waiting for cache lock : could not get lock /var/lib/dpkg/lock-frontend code example

Example 1: E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), is another process using it?

sudo lsof /var/lib/dpkg/lock
sudo lsof /var/lib/apt/lists/lock
sudo lsof /var/cache/apt/archives/lock

Example 2: E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), are you root?

ps aux | grep -i apt