How to insert a record in fixed width flatfile

I have a fixed width flatfile with 5 columns, i will load file from oracle database to the flatfile for every 15 min at the end of the file, i want to insert a record by calling a shell script for inserting a record.

please can any one help me.

Thanks.

After the flat file is created, use something like this:

echo 'whatever you need to add' >> yourflatfile