In Ruby CSV, how to write a blank ,, instead of ,"", to a file?

And If you need new empty line just add double nils like: [nil, nil]

Use

data = ["column one",nil,"column three"]

which generates that CSV

first,second,third
column one,,column three

Ruby 2.6 has quote_empty parameter for the constructor, which can be set to false.

:quote_empty

    When setting a true value, CSV will quote empty values with double quotes. When false, CSV will emit an empty string for an empty field value.