Python: How to create a unique file name?

Solution 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())

Solution 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.)

Solution 3:

The uuid module would be a good choice, I prefer to use uuid.uuid4().hex as random filename because it will return a hex string without dashes.

import uuid
filename = uuid.uuid4().hex

The outputs should like this:

>>> import uuid
>>> uuid.uuid()
UUID('20818854-3564-415c-9edc-9262fbb54c82')
>>> str(uuid.uuid4())
'f705a69a-8e98-442b-bd2e-9de010132dc4'
>>> uuid.uuid4().hex
'5ad02dfb08a04d889e3aa9545985e304'  # <-- this one

Solution 4:

Maybe you need unique temporary file?

import tempfile

f = tempfile.NamedTemporaryFile(mode='w+b', delete=False)

print f.name
f.close()

f is opened file. delete=False means do not delete file after closing.

If you need control over the name of the file, there are optional prefix=... and suffix=... arguments that take strings. See https://docs.python.org/3/library/tempfile.html.

Solution 5:

You can use the datetime module

import datetime
uniq_filename = str(datetime.datetime.now().date()) + '_' + str(datetime.datetime.now().time()).replace(':', '.')

Note that: I am using replace since the colons are not allowed in filenames in many operating systems.

That's it, this will give you a unique filename every single time.