Off topic:Change column content with shell scripting

Question

[Fluorine]

Here is my problem; I have a spreedsheet (.txt) with 20 columns, for one column named ''xyz'' I want to change its content so if there is for example: aaa or bbb or ccc in the column field - I want to change it to ABC; if the field contains KFL or TST - i want to change it to KTTS etc.

How can I do that with shell scripting?

Thank you!!