Dumping pg_shadow and pg_database as SQL using pg_dump

I'd like to save the list of users, groups, and databases regularly to a
separate file (just in case). The output of pg_dumpall suffices for my need:

=================================
DELETE FROM pg_shadow WHERE usesysid <> (SELECT datdba FROM pg_database
WHERE datname = 'template0');
CREATE USER ... WITH SYSID ... PASSWORD '...' NOCREATEDB NOCREATEUSER;
...

DELETE FROM pg_group;
...

CREATE DATABASE ... WITH OWNER = ... TEMPLATE = ... ENCODING = '...';
...
=================================

But can I get these with pg_dump?

--
dave