https://main.gwhlol.pages.dev/ Recent content on gwh.lol Hugo en-US Sun, 01 Mar 2026 00:41:38 -0600 https://main.gwhlol.pages.dev/posts/csplit/ Sun, 01 Mar 2026 00:41:38 -0600 https://main.gwhlol.pages.dev/posts/csplit/ <h1 id="csplit">csplit</h1> <blockquote> <p>csplit - split a file into sections determined by context lines</p> </blockquote> <h2 id="introduction">introduction</h2> <p>Sometimes you have a file of certficiates that you want to split into component files.</p> <p>The source file looks like this:</p> <pre tabindex="0"><code>-----BEGIN CERTIFICATE----- MIIGXzCCBeWgAwIBAgISBrIDKzxu2DUBARSOuwi/l1h/MAoGCCqGSM49BAMDMDIx ... -----END CERTIFICATE----- -----BEGIN CERTIFICATE----- MIIGXzCCBeWgAwIBAgISBrIDKzxu2DUBARSOuwi/l1h/MAoGCCqGSM49BAMDMDIx ... -----END CERTIFICATE----- -----BEGIN CERTIFICATE----- MIIGXzCCBeWgAwIBAgISBrIDKzxu2DUBARSOuwi/l1h/MAoGCCqGSM49BAMDMDIx ... -----END CERTIFICATE----- </code></pre><p>We can split on the first line: <code>-----BEGIN CERTIFICATE-----</code>. Every time we encounter that line, split into a new file.</p>