Shell script that starts sqlplus utility and executes a query, gathers output

I'm trying to do this: In sample.sh: #!/bin/bash sqlplus / as sysdba select * from dual; And just when I run this shell script, it opens sqlplus utility, but it cannot execute the next line that I have written. When I manually exit out of sqlplus, only then the shell executes the remaining line and I get error message saying 'Select * from dual' is not a valid command. How can I make the script execute the SQL text *within* the context of sqlplus?