Question

I am working on a program that will find some files and provide the file information to a NSIS script. The NSIS script accepts the command line as follows

makensis.exe /DON="This is one" /DOD="c:\path1\path2 to dir\path 3" scriptfile.nsi

The values of the switches will change on each execution of the program. I have tried to get this to execute using subprocess.call and subprocess.Popen. The issue I am having has to do with quoting.

First of all the subprocess calls seem to put the entire argument statement between double quotes making NSIS see them as one argument. Second I am having some difficulty getting the individual switches properly quoted on the command line. Here is a snippet of what my program currently looks like.

subprocess.Popen([setup.profile['NSISExe'], ' /DON="' + setup.profile['DESC'] + '" /DOD="' + setup.profile['InstallDir'] + \
   '" /DMT="' + app.machine_type.get() + '" /DSD="' + os.path.join(WinShellVar.LOCAL_APPDATA, 'MLC CAD', appname) + \
   '" /DXV=X6 ' + setup.profile['NSISScript']])

And here is the output from NSIS

    Can't open script " /DON="Mastercam X6 Standard" /DOD="C:\Users\John\Desktop" /D
MT="mill" /DSD="C:\Users\John\AppData\Local\MLC CAD\mcdeftool" /DXV=X6 bin\packa
ge.002.nsi"

As you can see I am using a mixed bag of data, getting some bits for dicts and some from class calls (be easy on me if my terms are somewhat incorrect, I have been learning python for about 4 days now, correct me please just nicely). If using this data like this is “unpythonic” let me know.

Looking forward to your input

Answer 1

disclaimer — I don’t use windows

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I think you probably want something like:

subprocess.Popen([setup.profile['NSISExe'], '/DON=' + setup.profile['DESC'],
                  '/DOD=' + setup.profile['InstallDir'],
                  '/DMT=' + app.machine_type.get(),
                  '/DSD=' + os.path.join(WinShellVar.LOCAL_APPDATA, 'MLC CAD', appname), 
                  '/DXV=X6',
                  setup.profile['NSISScript']])

When the shell reads the commandline, it splits on non-quoted, non-escaped whitespace. When you pass a list to Popen, it expects the list elements to be the way it would look after the shell split the arguments. The other option is to pass a string (instead of a list) exactly as you would put it into the windows shell and pass shell=True to Popen. But that method isn’t preferred as it is much more vulnerable to shell-injection insecurities.