I am using sqlite3 in a linux machine and I am getting the database without username and password. Can I set a username and password for the same?
SQLite is mainly an embedded database engine, not intended to be used as a multi-user database server that would require usernames and passwords.
You can always encrypt the database file with some user-provided password/-phrase, I guess. But expecting an embedded DBMS to sport full-blown access control is too much.