read -rd $'\000' newlink <<EOF; arv link create --link "$newlink"
{
-"tail_kind":"arvados#user",
"tail_uuid":"$user_uuid",
-"head_kind":"arvados#virtualMachine",
"head_uuid":"$vm_uuid",
"link_class":"permission",
"name":"can_login",
read -rd $'\000' newlink <<EOF; arv link create --link "$newlink"
{
-"tail_kind":"arvados#user",
"tail_uuid":"$user_uuid",
-"head_kind":"arvados#repository",
"head_uuid":"$repo_uuid",
"link_class":"permission",
"name":"can_write",