Re: [Trisquel-users] Trisquel 7 operating system and Windows based viruses

[onpon4]

All package manager frontends, including Add/Remove Applications, show  
whether or not any given program is installed. Even if you use the  
command-line to request the installation of a program you already have  
installed, it will see that it's already installed and tell you that. So no  
worries. :)