<p>I am following <a href="https://www.youtube.com/watch?v=ThEsWl3sYtM" rel="nofollow noreferrer">this</a> youtube tutorial and the instructor runs this command.</p>

<pre class="lang-sh prettyprint-override"><code>helm install --name istio incubator/istio --namespace istio-system --devel
helm upgrade istio incubator/istio --reuse-values --set istio.install=true --devel
</code></pre>

<p>What does the <code>--devel</code> flag do? I cant seem to find its reference?</p>

<p>Omitting the <code>--devel</code> flag gives this error</p>

<pre class="lang-sh prettyprint-override"><code>Error: failed to download "incubator/istio" (hint: running `helm repo update` may help)
</code></pre>

<pre><code>helm install --help | grep devel

  --devel                    use development versions, too. Equivalent to version '&gt;0.0.0-0'. If --version is set, this is ignored.
</code></pre>

<p><a href="https://helm.sh/docs/helm/#helm-upgrade" rel="nofollow noreferrer">HELM UPGRADE</a> manual:</p>

<blockquote>
  <p>This command upgrades a release to a specified version of a chart
  and/or updates chart values.</p>
  
  <p>Required arguments are release and chart. The chart argument can be
  one of: - a chart reference(‘stable/mariadb’); use ‘–version’ and
  ‘–devel’ flags for versions other than latest, - a path to a chart
  directory, - a packaged chart, - a fully qualified URL.</p>
</blockquote>
