How Do I Update Linux Software On Ubuntu From Command Line?

Use this:

sudo apt update        <span class="hljs-comment"># Fetches the list of available updates</span>
sudo apt upgrade       <span class="hljs-comment"># Installs some updates; does not remove packages</span>
sudo apt full-upgrade  <span class="hljs-comment"># Installs updates; may also remove some packages, if needed</span>
sudo apt autoremove    <span class="hljs-comment"># Removes any old packages that are no longer needed</span>

Documentation about each apt option can be found in the the manpages for apt. These are also available by running man apt in your terminal.

Use of both upgrade and full-upgrade together is usually not needed, but it may help in some cases: see Debian documentation about Upgrades from Debian 9.