Output a variable to screen/file

Hello,

Following is a pl / sql script example, want I want to do is output the variable l_var1 to a file.
How can I do that ? (spooling?)

Thanx

DECLARE
   l_var1 VARCHAR2(2000);

BEGIN       l_var1 := 'This line must be in my file'; Received on Tue Dec 08 1998 - 04:42:56 CST