pg_standby exit codes

Hey all,

For a variety of reasons, that aren't relevant here, I have had to implement
my own version of pg_standby.
At the moment it puts the WAL in the right place and "exit 0". Postgres then
processes it, and calls pg_standby again, as it should. It'll do this
basically forever.
It has a test for a "trigger" file which causes it to exit 1, making postgres
stop recovering and start.
I would very much like to be able to make pg_standby cause postgres to cleanly
shutdown, with or without removing recovery.conf. Is there a magic exit code
I can use to do this? Or a pg_ctl option to stop recovering and shutdown?

Thanks

--
Mike Williams