Can PostgreSQL be embedded?
PostgreSQL is designed as a client/server architecture, which requires separate processes for each client and server, and various helper processes. Many embedded architectures can support such requirements. However, if your embedded architecture requires the database server to run inside the application process, you cannot use Postgres and should select a lighter-weight database solution.
Popular embeddable options include SQLite and Firebird SQL.
적당하지 않다는 얘기로 보입니다만. 그래도 정답이 아닐수 있으니, 한번 더 구글링 해보세요. ("embedded linux postgresql' 키워드로 구글링해보니 좀 보입니다만)
개인적으로 embeded db 를 고른다면 저 같으면, Firebird 를 택하겠습니다.