Ruby automatically deletes temp file?
I'm confused. Here's my code:
require 'csv'
require 'tempfile'
f = Tempfile.new('csv','/tmp')
f.write 'just wanna test'
f.close
p f.path
If I open the output path, it is empty.
I think this is because TempFile is automatically removed from the filesystem every time the ruby session ends. However, how do I know exactly when the file was deleted? Since I am going to use it to create a temporary file in my rails application, I am afraid the file was deleted before using it.
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From the docs:
When the Tempfile object is garbage collected, or when the Ruby interpreter exits, the associated temporary file is automatically deleted.
So, if you have it f
in scope, it will not be removed. If you quit Ruby, it will be removed. If you're still in Ruby but f
out of scope, it is undefined (probably not removed, but not guaranteed to exist and should not be used.)
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The tempfile is removed by garbage collection (it is no longer referenced and cleaning up frees the object).
As stated in the Ruby documentation :
When the Tempfile object is garbage collected, or when the Ruby interpreter exits, the associated temporary file is automatically deleted ...
As long as you have a reference to a temple object, you don't have to worry about deleting it prematurely.
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I saw myself Tempfile
collecting garbage in the same process as I created many temporary files for archiving. In the code below, if I didn't store the descriptors Tempfile
in an array handles
, I would get a runtime ( Errno::ENOENT: No such file or directory @ rb_sysopen
) error when the block is Zip::File.open
closed:
handles = []
Zip::File.open(zip_file.path, Zip::File::CREATE) do |zip|
# there are hundreds of @foos to iterate over
@foos.each do |foo|
cit_filename = generate_some_unique_filename
cit_file = Tempfile.new(cit_filename)
handles << cit_file
cit_file.puts('some text')
cit_file.close
zip.add(cit_filename, cit_file.path)
end
end # <- runtime error would have thrown at this point
handles = nil
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