Upgrade Composer on Ubuntu 20.04
I’m running Ubuntu 20.04 and installed Composer from via apt. This installed the depreciated 1.x version of Composer for which self-update is not recognized. I was able to upgrade to version 2.15 using the following commands.
sudo apt remove composer
sudo apt update
sudo apt install curl
sudo curl -s https://getcomposer.org/installer | php
sudo mv composer.phar /usr/bin/composer