/usr/bin/swipl-ld is in swi-prolog-nox 6.6.4-2ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/bin/../lib/swi-prolog/bin/amd64/swipl-ld
/usr/bin/../lib/swi-prolog/bin/amd64/swipl-ld