How do I tell from within a ruby script whether it has been run from the command line or from a non-interactive process?

How do I tell from within a ruby script whether it has been run from the command line, i.e. like this:

> ruby myscript.rb

or from a non-interactive process, e.g. cron?开发者_JAVA技巧

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$stdin.tty? will return true if connected to a terminal otherwise false.

There is a fair bit of additional information on question Best practices with STDIN in Ruby?