Description
   pg_controldata returns information initialized during
   initdb, such as the catalog version and server locale.
   It also shows information about write-ahead logging and checkpoint 
   processing.  This information is server-wide, and not specific to any one
   database.
  
   This utility may only be run by the user who installed the server because
   it requires read access to the datadir.
   You can specify the data directory on the command line, or use 
   the environment variable PGDATA.