Question: drop database problem

Dear list,

I'm using Postgresql 7.2 on Solaris.

I have this error message when I try to drop a database. I couldn't find a
mention anywhere on this error. Could someone advise how to circumvent
this error?

pgsql=# drop database mydb;
ERROR: Postmaster environment variable 'PGDATA3' not set

The database owner is pgsql, and if I echo $PGDATA3 as the owner, it
returns a valid directory. Also, the datpath is correct.

select * from pg_database; shows
datname ... datpath
-----------------+...+---------
mydb PGDATA3

In the $PGDATA3/data/base/ directory, I confirmed that one of the
directories is being used, by bulk inserting some test data into mydb
database.

Also, I have several databases sharing the datpath of PGDATA3. Is there a
system table associating the datpath and the actual OS path? (like mydb ->
$PGDATA3/data/base/335253, etc.)

dropdb gives the same result.
ERROR: Postmaster environment variable 'PGDATA3' not set
dropdb: database removal failed

Thanks in advance.

Ben Kim
Database Developer/Systems Administrator
College of Education
Texas A&M University