re = /(?<=^\d+ +\w*)\w{3,}/m
str = '820384318 05555946 268 859
820384456 0PM45276 268 859
820384755 KPM53246 268 859 '
# Print the match result
str.scan(re) do |match|
puts match.to_s
end
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html