Could not get lock /var/lib/dpkg/lock-frontend - open (11: Resource temporarily unavailable)
Method 1
ps aux | grep -i apt
sudo kill -9 <process_id>
Method 2
sudo lsof /var/lib/dpkg/lock
sudo lsof /var/lib/apt/lists/lock
sudo lsof /var/cache/apt/archives/lock
sudo kill -9 <process_id>
sudo rm /var/lib/apt/lists/lock
sudo rm /var/cache/apt/archives/lock
sudo rm /var/lib/dpkg/lock
sudo dpkg --configure -a
sudo apt update