perl DBI/postgres: alternatives to slash commands?

There was a thread on similar topic
http://groups.google.com/group/comp.databases.postgresql.novice/browse_thread/thread/18b7fab2c5961432/92b69e856087b780?q=slash&rnum=9#92b69e856087b780
but I didn't find answer to the problem --

The Postgres slash commands are not supported by perl DBI (like to show
databases, etc.). Wonder are there standard SQL in Postgres to perform
the same jobs for those slash commands? (like in Oracle "select
table_name from user_tables" for "\dt", etc.). Or other alternatives
to get around this?

Thanks in advance.

Joe

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