Postgres regression fails completely

Hi,

I just installed PostgressSQL 6.5.1 on a Linux P100 box (RH 5.2, Linux
2.0.36). I completed the installation and preliminary tests up to step
20 in the installation section of the Admin. guide. I then started
postmaster as postgres superuser using (step 21):

nohup postmaster > regress.log 2>&1 &

When I attempt to run the regression tests by following the steps in 22
(a) of the guide, I get the following output.

See regress/README for more information.

=============== destroying old regression database... =================
Connection to database 'template1' failed.
connectDB() -- connect() failed: No such file or directory
Is the postmaster running at 'localhost' and accepting connections on
Unix socket '5432'?

destroydb: database destroy failed on regression.
=============== creating new regression database...   =================
Connection to database 'template1' failed.
connectDB() -- connect() failed: No such file or directory
Is the postmaster running at 'localhost' and accepting connections on
Unix socket '5432'?

createdb: database creation failed on regression.
createdb failed
ACTUAL RESULTS OF REGRESSION TEST ARE NOW IN FILE regress.out

To run the optional big test(s) too, type 'make bigtest'
These big tests can take over an hour to complete
These actually are: numeric_big
rm regress.o

I am relatively new to unix/Linux & I don't know how to check which
socket is being used. Or possibly the makefile needs to be edited to
provide a correct path?

Can you help?

Many thanks,

Roger Mason