Temporary files and folders in Ruby

If you’ve been using Ruby for a while, you’ve likely come across Tempfile in your projects. In short, it creates a temporary file in the system’s /tmp directory. From there, you can pass it as an argument to other methods just like a regular file (I mostly see this used in image manipulation gems like mini_magick). If you pass a block, the file is automatically deleted after execution. If not, you’ll need to close and unlink it manually. Keep in mind that Tempfile.create returns an instance of File, not Tempfile. What you might have missed is that Ruby also provides Dir.mktmpdir, which creates a temporary directory (also in /tmp). This is especially useful when writing integration tests where you need to generate multiple temporary files for downstream steps. Dir.mktmpdir returns the path to the temporary folder, allowing you to create files inside it using standard methods like File.write.

Do you use temporary files and directories in your projects? In what scenarios has this feature been most helpful?

require 'tempfile'

f = Tempfile.create
f.write('Some text')
f.flush
f.path # "/tmp/20261007-238355-ug95xp"
f.close
File.unlink(f)

Tempfile.create do |f|
  f.sync = true
  f.write('Some text')

  # work with file
end


require 'tmpdir'

dir = Dir.mktmpdir
f = File.join(dir, 'f.txt') # /tmp/d20261007-457697-nj2gb8/f.txt
File.write(f, 'Some data')
FileUtils.remove_entry(dir)

Dir.mktmpdir do |dir|
  f = File.join(dir, 'f.txt')
  File.write(f, 'Some data')

  # work with file and folder
end