what is the use of “#!/usr/local/bin/ruby -w” at the start of a ruby program

Question

what is the use of writing the following command at the start of a ruby program ?

#!/usr/local/bin/ruby -w

Is it OS specific command? Is it

Answer 1

Although the execution behavior of a shebang line does not translate directly to the Windows world, the flags included on that line (for example the -w in your question) do affect the running Ruby script.

Example 1 on a Windows machine:

#!/usr/local/bin/ruby -w
puts $VERBOSE   # true

Example 2 on a Windows machine:

#!/usr/local/bin/ruby
puts $VERBOSE   # false