What is the best way to get an empty temporary directory in Ruby on Rails?

Question

What is the best way to get a temporary directory with nothing in it using Ruby on Rails? I need the API to be cross-platform compatible. The stdlib tmpdir won\'t work.

Answer 1

A general aprox I'm using now:

def in_tmpdir
  path = File.expand_path "#{Dir.tmpdir}/#{Time.now.to_i}#{rand(1000)}/"
  FileUtils.mkdir_p path
  yield path
ensure
  FileUtils.rm_rf( path ) if File.exists?( path )
end

So in your code you can:

in_tmpdir do |tmpdir|
  puts "My tmp dir: #{tmpdir}"
  # work with files in the dir
end

The temporary dir will be removed automatically when your method will finish.

Answer 2

You can use Dir.mktmpdir.

Using a block will get rid of the temporary directory when it closes.

Dir.mktmpdir do |dir|
  File.open("#{dir}/foo", 'w') { |f| f.write('foo') }
end

Or if you need multiple temp directories to exist at the same time, for example

context 'when there are duplicate tasks' do
  it 'raises an DuplicateTask error' do
    begin
      tmp_dir1 = Dir.mktmpdir('foo')
      tmp_dir2 = Dir.mktmpdir('bar')

      File.new("#{tmp_dir1}/task_name", 'w+')
      File.new("#{tmp_dir2}/task_name", 'w+')

      expect { subject.filepath('task_name') }.to raise_error(TaskFinder::DuplicateTask)
    ensure
      FileUtils.remove_entry tmp_dir1
      FileUtils.remove_entry tmp_dir2
    end
  end
end

Dir.mktmpdir creates a temporary directory under Dir.tmpdir (you'll need to require 'tmpdir' to see what that evaluates to).

If you want to use your own path, Dir.mktmpdir takes an optional second argument tmpdir if non-nil value is given. E.g.

Dir.mktmpdir(nil, "/var/tmp") { |dir| "dir is '/var/tmp/d...'" }

Answer 3

The Dir object has a method mktmpdir which creates a temporary directory:

require 'tmpdir' # Not needed if you are using rails.

Dir.mktmpdir do |dir|
  puts "My new temp dir: #{dir}"
end

The temporary directory will be removed after execution of the block.