LaTeXフォーマットがshift_jisなのでutf8に変換した

brew install nkf
ruby convert_utf8.rb /path/to/source /path/to/dest

convert_utf8.rb

#!/usr/bin/env ruby

if ARGV.size < 2
  STDERR.puts "ruby #{$0.split(/\//).last} /path/to/source /path/to/dest"
  exit 1
end

src = ARGV.shift
dest = ARGV.shift

unless File.exists? src
  STDERR.puts "source directory '#{src}' not exists"
  exit 1
end

Dir.mkdir(dest) unless File.exists? dest

Dir.glob("#{src}/*").each do |file|
  name = file.split(/\//).last
  puts cmd = "nkf -u #{file} > #{dest}/#{name}"
  system cmd
end