Request UAC elevation from within a Python script?

I want my Python script to copy files on Vista. When I run it from a normal cmd.exe window, no errors are generated, yet the files are NOT copied. If I run cmd.exe "as administator" and then run my script, it works fine.

This makes sense since User Account Control (UAC) normally prevents many file system actions.

Is there a way I can, from within a Python script, invoke a UAC elevation request (those dialogs that say something like "such and such app needs admin access, is this OK?")

If that's not possible, is there a way my script can at least detect that it is not elevated so it can fail gracefully?

Solution

As of 2017, an easy method to achieve this is the following:

import ctypes, sys

def is_admin():
    try:
        return ctypes.windll.shell32.IsUserAnAdmin()
    except:
        return False

if is_admin():
    # Code of your program here
else:
    # Re-run the program with admin rights
    ctypes.windll.shell32.ShellExecuteW(None, "runas", sys.executable, " ".join(sys.argv), None, 1)

If you are using Python 2.x, then you should replace the last line for:

ctypes.windll.shell32.ShellExecuteW(None, u"runas", unicode(sys.executable), unicode(" ".join(sys.argv)), None, 1)

Also note that if you converted you python script into an executable file (using tools like py2exe, cx_freeze, pyinstaller) then you should use sys.argv[1:] instead of sys.argv in the fourth parameter.

Some of the advantages here are:

No external libraries required. It only uses ctypes and sys from standard library.
Works on both Python 2 and Python 3.
There is no need to modify the file resources nor creating a manifest file.
If you don't add code below if/else statement, the code won't ever be executed twice.
You can get the return value of the API call in the last line and take an action if it fails (code <= 32). Check possible return values here.
You can change the display method of the spawned process modifying the sixth parameter.

Documentation for the underlying ShellExecute call is here.