Magenta is actually correct. $post_ID is a WP_Post object. Your exec code should effectively be using $post_ID->ID.
function save_new_post($post_ID)
{
print_r($post_ID);
die();
Returns
WP_Post Object ( [ID] => ...
Magenta is actually correct. $post_ID is a WP_Post object. Your exec code should effectively be using $post_ID->ID.
function save_new_post($post_ID)
{
print_r($post_ID);
die();
Returns
WP_Post Object ( [ID] => ...