Re: import subprocess

Matt,

 

I had the same problem and ended up solving it by using System.Diagnostics.Process instead of subprocess.  As far as I know, subprocess doesn't work under IronPython.  I don't remember all of the reasons as to why it doesn't work, but, for example, os.pipe doesn't exist under IronPython like in CPython.

 

Unfortunately, it's a bit of extra work if you're using subprocess to capture stdout, stdin, etc.  Here's a snippet of some code I used for this.  It’s not very straightforward, unfortunately, because I wanted to combine the stdout/stderr streams.  Also, the only way to run a command like you would type it on the command line is to run it through cmd.exe.  You can search around for it, getting return values can be a real pain as well.  I didn’t test this code, just tried to copy and paste the important parts from what I have, so I may have forgotten something.

 

class Process :

    def __init__( self ):

  self.stdoutstderr = System.IO.StringWriter()

  self.cmdLine = "rd /s /q ."

 

    def Run( self ):

        processStartInfo = System.Diagnostics.ProcessStartInfo( "cmd", "/c " + self.cmdLine )

        processStartInfo.UseShellExecute = False

        processStartInfo.RedirectStandardInput = True

        processStartInfo.RedirectStandardOutput = True

        processStartInfo.RedirectStandardError = True

        processStartInfo.CreateNoWindow = True

        processStartInfo.EnvironmentVariables.Clear()

        for envVariable in os.environ.keys() :

            processStartInfo.EnvironmentVariables.Add( envVariable, os.environ[ envVariable ] )

        processToRun = System.Diagnostics.Process()

        processToRun.StartInfo = processStartInfo

        processToRun.OutputDataReceived += self.__WriteStdoutData

        processToRun.ErrorDataReceived += self.__WriteStderrData

        processToRun.Start()

        processToRun.BeginOutputReadLine()

        processToRun.BeginErrorReadLine()

        processToRun.WaitForExit()

 

        stdoutstderrReader = System.IO.StringReader( self.stdoutstderr.ToString() )

        return ( processToRun.StandardInput, stdoutstderrReader )

 

    def __WriteStdoutData ( self, sendingProcess, stdoutData ) :

        if stdoutData.Data != None:

            self.stdoutstderr.Write( stdoutData.Data + '\n' )

 

    def __WriteStderrData ( self, sendingProcess, stderrData ) :

        if stderrData.Data != None:

            self.stdoutstderr.Write( stderrData.Data + '\n' )

 

Hopefully that helps.

 

Eric

 

-----Original Message-----
From: users-bounces@... [mailto:users-bounces@...] On Behalf Of Matthew S Bourdua
Sent: Thursday, July 05, 2007 3:50 PM
To: users@...
Subject: [IronPython] import subprocess

 

Hello,

 

I have a question about the "subprocess" module.  I am unable to "import

subprocess" in my scripts.  Will IronPython will support this in the future,

or, perhaps is it intentionally not supported?  (Or perhaps I am doing

something stupid, and it should work?)

 

I recently began using IronPython because I had both Python scripts and .Net

classes that I needed to use together.  So far I have been pretty pleased

with how well everything is working.

 

My biggest problem has been that the os.system() call does not work in

IronPython.  I notice that this was raised as an issue in Sep '06

(http://www.codeplex.com/IronPython/WorkItem/View.aspx?WorkItemId=2982). 

While hunting around for an alternative, I found the following text in the

library reference (http://docs.python.org/lib/module-subprocess.html):

 

"The subprocess module ... intends to replace several other, older modules

and functions, such as:

 

os.system

os.spawn*

os.popen*

popen2.*

commands.*"

 

For this reason, I thought that perhaps "os.system" was going to become

deprecated in favor of "subprocess", and that might explain why this issue

has not been addressed.

 

However, I am unable to "import subprocess" in IronPython.  When I do so, an

exception is raised because, "No module named fcntl".  Digging into this a

bit, I notice the following variable defined within subprocess.py (this is

from ActivePython 2.5):

 

mswindows = (sys.platform == "win32")

 

And then many conditional statements of the form:

if mswindows:

...#Windows specific code

else

...#Non-windows code, presumably

 

IronPython fails this check because sys.platform = 'cli', and thus is lead

into using modules that are (I would guess) meant for Unix-based systems.

 

Further, this behavior seems to be known - I noticed that this seemed to be

accounted for in (what appears to be) the automatic test-suite code located

here:

http://www.codeplex.com/IronPython/SourceControl/FileView.aspx?itemId=296023

&changeSetId=21805

 

What's strange to me is that I couldn't find a single reference to using

subprocess in IronPython anywhere.  So perhaps this issue is widely

understood by everybody but me (I'm relatively new to Python), or simply not

an issue for anybody but me?

 

Anyway, I was hoping somebody on this mailing list might have some insight

to share.

 

Thanks,

Matt

 

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