Building a parser to use in script (bash)

I need to discovery patterns in a string by bash, I would like put auto-execution with crontab.

I have a string that contain data like %d/%m/%Y %H:%i aaa bbb ccc 123456 ddd 7890 eee and something like that. It's a report.

I thought to define constants like string masks, and compare every substring with my masks. I think I will use a mix with lenght and char positition.

I'm googling to have better idea and watch some other implementation, but I'm not finding useful results.

Any suggestion? Thanks.