sisyphus@sisyphus5-desktop:~$ sudo apt-get install pentium-builder Reading package lists... Done Building dependency tree Reading state information... Done Package pentium-builder 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 E: Package 'pentium-builder' has no installation candidate sisyphus@sisyphus5-desktop:~$