System new line separator in Ruby

Question

How can I determine new line separator used by OS (LF, CR/LF or other), in Ruby?

Answer 1

You shouldn't need to. In your case, I think you can just use FileUtils.

Answer 2

File.open("some_temporary_file", "w") { |file| file.puts }
new_line_separator =
  File.open("some_temporary_file", "rb") { |file| file.read }

Answer 3

Not sure if there is a direct solution to get the type of newline based on OS, but there is the $/ variable that holds the "input record separator". By default this will be "\n". (Documentation here)

You can detect the OS and then set $/ to the "correct" value.

To detect OS:

puts RUBY_PLATFORM                  # => 'i386-linux'
require 'rbconfig'
puts Config::CONFIG['target_cpu']   # => 'i386'
puts Config::CONFIG['target_os']    # => 'linux'
puts Config::CONFIG['host_cpu']     # => 'i686'
puts Config::CONFIG['host_os']      # => 'linux-gnu'

Also remember that when reading files, they could have a mix of various line separators - for example if a text file was edited in both Windows and Linux. Thus if you're processing files, do not depend on the "OS line seperator" exclusively.