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PONot receiving SIGCHLD for processes executed with sudo
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copied!<p>I'm currently in the process of writing a shell. I execute processes and utilize a <code>SIGCHLD</code> signal handler to clean up (wait on them) when they are complete.</p> <p>Everything has been working -- except when I execute processes which escalate privileges with <code>sudo</code>. In these cases, I never get a <code>SIGCHLD</code> signal -- so I never know that the process has completed executing.</p> <p>When I receive a command such as <code>sudo ls</code>, I execute the program <code>sudo</code> and then provide <code>ls</code> as a parameter. I perform this execution with <code>execvp</code>.</p> <p>If I take a look at <code>ps -aux</code> after my shell has executed <code>sudo ls</code>, I see the following:</p> <pre><code>root 4795 0.0 0.0 4496 1160 pts/29 S+ 16:51 0:00 sudo ls root 4796 0.0 0.0 0 0 pts/29 Z+ 16:51 0:00 [ls] <defunct> </code></pre> <p>So, <code>sudo</code> ran and got assigned <code>pid = 4795</code>, with the child (ls) being assigned <code>4796</code>. The child has completed its task and is now sitting in a zombie state. <code>sudo</code> doesn't seem to want to reap the zombie process and just sits there.</p> <p>I would like to know what is causing this behavior -- I've tried different techniques to cleanup these zombie processes, such as running my shell under <code>sudo</code> and waiting directly on <code>sudo</code> and the <code>PID</code> which <code>sudo</code> executes (4796 in the above example). None of these techniques have worked.</p> <p>As always, any advise is appreciated.</p>

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