$ sudo apt-get install apache2
E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?

sudo mv /var/lib/dpkg/lock /var/lib/dpkg/lock_backup

sudo apt-get install apache2

sudo rm -vf /var/lib/dpkg/lock_backup