$schemamarkup = get_post_meta(get_the_ID(), 'schemamarkup', true); if(!empty($schemamarkup)) { echo $schemamarkup; }

How to Install CURL on RHEL-based Distros

GNU/Linux RHEL-based Installing cURL Guide

How to Install cURL on RHEL-based GNU/Linux Distributions – Step by step Tutorial.

And cURL for CentOS is a Computer Software Project providing a Library libcurl and Command-Line Tool curl for Transferring Data using various Network Protocols.

Step-by-step cURL CentOS Installation Guide - Featured

GNU/Linux RHEL-based Curl Installation Guide