&gt; That&#x27;s the purpose of &#x2F;usr&#x2F;local.<p>I think you must have ignored a substantial portion of my comment. Let&#x27;s take a look at what (part of) my Nix store looks like (you&#x27;ll see it fundamentally looks nothing like &#x2F;usr&#x2F;local):<p><pre><code>  &#x2F;nix&#x2F;store&#x2F;2mmvks92lx37xghj0795ldzrg50lh2pg-bash-4.3-p42
  ├── bin
  │   ├── bash
  │   ├── bashbug
  │   └── sh -&gt; bash
  └── share
      ├── info
      │   ├── bash.info
      …   …
      └── man
          └── man1
              ├── bash.1.gz
              └── bashbug.1.gz
  
  &#x2F;nix&#x2F;store&#x2F;8g6gb6r49fxsrp547rdi3zr06vd69khq-git-2.7.4
  ├── bin
  │   ├── git
  │   ├── git-cvsserver
  │   ├── git-http-backend -&gt; &#x2F;nix&#x2F;store&#x2F;8g6gb6r49fxsrp547rdi3zr06vd69khq-git-2.7.4&#x2F;libexec&#x2F;git-core&#x2F;git-http-backend
  │   ├── git-receive-pack -&gt; git
  │   ├── git-shell
  │   ├── git-upload-archive -&gt; git
  …   └── git-upload-pack
  </code></pre>
Note that each package under &#x2F;nix&#x2F;store is its own prefix; that is, it contains its own bin, lib, share, etc.<p>&#x2F;usr&#x2F;local is a dumping ground &quot;for use by the system administrator when installing software locally&quot;[1]. If you need multiple versions of automake installed: tough luck, the paths collide. If you need multiple versions of Erlang: tough luck, the paths collide.<p>Would you like to be able to rollback your system by changing <i>one</i> symlink[2]? Too bad: when you last installed packages into &#x2F;usr&#x2F;local, your package manager clobbered the previous version.<p>Technically, we could make &#x2F;usr&#x2F;local a symlink forest pointing into &#x2F;nix&#x2F;store, but we don&#x27;t: we want to make sure that only the packages we explicitly declared are picked up by build tools, rather than defaulting to searching through the currently &quot;installed&quot; packages.<p>&gt; &#x2F;nix&#x2F;store? Really? You can&#x27;t just make up new root level directories. That&#x27;s so wrong.<p>Can you substantiate your claim? Note that &quot;it doesn&#x27;t feel right&quot; doesn&#x27;t count as a rational criticism.<p>[1]: <a href="http:&#x2F;&#x2F;www.pathname.com&#x2F;fhs&#x2F;pub&#x2F;fhs-2.3.html#USRLOCALLOCALHIERARCHY" rel="nofollow">http:&#x2F;&#x2F;www.pathname.com&#x2F;fhs&#x2F;pub&#x2F;fhs-2.3.html#USRLOCALLOCALHI...</a><p>[2]: This probably sounds like a bold claim. I tried to explain how this works above, but if you don&#x27;t believe me, feel free to ask and I&#x27;ll explain further. Alternatively, feel free to read the first paragraph here: <a href="http:&#x2F;&#x2F;nixos.org&#x2F;nix&#x2F;manual&#x2F;#sec-profiles" rel="nofollow">http:&#x2F;&#x2F;nixos.org&#x2F;nix&#x2F;manual&#x2F;#sec-profiles</a>