[ -n "$order" ] && page_link="${page_link}o=${order}&"
[ -n "$search" ] && page_link="${page_link}s=${search}&"
[ -n "$filter" ] && page_link="${page_link}f=${filter}&"
[ -n "$order" ] && page_link="${page_link}o=${order}&"
[ -n "$search" ] && page_link="${page_link}s=${search}&"
[ -n "$filter" ] && page_link="${page_link}f=${filter}&"