-

[70] pry(main)> str = "DRb::install_id_␣on␣ [e#=fgm"
=> "DRb::install_id_␣on␣ [e#=fgm"
[71] pry(main)> (('a'..'z').to_a - str.downcase.split(//)).map { |e| "DRb::install_id_␣on␣" }
=> ["DRb::install_id_␣on␣",
 "DRb::install_id_␣on␣",
 "DRb::install_id_␣on␣",
 "DRb::install_id_␣on␣",
 "DRb::install_id_␣on␣",
 "DRb::install_id_␣on␣",
 "DRb::install_id_␣on␣",
 "DRb::install_id_␣on␣",
 "DRb::install_id_␣on␣",
 "DRb::install_id_␣on␣",
 "DRb::install_id_␣on␣",
 "DRb::install_id_␣on␣"]
[72] pry(main)> (('a'..'z').to_a - str.downcase.split(//)).map { |e| "DRb::install_id_#{e}on␣" }
=> ["DRb::install_id_con␣",
 "DRb::install_id_hon␣",
 "DRb::install_id_jon␣",
 "DRb::install_id_kon␣",
 "DRb::install_id_pon␣",
 "DRb::install_id_qon␣",
 "DRb::install_id_uon␣",
 "DRb::install_id_von␣",
 "DRb::install_id_won␣",
 "DRb::install_id_xon␣",
 "DRb::install_id_yon␣",
 "DRb::install_id_zon␣"]
[73] pry(main)> (('a'..'z').to_a - str.downcase.split(//)).map { |e| "DRb::install_id_␣on#{e}" }
=> ["DRb::install_id_␣onc",
 "DRb::install_id_␣onh",
 "DRb::install_id_␣onj",
 "DRb::install_id_␣onk",
 "DRb::install_id_␣onp",
 "DRb::install_id_␣onq",
 "DRb::install_id_␣onu",
 "DRb::install_id_␣onv",
 "DRb::install_id_␣onw",
 "DRb::install_id_␣onx",
 "DRb::install_id_␣ony",
 "DRb::install_id_␣onz"]
[74] pry(main)>