"\set AUTOCOMMIT off" has affect

Hello!

I want to disable autocommit, my psqlrc:

SET client_min_messages = 'WARNING';
SET add_missing_from = false;
\set AUTOCOMMIT off

it has no effect:

echo "show AUTOCOMMIT" | psql
SET
SET
 autocommit
------------
 on
(1 row)

How can I disable autocommit in psqlrc?

Thanks,
Axel.