[GENERAL] psql remote shell command

[Dennis]

Is it possible to execute command in on system the is hosting postgresql 
remotely using psql or other mechanism?  I know I can use \! in psql but that 
executes the commands on the host where I am running psql from.  Also, is it 
possible for a postgres login/user to stop or restart a running postgres 
instance from in side psql or similar client. e.g. psql -c “pg_ctl stop -D 
some_data_dir”