It&#x27;s for the same reason that java has to be invoked as<p><pre><code>   &#x2F;usr&#x2F;bin&#x2F;env $JAVA_HOME&#x2F;bin&#x2F;java
</code></pre>
thus raising questions such as <a href="http:&#x2F;&#x2F;unix.stackexchange.com&#x2F;questions&#x2F;229523&#x2F;" rel="nofollow">http:&#x2F;&#x2F;unix.stackexchange.com&#x2F;questions&#x2F;229523&#x2F;</a> .<p>systemd does not permit variable expansions or unit parameters in the first word of ExecStart.