#057 Temporary Files with Ruby

Notes

The Tempfile class in the ruby standard library provides a simple interface for creating and managing temporary files.

File Name Generation

Tempfile provides threadsafe generation of unique filenames, and accepts hints on the base name, path and extension:

Tempfile.new('foo').path
 => "/var/folders/28/_tsmhg4172s_wy7vswfkzq9h0000gn/T/foo20190720-858-2bg33b"
Tempfile.new('foo', '/var/folders/28/_tsmhg4172s_wy7vswfkzq9h0000gn/T').path
 => "/var/folders/28/_tsmhg4172s_wy7vswfkzq9h0000gn/T/foo20190720-858-tp775f"
Tempfile.new(['foo', '.jpg']).path
 => "/var/folders/28/_tsmhg4172s_wy7vswfkzq9h0000gn/T/foo20190720-858-bry74e.jpg"

Cleaning Up Files

Tempfile automatically removes tempfiles after the tempfile handle is out of scope and the garbage collector runs.

Explicitly removing generated files is possible, and probably a good idea if many temp files are being created. This can be performed with unlink, close(true) or close! methods.

If one wants to generate a temp file and prevent it’s automatic removal, one technique is to undefine the finalizer on the tempfile handle: ObjectSpace.undefine_finalizer(file)

Running Some Tests

tempfiles_test.rb demonstrates a number of ways of working with Tempfiles, including implicit and explicit file cleanup approaches.

$ ruby tempfiles_test.rb
Run options: --seed 42461

# Running:

...

Finished in 0.006527s, 459.6146 runs/s, 2451.2778 assertions/s.

3 runs, 16 assertions, 0 failures, 0 errors, 0 skips

Credits and References