Can we add one set of variables of process to another process in same Linux machine

Question

I have been working on configuring the postgressql pod and secrets fetching from aws secret manager and kept in one pod volume mount using init container. But while calling pg_ctl -D logfile start command its not recognizing the username & passwords.

Any other approach that we can follow

Tried to source the file within same process but its stating you must specify the POSTGRES_PASSWORD to non-empty value