how to exec a process in a jail while being on the main host?

[Artem Kuchin]

For example, i have an already runing jail with some JID and i am logged 
in on the main host (which runs the jail).
How can i run a new process inside the jail with a known JID w/o ssh-ing 
into that jail or doing a lot of strange
manupulations?

I am asking, because i have about 20 jails running and each has a 
running special control daemon which
changes a lot and often. When change occures i need then to enter each 
jail as root, kill the old daemon, start the new one.
This take a lot of time and is really annoying.

--
Regards,
Artem