pg_ctl with unix domain socket?

Hello,

I have created a fresh cluster with

   initdb -D /some/path/pgtest

I can start postgres to run on unix domain socket serving this cluster with:

   postgres -D /some/path/pgtest -h '' -k /some/path/pgtest

But I'd like to use pg_ctl instead, in order to have clean control:

   PGPORT=/some/path/pgtest pg_ctl -D/some/path/pgtest -l postgreslog start


Any hints how to use pg_ctl to start/stop postgresql on a unix domain socket?