Ruby Error

#This is a piece of code that belongs to a program under development
print "Extension: "
ext = gets.chomp

puts Dir.glob ['*.#{ext}'] #This part is missing something
=begin
Although the program knows it's value it won't do what it's supposed to.
It's suppose to display files of given extension on current directory.
txt for text files
=end
else puts "Unknown command: #{command}"
end