How do I unlock “/var/lib/apt/lists/”?

Question

I was installing an item using package manager when it froze. I used Alt+F2 to close it.

Afterwards, whenever I try to install anything via apt-get, the terminal reads

E: Could not get lock /var/lib/apt/lists/lock - open (11: Resource temporarily unavailable)
E: Unable to lock directory /var/lib/apt/lists/

How do I unlock "/var/lib/apt/lists/"?

Answer 1

You can delete the lock file with

sudo rm /var/lib/apt/lists/lock

you may also need to delete the lock file in the cache directory

sudo rm /var/cache/apt/archives/lock

after that try open synaptic again

Answer 2

You will need to use sudo, of course, with apt-get. That's the first thing

If you are using the package manager, and it froze/crashed, you may need to do a specific dpkg command I do not know off the top of my head to resume/repair the incompletely installed packages.