Script for automated modification of .csv file (Ubuntu / Linux Mint)

I export data as a .csv file to import it somewhere else. In between I have to delete most of the columns and rearrange the remaining ones. One of the columns contains prices which have to be reformatted to contain two decimal digits. I'd like to do all this with as few clicks as possible. A script which modifies all .csv files located in the same folder as the script would be nice. Script must run on Ubuntu / Mint - not Windows!