pg_controldata
Name
pg_controldata -- display control information of a 
PostgreSQL database cluster
Synopsis
pg_controldata [datadir]
Description
   pg_controldata prints 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 cluster-wide, and not specific to any one
   database.
  
   This utility may only be run by the user who initialized the cluster because
   it requires read access to the data directory.
   You can specify the data directory on the command line, or use 
   the environment variable PGDATA.
  
Environment
- PGDATA
-       Default data directory location