Get rid of the default Ubuntu repository installed version of Redis.

Just run this sudo aptitude purge command to get rid of any Redis stuff installed via the default Ubuntu repository:

sudo aptitude purge redis-server

Adding the Chris Lea PPA to the system.

First install python-software-properties like this:

sudo aptitude install python-software-properties

Next add the Chris Lea PPA repository to the system like this:

sudo add-apt-repository ppa:chris-lea/redis-server

With that done, run aptitude update to get the new repository picked up like this:

sudo aptitude update

Then install Redis via aptitude like this:

sudo aptitude install redis-server

Check the version number like this:

redis-server --version

And the output should be something like this:

Redis server v=3.0.4 sha=00000000:0 malloc=jemalloc-3.6.0 bits=64 build=e10d4bb04434c274