Pecl Ubuntu 19.04 Installation Guide
How to Install PHP 7 PECL on Ubuntu 19.04 Disco GNU/Linux.
And PECL for Ubuntu 19.04 (PHP Extension Community Library) is a Repository of Extensions for the PHP programming language.

Contents
$schemamarkup = get_post_meta(get_the_ID(), 'schemamarkup', true); if(!empty($schemamarkup)) { echo $schemamarkup; }
How to Install PHP 7 PECL on Ubuntu 19.04 Disco GNU/Linux.
And PECL for Ubuntu 19.04 (PHP Extension Community Library) is a Repository of Extensions for the PHP programming language.