Obtenha toda a meta post
//Get the meta for all keys:
<?php $meta = get_post_meta($post_id); ?>
Andrew Lautenbach
//Get the meta for all keys:
<?php $meta = get_post_meta($post_id); ?><?php $key_1_value = get_post_meta( get_the_ID(), 'key_1', true ); ?>
<?php if ( get_post_meta( get_the_ID(), 'thumb', true ) ) : ?>
<a href="<?php the_permalink() ?>" rel="bookmark">
<img class="thumb" src="<?php echo esc_url( get_post_meta( get_the_ID(), 'thumb', true ) ); ?>" alt="<?php the_title_attribute(); ?>" />
</a>
<?php endif; ?>