Create unique file name and fetching it to commandline argument

Question

Hi everyone,

I am working on python right now and i am little bit stuck in performing some tricks. I have web form with two options- File upload and textarea, i can easily pass file name with file upload options but have problem when it's textarea. Because when i use textarea then first i have to save values passed from textarea to some files and save it on the working directory. After that i can execute commandline argument and pass same saved filename name. For this problem i have to generate unique file first and save the values passed from textarea in it.

Can anybody give me some tips to solve my problem. 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 = 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.)