Can't add applications using sudo apt-get and unofficial ppa: unable to lock directory [duplicate]

Question

My terminal shows this error. I can't add any applications. Please help someone

ashwin@ash:~$ sudo add-apt-repository ppa:tualatrix/ppa
[sudo] password for ashwin: 
 The official Ubuntu Tweak stable repository
 More info: https://launchpad.net/~tualatrix/+archive/ppa

Press [ENTER] to continue or ctrl-c to cancel adding it
gpg: keyring `/tmp/tmpwj1dey/secring.gpg' created
gpg: keyring `/tmp/tmpwj1dey/pubring.gpg' created
gpg: requesting key 0624A220 from hkp server keyserver.ubuntu.com
gpg: /tmp/tmpwj1dey/trustdb.gpg: trustdb created
gpg: key 0624A220: public key "Launchpad PPA for TualatriX" imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1) 
OK

ashwin@ash:~$ sudo apt-get update
E: Could not get lock /var/lib/apt/lists/lock - open (11: Resource temporarily unavailable) 
E: Unable to lock directory /var/lib/apt/lists/

Answer 1

First close all package manager programs such as Synaptic or the Software Center and try the apt-get update again. If that does not solve your problem, have a look at the methods proposed here.