How to query by column names - Mailing list pgsql-sql

This may be a simple but can I create a query such as

select (select attname from pg_attribute where attrelid = (select 
relfilenode from pg_class where relname = 't1') and attisdropped = 
false and attnum > 0) from t1;

I get
ERROR:  more than one row returned by a subquery used as an expression

Thanks
Richard