ruby脚本gets方法没有接受输入

执行这个脚本的时候，kee=gets.chomp这行代码没有接受输入，请问是怎么回事？谢谢。

#!/usr/bin/ruby

require 'crypt/blowfish'

unless ARGV[0]
    puts "Usage: ruby encrypt.rb "
    puts "Example: ruby encrypt.rb secret.stuff"
    exit
end

filename=ARGV[0].chomp
puts filename
c="Encrypted_#{filename}"
if File.exists?(c)
    puts "File already exists."
    exit
end
print "Enter your encryption key (1-56 bytes): "
kee=gets.chomp
begin
    blowfish=Crypt::Blowfish.new(kee)
    blowfish.encrypt_file(filename.to_str,c)
    puts 'Encryption sucess!'
rescue Exception => e
    puts "An error occurred during encryption: \n #{e}"
end