layke@Layke:~$ sudo aptitude install ruby-full
The following NEW packages will be installed:
  libtcltk-ruby1.9.1{ab} ri1.9.1{ab} ruby-full ruby1.9.1-full{ab} 
0 packages upgraded, 4 newly installed, 0 to remove and 4 not upgraded.
Need to get 2,917 kB of archives. After unpacking 18.8 MB will be used.
The following packages have unmet dependencies:
 libtcltk-ruby1.9.1 : Depends: libruby1.9.1 (>= 1.9.2.0) which is a virtual package.
                      Depends: libtcl8.5 (>= 8.5.0) but it is not installable.
                      Depends: libtk8.5 (>= 8.5.0) which is a virtual package.
 ruby1.9.1-full : Depends: ruby1.9.1 (>= 1.9.3.484-2ubuntu1.2) which is a virtual package.
                  Depends: libruby1.9.1-dbg (>= 1.9.3.484-2ubuntu1.2) which is a virtual package.
                  Depends: ruby1.9.1-dev (>= 1.9.3.484-2ubuntu1.2) which is a virtual package.
                  Depends: ruby1.9.1-examples (>= 1.9.3.484-2ubuntu1.2) which is a virtual package.
 ri1.9.1 : Depends: ruby1.9.1 (>= 1.9.3.484-2ubuntu1.2) which is a virtual package.
The following actions will resolve these dependencies:

     Keep the following packages at their current version:                   
1)     libtcltk-ruby1.9.1 [Not Installed]                                    
2)     ri1.9.1 [Not Installed]                                               
3)     ruby-full [Not Installed]                                             
4)     ruby1.9.1-full [Not Installed]                                        

     Leave the following dependencies unresolved:                            
5)     ruby1.9.1-full recommends libtcltk-ruby1.9.1 (>= 1.9.3.484-2ubuntu1.2)