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

How to Get Started With Xinput on Gnu/Linux Distros

GNU/Linux Xinput QuickStart Guide

Hi! The linked Tutorials Show you Step-by-step How to Install and Getting Started with xinput Command Line Tool in GNU/Linux Desktops.

And xinput for GNU+Linux is a Utility to configure and test X input Devices, such as Mouses, Keyboards, and Touchpads

Most noteworthy this Guide make use also of the evdev and some others CLI Utilities.

How to Getting Started with Xinput on GNU/Linux Distros

GNU/Linux Xinput QuickStart Guide