Spool does not require a semicolon. The semicolon ends the sql buffer to be sent via the CLI to the RDBMS. spool is a sqlplus command, hence no query buffer.

Same comment holds for exit, except, there's no reason to bother with exit anyway. Just use a document. Here's an example from asktom:

#!/bin/csh -f

sqlplus scott/tiger <<EOF
exec dbms_output.put_line( 'Hello' );
EOF
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