Usage: ruby reverse_tsv.rb <tsv> [<offset>]

reverse_tsv.rb

#!/usr/bin/env ruby

require "csv"

path = ARGV[0]
offset = ARGV[1] ? ARGV[1].to_i : 1

opts = {}
opts[:col_sep] = "\t" if path.end_with?(".tsv")
rows = CSV.read(ARGV[0], opts)

s = CSV.generate(col_sep: "\t") do |csv|
  rows.each do |row|
    new_row = []
    offset.times do
      new_row << row.shift
    end
    new_row += row.reverse
    csv << new_row
  end
end

print s