Unix code / script in Runtime operation command after message processing

Hi Experts,

My scenario is JDBC to EDI 940, I need to add one source field (ABC) in file name.

Using Runtime operation command after message processing for this requirement, Please send if you have code for this.

Note: I am using PI 7.3 dual stack and used multi mapping and File sender with classifier, BIC and split modules. So can not able to use dynamic configuration / variable substitution.

Looking only for unix script. Please provide unix script / code for adding one source field in file name using Runtime operation command after message processing.

Thank you.