Ruby

http://ruby-doc.org/core-2.2.3/Object.html#ARGV

The above documentation states that ARGV[0] will contain the name of the Ruby program. While this is the behavior of ARGV in other places (C, Python, etc), it is not the behavior in Ruby.

In Ruby, ARGV[0] contains the name of the first argument supplied to the program's invocation.

To reproduce:

# argv-tester.rb
#!/usr/bin/env ruby

p ARGV[0]

Then execute with an argument:

$> ruby argv-tester.rb foo
foo

And without an argument:

$> ruby argv-tester.rb
nil