error encountered while creating a virtual environment in Ubuntu [duplicate]

How do I get to the Universe Repository in supported versions of Ubuntu?

If you want in one command and not use Software source ticking then in terminal put:

sudo add-apt-repository universe

On older versions of Ubuntu, you might have to use a full source line:

sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu $(lsb_release -sc) universe"

To enable all Ubuntu software (main universe restricted multiverse) repositories use

sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu $(lsb_release -sc) main universe restricted multiverse"

you can add also partner repository with different link (see difference is ubuntu to canonical)

sudo add-apt-repository "deb http://archive.canonical.com/ubuntu $(lsb_release -sc) partner"

Then update the package list:

sudo apt-get update

p.s.

$(lsb_release -sc) checks your Ubuntu version and puts its name in the source link. Since 12.04 is called precise, you can test in a terminal that lsb_release -sc gives precise. That adds the precise name of your Ubuntu release in Software sources. Wrong word and nothing will work.

For all differences in repositories read https://help.ubuntu.com/community/Repositories/Ubuntu

First, open software center. Click on 'edit' and then 'software sources' to open the software sources window. Once that is open, check the box that says, "Community-maintained free and open-source software (universe)."

Now, all the universe packages should show up in software center just like all the other ones.

More information:

• How do I enable the "Universe" repository from the command line?

Command Line Way of enabling Ubuntu software Repositories For 12.10 and above:

To enable main repository,

sudo add-apt-repository main

To enable universe repository,

sudo add-apt-repository universe

To enable multiverse repository,

sudo add-apt-repository multiverse

To enable restricted repository,

sudo add-apt-repository restricted

NOTE:

After enabling the repositories, don't forget to update it.Run the below command to update the repositories,

sudo apt-get update