I am new to ubuntu, I have installed ubuntu on USB and booting from it, I wanted to test my graphics card so want to run glxgears tool .. When I type the command as below to install the package it gives the messages below. The ubuntu is running from usb, please advise why this is not installing.
ubuntu@ubuntu:~$ sudo apt-get install mesa-utils Reading package lists... Done Building dependency tree Reading state information... Done Package mesa-utils is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source 
