https://vvivid.dev/tags/processes/Recent content in Processes on Ou David | Systems EngineerHugo -- gohugo.ioen-usMon, 15 Jun 2026 13:31:48 +0700https://vvivid.dev/posts/process_api_behind_every_shell_command/Mon, 15 Jun 2026 13:31:48 +0700https://vvivid.dev/posts/process_api_behind_every_shell_command/<p>I&rsquo;ve been reading <a href="https://pages.cs.wisc.edu/~remzi/OSTEP/">Operating Systems: Three Easy Pieces</a>, and today I went through chapter 05, the interlude on the Process API. It is a short chapter, but it clarified something important about how processes actually work.</p> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-sh" data-lang="sh"><span class="line"><span class="cl">grep <span class="s2">&#34;error&#34;</span> app.log <span class="p">|</span> wc -l </span></span></code></pre></div><p>This is a simple shell command. One program reads a file, another program counts the matching lines, and the shell connects them together. Underneath that simple line is one of the most important UNIX ideas: process creation, process replacement, and process coordination.</p>