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    <p>You probably want to use an SSH library like <a href="https://pypi.python.org/pypi/paramiko" rel="nofollow"><code>paramiko</code></a> (or <a href="https://pypi.python.org/pypi/spur" rel="nofollow"><code>spur</code></a>, <a href="https://pypi.python.org/pypi/Fabric" rel="nofollow">Fabric</a>, etc.… just google/PyPI/SO-search for "Python SSH" to see all the options and pick the one that best matches your use case). There are demos included with <code>paramiko</code> that do exactly what you want to do.</p> <p>If you insist on scripting the command-line <code>ssh</code> tool, you (a) almost certainly want to use <code>subprocess</code> instead of <code>os.system</code> (as the <code>os.system</code> docs explicitly say), and (b) will need to do some bash-scripting (assuming the remote side is running bash) to pass the value back to you (e.g., wrap it in a one-liner script that prints the exit status on <code>stderr</code>).</p> <p>If you just want to know why your existing code doesn't work, let's take a look at it:</p> <pre><code>os.system("ssh -qt hostname 'sudo yum list updates --security &gt; /tmp/yum_update_packagelist.txt';echo $?") </code></pre> <p>First, you're running an <code>ssh</code> command, then a separate <code>echo $?</code> command, which will echo the exit status of <code>ssh</code>. If you wanted to echo the status of the <code>sudo</code>, you need to get the semicolon into the <code>ssh</code> command. (And if you wanted the status of the <code>yum</code>, inside the <code>sudo</code>.)</p> <p>Second, <a href="http://docs.python.org/2/library/os.html#os.system" rel="nofollow"><code>os.system</code></a> doesn't look at what gets printed to <code>stdout</code> anyway. As the docs clearly say, "the return value is the exit status of the process". So, you're getting back the exit status of the <code>echo</code> command, which is pretty much guaranteed to be 0.'</p> <p>So, to make this work, you'd need to get the echo into the right place, and then read the stdout by using <code>subprocess.check_output</code> or similar instead of <code>os.system</code>, and then parse that output to read the last line. If you do all that, it should work. But again, you shouldn't do all that; just use <code>paramiko</code> or another SSH library.</p>
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    1. COYou're wrong about the echo. It's in the right place. It executes the yum command, then echo's the status of the yum command, since it echo's whatever is immediately preceding it on the remote system. I verified that multiple times during my trial and error guessing. The issue was never that I wasn't getting the right exit code, it was that I couldn't find a way to get that exit code into a variable on the local system.
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      1. USKris Griebe
    2. COAnywho, I decided to use the SSH module (uses the paramiko library as you suggested) to do this and have it working now.
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      1. USKris Griebe
    3. CONo, the `echo $?` is not running on the remote system. You can see this by just changing it to, e.g., `echo $HOSTNAME`—it will print the hostname of your machine, not the remote system. The reason it seems to work is that in most cases, the exit status of `ssh` is the exit status of the remote command. But it's very important to understand the difference when you're using `ssh` and `sudo`; if you don't know what's part of what command, you are going to run into serious problems (possibly involving gaping security holes) at some point.
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