Waiting for cache lock: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 2834 (unattended-upgr) code example

Example: 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 
# 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 
# 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