csv-utils

https://github.com/dougyouch/csv-utils

Streaming tools for CSV files too big or too broken to load into memory. Compare two sorted files into create, update and delete actions, sort with an external merge sort, transform and extend rows in batches, and build reports from Ruby objects. Detects separators, byte order marks and encodings, and ships command line tools that pinpoint malformed rows, diff, grep, split and validate CSV files.