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<h1>Linux process management !</h1>
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<span id="author" class="author">Apostolos rootApostolos@swarmlab.io</span><br>
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<div id="toctitle">Table of contents</div>
<ul class="sectlevel1">
<li><a href="#_process">1. process</a></li>
<li><a href="#_linux_process_management">2. Linux process management</a></li>
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<div class="sect1">
<h2 id="_process">1. process</h2>
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<p>An instance of a running program is called a process.
Every time you run a shell command, a program is run and a process is created for it.</p>
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<p>In any modern operating system there can be more than one instance of a program loaded in memory at the same time.</p>
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<div class="sect1">
<h2 id="_linux_process_management">2. Linux process management</h2>
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<div class="paragraph">
<p>Operating systems need some ways to create processes.</p>
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<ul>
<li>
<p>In a very simple system designed for running only a single application (e.g., the controller in a microwave oven), it may be possible to have all the processes that will ever be needed be present when the system comes up.</p>
</li>
<li>
<p>In general-purpose systems, however, some way is needed to create and terminate processes as needed during operation.</p>
</li>
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<p><strong>There are four principal events that cause a process to be created:</strong></p>
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<ul>
<li>
<p>System initialization.</p>
</li>
<li>
<p>Execution of process creation system call by a running process.</p>
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<li>
<p>A user request to create a new process.</p>
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<li>
<p>Initiation of a batch job.</p>
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</ul>
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<p>Process creation in UNIX and Linux are done through <strong>fork()</strong> or <strong>clone()</strong> system calls.</p>
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<p>There are several steps involved in process creation.</p>
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<ul>
<li>
<p>process scheduling,</p>
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<li>
<p>interrupt handling,</p>
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<p>signaling,</p>
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<p>process prioritization,</p>
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<p>process switching,</p>
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<p>process state,</p>
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<p>process memory</p>
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