psql v. postmaster

PostgreSQL 7.0.3
SunOS amber 5.8 Generic_108529-05 i86pc i386 i86pc
gcc version 2.95.2 19991024 (release)

configure
	--with-perl
	--enable-syslog
	--with-locale
	--with-odbc
postmaster -S -i -D

su - <user>

psql
Password:
psql: pqReadData() -- backend closed the channel unexpectedly.
        This probably means the backend terminated abnormally
        before or while processing the request.
psql
psql: connectDBStart() -- connect() failed: No such file or directory
        Is the postmaster running at 'localhost'
        and accepting connections on Unix socket '5432'?
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Comment: in this way, a user can kill postmaster. It seems, that
the problem concerns only one database.