/usr/bin/rotp is in ruby-rotp 2.1.1+dfsg-1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 | #!/usr/bin/ruby
$: << File.expand_path('../../lib', __FILE__)
require 'rotp'
require 'rotp/cli'
ROTP::CLI.new(File.basename(__FILE__), ARGV).run
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