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    <p>OPTION 1: You can re-use a ssh process by redirecting input using a PIPE. </p> <p>Here is a basic example:</p> <pre><code>[(Z) &lt;/tmp&gt; ]% touch input_file [(Z) &lt;/tmp&gt; ]% tailf input_file | ssh &lt;remote_host&gt; </code></pre> <p>Now try writing something into the file</p> <pre><code>[(Z) &lt;/tmp&gt; ]% echo "date" &gt;&gt; /tmp/input_file </code></pre> <p>Here is a way to make use of this in Python using subprocess module.</p> <pre><code>import subprocess SSH_CMD = "cat -| /usr/bin/ssh -o PasswordAuthentication=no -T -x %s " HOSTNAME = "127.0.0.1" s = subprocess.Popen(SSH_CMD%HOSTNAME , shell=True, close_fds=True, stdin=subprocess.PIPE, stderr=subprocess.PIPE, stdout=subprocess.PIPE) </code></pre> <p>This starts a subprocess which can be re-used. Please note that <code>close_fds=True</code> is required because of a known bug (<a href="http://bugs.python.org/issue2320" rel="nofollow">http://bugs.python.org/issue2320</a>). </p> <pre><code>&gt;&gt;&gt; REMOTE_CMD = "date" &gt;&gt;&gt; s.stdin.write( REMOTE_CMD + ... "\necho 'remote command completed with exit code = '$?\n") &gt;&gt;&gt; s.stdout.readline() 'Thu Feb 16 20:01:36 PST 2012\n' &gt;&gt;&gt; s.stdout.readline() 'remote command completed with exit code = 0\n' </code></pre> <p><code>echo 'remote command completed with exit code = '$?\n</code> line is used to know that the remote command finished and it is done writing to s.stdout. This is also useful to know the exit code of the remote command. </p> <p>To use the same subprocess for executing another remote command:</p> <pre><code>&gt;&gt;&gt; REMOTE_CMD = "uptime" &gt;&gt;&gt; s.stdin.write( REMOTE_CMD + ... "\necho 'remote command completed with exit code = '$?\n") &gt;&gt;&gt; s.stdout.readline() ' 20:02:17 up 28 days, 9:15, 48 users, load average: 0.01, 0.02, 0.05\n' &gt;&gt;&gt; s.stdout.readline() 'remote command completed with exit code = 0\n' </code></pre> <p>Coming back to your question, once you create a ssh subprocess, you can keep sending the remote commands. Once the user is quits, you can kill the subprocess.</p> <pre><code>&gt;&gt;&gt; s.kill() </code></pre> <p>OPTION 2: I have never used this, but ssh has a ControlMaster option for re-using ssh. Check man page for ssh_config(5)</p>
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    1. POCreate and maintain several ssh sessions in Python
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    1. COI'll investigate this as a solution, looks nifty. Thanks for your help, I'll let you know how it works out.
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    2. COhi, using your solution, if I give ls as the remote command, I will not know for how long the pipe will have data. I wish to stop at some point, and then send in the next command..
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    3. COYes, that is correct. To know when to stop doing readline(), you'l have to compare each output line with "remote command completed with exit code = XX" (Note the echo command added after REMOTE_CMD in my original code snippet). It helps me to know the exit_code of the REMOTE_CMD too.. but I agree, this has its disadvantages.
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