The attached patch adds an \into meta command to store results of preceding SELECTs into pgbench variables, so that they can be reused afterwards.
The feature is useful to make more realistic scripts, currently pgbench script cannot really interact with the database as results are discarded.
The chosen syntax is easy to understand and the implementation is quite light, with minimal impact on the code base. I think that this is a reasonnable compromise.
The SELECTs must yield exactly one row, the number of variables must be less than the number of columns.
Also attached a set of test scripts, especially to trigger various error cases.
Why you are introducing \into and not \gset like psql does?