Answers for "could not get lock var/lib/dpkg/lock-frontend"

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

ps aux | grep -i dpkg

// Kill processes which are running
sudo kill -9 <pid>

// Restart the accounts daemon
sudo systemctl restart accounts-daemon

E: Could not get lock /var/lib/dpkg/lock-frontend - open (11: Resource temporarily unavailable) E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), is another process using it?

ps aux | grep -i apt

sudo kill <process_id>
# Check if the process was killed by running the ‘ps aux | grep -i apt’ command. If it is still running, force kill it with SIGKILL signal:

sudo kill -9 <process_id>
# Another, easier way would be to use the killall command. This will kill all the instances of a running program:

sudo killall apt apt-get

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

sudo kill -9 PID
sudo rm /var/lib/dpkg/lock-frontend
sudo apt update

waiting for cache lock, Could not get lock /var/lib/dpkg/lock-frontend.

sudo lsof /var/lib/dpkg/lock
or 
sudo lsof /var/lib/apt/lists/lock
or
sudo lsof /var/lib/dpkg/lock-frontend

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

For godaddy users. Please check if your firewall is not blocking port number
2224 which can essentially lead to file permission issue even you are logged in
as the root user.

https://in.godaddy.com/help/unblock-ports-required-for-my-gen-4-server-27924