Python: How to create a unique file name?

Question

I have a python web form with two options - File upload and textarea. I need to take the values from each and pass them to another command-line program. I can easily pass the file name with file upload options, but I am not sure how to pass the value of the textarea.

I think what I need to do is:

1. Generate a unique file name
2. Create a temporary file with that name in the working directory
3. Save the values passed from textarea into the temporary file
4. Execute the commandline program from inside my python module and pass it the name of the temporary file

I am not sure how to generate a unique file name. Can anybody give me some tips on how to generate a unique file name? Any algorithms, suggestions, and lines of code are appreciated.

Thanks for your concern

Answer 1

I didn't think your question was very clear, but if all you need is a unique file name...

import uuid  unique_filename = str(uuid.uuid4()) 

Answer 2

If you want to make temporary files in Python, there's a module called tempfile in Python's standard libraries. If you want to launch other programs to operate on the file, use tempfile.mkstemp() to create files, and os.fdopen() to access the file descriptors that mkstemp() gives you.

Incidentally, you say you're running commands from a Python program? You should almost certainly be using the subprocess module.

So you can quite merrily write code that looks like:

import subprocess import tempfile import os  (fd, filename) = tempfile.mkstemp() try:     tfile = os.fdopen(fd, "w")     tfile.write("Hello, world!\n")     tfile.close()     subprocess.Popen(["/bin/cat", filename]).wait()         finally:     os.remove(filename) 

Running that, you should find that the cat command worked perfectly well, but the temporary file was deleted in the finally block. Be aware that you have to delete the temporary file that mkstemp() returns yourself - the library has no way of knowing when you're done with it!

(Edit: I had presumed that NamedTemporaryFile did exactly what you're after, but that might not be so convenient - the file gets deleted immediately when the temp file object is closed, and having other processes open the file before you've closed it won't work on some platforms, notably Windows. Sorry, fail on my part.)