Can ruby tell if it is called from an interactive shell or cron?

Question

When I run a rake task by hand, I want to make Rails.logger log to STDOUT. But not if the rake task is run by a cron job. Is there a way to find out, how the rake task got started?

task :my_env => :environment do
  if A_USER_IS_WATCHING_ME
    Rails.logger = Logger.new(STDOUT)
    ActiveRecord::Base.logger = Logger.new(STDOUT)
  end
end

Answer 1

$stdout.tty? returns true if $stdout is associated with a terminal device (i.e. an interactive user) and false otherwise:

# test.rb
if $stdout.tty?
  puts "tty"
else
  puts "not a tty"
end

From bash:

$ ruby test.rb
tty

$ ruby test.rb > test.log
$ cat test.log
not a tty