Waiting for cache lock: Could not get lock /var/lib/dpkg/lock-frontend. It is h code example

Example 1: Could not get lock /var/lib/dpkg/lock-frontend - open (11: Resource temporarily unavailable)

Method 1
ps aux | grep -i apt
sudo kill -9 

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 

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

Example 2: 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

Example 3: E: Could not get lock /var/lib/dpkg/lock-frontend - open (11: Resource temporarily unavailable)

sudo rm /var/lib/apt/lists/locksudo rm /var/lib/apt/lists/lock-frontend

Example 4: why upgrade ubuntu then frequently shows this message "It iwating for cache lock: Could not get lock /var/lib/dpkg/lock.frontend.

It iwating for cache lock: Could not get lock /var/lib/dpkg/lock.frontend.