Datafoundry fixed-width ingestion provides an option to append new columns which are extracted from a "match regex" and "extract regex" applied from the filename.
As an example, we are appending a new column during file ingestion based on the following format of the filename as 'file_YYMMDD-HHMMSS'
Step 1: Configure a file ingestion source and crawl for metadata
Step 2: Click on 'Configure', click 'Edit Schema' tab, click on add column and check on 'Extract from filename'
Step 3: Name the column as you wish, select column as 'timestamp', for option specify the format for the timestamp.
Example: yyyy-MM-dd hh:mm:ss