Executing sqlldr in form

Control file will have this columns column1, column2, user_name

Test table will have this columns column1, column2, user_name

csv file will have 2 columns column1, column2.

This is the code the creates the control file and loads data to test table. Column1 and column2 are read from the csv file.
Since I am logged in and executing this code in the form and my name need to be inserted to user_name column of the test table.
How do I do that?

Begin

Out_File := CLIENT_TEXT_IO.FOPEN(v_file_ctl, 'W');

line_buf := 'OPTIONS (SKIP = 1) LOAD DATA'||chr(10)||