What does #tty? on STDIN mean / do in ruby?

Question

Reading the ruby docs isn't overly helpful here:

Returns true if ios is associated with a terminal device (tty), false otherwise.

I was hoping to get some additional resources or explanation to help me understand this better.

For context, I'm writing a little command line program that accepts either a file path or piped content into the ruby executable and am using #tty? to determine what is coming in.

Answer 1

Seems like http://www.jstorimer.com/blogs/workingwithcode/7766125-writing-ruby-scripts-that-respect-pipelines supplies the most concise description of what #tty? does:

Ruby's IO#isatty method (aliased as IO#tty?) will tell you whether or not the IO in question is attached to a terminal. Calling it on $stdout, for instance, when it's being piped will return false.

Here is some relevant info that you may find useful:

• Detecting stdin content in Ruby
• How can you check for STDIN input in a Ruby script?
• https://stackoverflow.com/a/273605
• https://gist.github.com/timuruski/6072363

Background meaning via What do pty and tty mean?:

In UNIX, /dev/tty* is any device that acts like a "teletype", ie, terminal. (Called teletype because that's what we had for terminals in those benighted days.)

In the spirit of the question, here's an example of writing to /dev/tty from http://zetcode.com/lang/rubytutorial/io/:

#!/usr/bin/ruby

fd = IO.sysopen "/dev/tty", "w"
ios = IO.new(fd, "w")
ios.puts "ZetCode"
ios.close