Entries tagged with "Guix"https://kristofferbalintona.me/en-ushttps://kristofferbalintona.me/favicon-rss.pnghttps://kristofferbalintona.mehttps://kristofferbalintona.me/posts/202606190034/https://kristofferbalintona.me/posts/202606190034/<p>Today I stumbled upon a recently published (one month ago) blog post by the Guix team: <a href="https://guix.gnu.org/blog/2026/time-travel-without-borders/">Time travel without borders</a>. It was a worthwhile read.</p> <p><code>guix time-machine</code> is used to go back or forward in time (relative to the current Guix profile) and call other Guix subcommands. For instance, to run the <code>yt-dlp</code> binary from the latest Guix commit:</p> <div><figure><figcaption><span></span><span>Terminal window</span></figcaption><pre><code><div><div><span>guix</span><span> </span><span>time-machine</span><span> </span><span>-q</span><span> </span><span>--</span><span> </span><span>shell</span><span> </span><span>yt-dlp</span><span> </span><span>--</span><span> </span><span>yt-dlp</span><span> </span><span>…</span></div></div></code></pre><div><div></div><div></div></div></figure></div> <p>Another example comes from my personal <a href="https://codeberg.org/krisbalintona/guix-config">Guix config</a>: to test if my home environment configuration would build properly if I did a <code>guix pull</code>, I do something like:</p> <div><figure><figcaption><span></span><span>Terminal window</span></figcaption><pre><code><div><div><span>guix</span><span> </span><span>home</span><span> </span><span>reconfigure</span><span> </span><span>-L</span><span> </span><span>src</span><span> </span><span>--expression=</span><span>'</span><span>(@ (krisb config machines MACHINE home) MACHINE-home-environment)</span><span>'</span></div></div></code></pre><div><div></div><div></div></div></figure></div> <p>Both of the above are examples of going “forward” in time (i.e., forward in the Guix repository commit history), but one can just as easily go back to earlier commits.</p> <p><a href="https://guix.gnu.org/blog/2026/time-travel-without-borders/">The article</a> goes over a recently added feature to <code>guix pull</code> and <code>guix time-machine</code>. I believe it comes from this PR:</p> <div><p><a href="https://codeberg.org/guix/guix/pulls/6745">#6745 - Allow `pull` and `time-machine` to download channel files - guix/guix - Codeberg.org</a></p></div> <p>This new feature basically lets one provide a URL or SWHID (Software Hash Identifiers)^{<a href="#fn-1">[1]</a>} to <code>guix pull</code> or <code>guix time-machine</code> directly. (The latter is more secure, since it involves a content hash.)</p> <p>So, instead of having to do something like the following, where one fetches a file via e.g. <code>wget</code> then calls <code>guix time-machine</code>:</p> <div><figure><figcaption><span></span><span>Terminal window</span></figcaption><pre><code><div><div><span>wget</span><span> </span><span>-O</span><span> </span><span>channels.scm</span><span> \</span></div></div><div><div><span> </span><span>https://ci.guix.gnu.org/eval/latest/channels.scm?spec=master</span></div></div><div><div><span>guix</span><span> </span><span>time-machine</span><span> </span><span>-C</span><span> </span><span>channels.scm</span><span> </span><span>--</span><span> </span><span>shell</span><span> </span><span>…</span></div></div></code></pre><div><div></div><div></div></div></figure></div> <p>or the one-line Bash equivalent:</p> <div><figure><figcaption><span></span><span>Terminal window</span></figcaption><pre><code><div><div><span>guix</span><span> </span><span>time-machine</span><span> \</span></div></div><div><div><span>-C </span><span>&lt;(</span><span>wget</span><span> -O https://ci.guix.gnu.org/eval/latest/channels.scm?spec=master</span><span>)</span><span> \</span></div></div><div><div><span>-- </span><span>shell</span><span> </span><span>…</span></div></div></code></pre><div><div></div><div></div></div></figure></div> <p>We can do the following instead, using a URL directly:</p> <div><figure><figcaption><span></span><span>Terminal window</span></figcaption><pre><code><div><div><span>guix</span><span> </span><span>time-machine</span><span> \</span></div></div><div><div><span>-C </span><span>https://ci.guix.gnu.org/eval/latest/channels.scm?spec=master</span><span> \</span></div></div><div><div><span>-- </span><span>…</span></div></div></code></pre><div><div></div><div></div></div></figure></div> <p>or with a SWHID</p> <div><figure><figcaption><span></span><span>Terminal window</span></figcaption><pre><code><div><div><span>guix</span><span> </span><span>time-machine</span><span> \</span></div></div><div><div><span>-C </span><span>swh:1:cnt:003e1e0c1b9b358082201332c926ae54e9549002</span><span> \</span></div></div><div><div><span>-- </span><span>…</span></div></div></code></pre><div><div></div><div></div></div></figure></div> <p>Really cool!</p> <footer> <h2><p>Footnotes</p></h2> <ol> <li> <a href="#fnref-1">[1]</a> <div> <p>You can learn more about SWHIDs <a href="https://www.swhid.org/">here</a>. They are basically unique IDs for software artifacts. This includes repositories, commits, source code/files, and more. The benefit of SWHIDs here is that it ensures that the content of a URL is not changed under your feet—SWHIDs have a security benefit.</p><p>I learned about these only until recently by another Guix resource, but as of April 23, 2025 SWHIDs are <em>an ISO International Standard</em>!</p> <a href="#fnref-1">↩</a> </div> </li> </ol> </footer>Fri, 19 Jun 2026 00:34:00 GMTGuixTips and Tricks