh-keygen -t rsa -b 4096 -C “[email protected]” -t represents the encryption scheme. -b represents the number of bits. -C is used for e-mail identification. You...

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How to Setup Shortcuts for SSH

Instead of using SSH on an IP address that you’ll definitely forget, you can use shortcuts instead! For instance, instead of typing: ssh [email protected] Wouldn’t you rather do something like:

  Creating SSH shortcuts To create shortcuts, you have to create a file inside your home directory’s .ssh folder called config.

If the ~/.ssh directory does not exist.

Now, we can create the config file.

For every IP address that you want to add a shortcut, add...

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How to Set Static IP Address on CentOS 7

This blog post will show you how to set a static IP address on CentOS 7 from scratch with no prior knowledge of any information about the network. See if NetworkManager is running. NetworkManager is a network daemon that handles our network interfaces dynamically, but we’ll change our network scripts to set static configurations. We should stop this service. systemctl status NetworkManager systemctl stop NetworkManager Check what interfaces are available. nmcli d

Connect your Ethernet cable into the computer.  ...

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How to Install CentOS 7 Minimal Without a Mouse on Troubleshooting Basic Graphics Mode

Here are the list of steps to install CentOS 7 minimal without a mouse on a node or computer with no apparent graphics card. Why do we have to use troubleshooting mode? Without the graphics card, the node or machine tends to freeze at setup because there is no graphics card to render the setup properly, so we have to use troubleshooting mode and take advantage of installing CentOS 7 in basic graphics mode.   Steps First, follow Create Bootable USB...

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How to Install CUDA on NVIDIA Jetson TX1 [Deprecated]

Updated 2016 post – detailed version. (The method shown in this guide is outdated) This guide shows you how to install CUDA on the NVIDIA Jetson TX1. Currently, Nvidia’s Jetpack installer does not work properly. This blog post will show a work-around for getting CUDA to work on the TX1. Download the following files inside a directory first. Here are the two links for the files that you will need to download beforehand: Jetpack installer Deb file for upgrading sources...

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How to Create Bootable USB Flash Drive of CentOS 7 Minimal ISO

This article will provide the step to step instructions to create a bootable USB flash drive of CentOS 7 Minimal ISO on Windows, Mac, or Linux. The CentOS instance that we will install onto the bootable USB flash drive is CentOS-7-x86_64-Minimal-1503-01.iso.   Requirements Windows: You will need to use a program like Cygwin. I have another blog post, teaching how to install Cygwin on Windows machines. Macs and Linux: Your terminal will have the command already as a part of the...

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How to Setup MPI on CentOS 7 – 2 Connected Virtual Machines Part 2

For this blog post, I will be building on top of the Virtual Machine Clustering and NFS Server Setup in part 1. As a result, before you follow the steps of this post, you will want to have a similar setup like I have instructed in part 1: http://www.slothparadise.com/how-to-connect-virtual-machines-and-setup-nfs-server-part-1/ MPI stands for Message Passing Interface. MPI isn’t your average networking library. It’s optimized for performance, takes the fastest transport for running parallel programs across machines, and is a usable protocol library...

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How to Connect 2 Virtual Machines and Setup NFS Server Part 1

Here are a series of tutorials for beginners to get started in clustering virtual machines and learn how to parallel program. We will be using VirtualBox and CentOS in this article to simulate a clustered supercomputer. VirtualBox CentOS I have an article on how to install VirtualBox, which is a program that allows you to create and use virtual machines. CentOS is a popular Linux operating. I’m writing these articles to teach the basics on what makes a supercomputer and...

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