Install Speedtest-cli On a CentOS / RHEL / Scientific / Fedora Linux To Check Internet Speed

Originally published at: https://www.cyberciti.biz/faq/install-speedtest-cli-on-centos-redhat-fedoa-scientific-to-measure-internetspeed/

I do not want to use Adobe flash based speed testing site due to security concern on my desktop. How do I install Speedtest-cli on a CentOS Linux or Fedora Linux or Red Hat Enterise Linux (RHEL) for checking the Internet speed?