filesystem/file_for_descriptor_no_parens.rb

tests/_examples/filesystem/file_for_descriptor_no_parens.rb in the metorex repository.

# File.for_fd with no mode uses the descriptor the way it was opened.
path = "/tmp/metorex_file_for_descriptor_#{Process.pid}.txt"
opened = File.open path, "w+"
adopted = File.for_fd opened.fileno
adopted.autoclose = false
p adopted.write("written through the descriptor")
adopted.close
opened.close
p File.read path
File.delete path

Output:

30
"written through the descriptor"