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POPython - pipelining subprocess in Windows
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  1. POPython - pipelining subprocess in Windows
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    copied!<p>I'm using Windows 7, and I've tried this under Python 2.6.6 and Python 3.2.</p> <p>So I'm trying to call this command line from Python:</p> <pre><code>netstat -ano | find ":80" </code></pre> <p>under Windows cmd, this line works perfectly fine.</p> <p>So,</p> <ul> <li><p>1st attempt:</p> <pre><code>output = subprocess.Popen( [r'netstat -ano | find ":80"'], stdout=subprocess.PIPE, shell=True ).communicate() </code></pre> <p>An error is raised that 'find' actually didn't receive correct parameter (e.g. 'find ":80" \'):</p> <pre><code>Access denied - \ </code></pre></li> <li><p>2nd attempt:</p> <pre><code>#calling netstat cmd_netstat = subprocess.Popen( ['netstat','-ano'], stdout = subprocess.PIPE ) #pipelining netstat result into find cmd_find = subprocess.Popen( ['find','":80"'], stdin = cmd_netstat.stdout, stdout = subprocess.PIPE ) </code></pre> <p>Again, the same error is raised.</p> <pre><code>Access denied - \ </code></pre></li> </ul> <p>What did I do wrong? :(</p> <p>EDIT:</p> <ul> <li><p>3rd attempt (As @Pavel Repin suggested):</p> <pre><code>cmd_netstat = subprocess.Popen( ['cmd.exe', '-c', 'netstat -ano | find ":80"'], stdout=subprocess.PIPE ).communicate() </code></pre> <p>Unfortunately, subprocess with ['cmd.exe','-c'] results in something resembling deadlock or a blank cmd window. I assume '-c' is ignored by cmd, resulting in communicate() waiting indefinitely for cmd termination. Since this is Windows, my bet bet is cmd only accepts parameter starting with slash (/). So I substituted '-c' with '/c':</p> <pre><code>cmd_netstat = subprocess.Popen( ['cmd.exe', '/c', 'netstat -ano | find ":80"'], stdout=subprocess.PIPE ).communicate() </code></pre> <p>And...back to the same error:</p> <pre><code>Access denied - \ </code></pre></li> </ul> <p>EDIT: I gave up, I'll just process the string returned by 'netstat -ano' in Python. Might this be a bug?</p>
 

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