pg_dumpall fails in cronjob

Hi all,

I have a stange problem when executing pg_dumpall as a cron job.

The crontab entry looks like:
05 22 *  *  1-5 postgres /usr/bin/pg_dumpall -D >
/disks/postgres/db.pg_dumpall

On stderr I get the message
connected to template1...
/usr/bin/pg_dumpall: 0: Bad file descriptor

The createt dumpfile looks like:
--
-- pg_dumpall (7.2)   -D
--
\connect template1
DELETE FROM pg_shadow WHERE usesysid <> (SELECT datdba FROM pg_database
WHERE datname = 'template0');

CREATE USER "werner" WITH SYSID 100 CREATEDB CREATEUSER;
CREATE USER ....                // more users

DELETE FROM pg_group;

There are no further lines in here.

When calling
# /disks/postgres/db.pg_dumpall -D > /disks/postgres/db.pg_dumpall'
manually as user postgres the dumpfile continues like:

--
-- Database alc
--
\connect template1 werner
CREATE DATABASE "alc" WITH TEMPLATE = template0 ENCODING = 'SQL_ASCII';
etc.
etc.

What is the reason for this strange behaviour?
I'm using PostgreSQL 7.2