How do I execute a program from Python? os.system fails due to spaces in path


Question

I have a Python script that needs to execute an external program, but for some reason fails.

If I have the following script:

import os;
os.system("C:\\Temp\\a b c\\Notepad.exe");
raw_input();

Then it fails with the following error:

'C:\Temp\a' is not recognized as an internal or external command, operable program or batch file.

If I escape the program with quotes:

import os;
os.system('"C:\\Temp\\a b c\\Notepad.exe"');
raw_input();

Then it works. However, if I add a parameter, it stops working again:

import os;
os.system('"C:\\Temp\\a b c\\Notepad.exe" "C:\\test.txt"');
raw_input();

What is the right way to execute a program and wait for it to complete? I do not need to read output from it, as it is a visual program that does a job and then just exits, but I need to wait for it to complete.

Also note, moving the program to a non-spaced path is not an option either.


This does not work either:

import os;
os.system("'C:\\Temp\\a b c\\Notepad.exe'");
raw_input();

Note the swapped single/double quotes.

With or without a parameter to Notepad here, it fails with the error message

The filename, directory name, or volume label syntax is incorrect.

1
256
1/17/2018 8:22:09 PM

Accepted Answer

subprocess.call will avoid problems with having to deal with quoting conventions of various shells. It accepts a list, rather than a string, so arguments are more easily delimited. i.e.

import subprocess
subprocess.call(['C:\\Temp\\a b c\\Notepad.exe', 'C:\\test.txt'])
279
12/19/2012 12:07:39 PM

Here's a different way of doing it.

If you're using Windows the following acts like double-clicking the file in Explorer, or giving the file name as an argument to the DOS "start" command: the file is opened with whatever application (if any) its extension is associated with.

filepath = 'textfile.txt'
import os
os.startfile(filepath)

Example:

import os
os.startfile('textfile.txt')

This will open textfile.txt with Notepad if Notepad is associated with .txt files.


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