Write to a file atomically. Useful for situations where you don‘t want other processes or threads to see half-written files.

 File.atomic_write("important.file") do |file|
   file.write("hello")
 end

If your temp directory is not on the same filesystem as the file you‘re trying to write, you can provide a different temporary directory.

File.atomic_write("/data/something.imporant", "/data/tmp") do |f|

  file.write("hello")

end

[Source]

    # File vendor/rails/activesupport/lib/active_support/core_ext/file.rb, line 16
16: def File.atomic_write(file_name, temp_dir = Dir.tmpdir)
17:   temp_file = Tempfile.new(File.basename(file_name), temp_dir)
18:   yield temp_file
19:   temp_file.close
20:   File.rename(temp_file.path, file_name)
21: end