If you have an error Erreur de GPG :  ... NO_PUBKEY when you update your apt list (e.g. with command sudo aptitude update), the solution is in  Ubuntu-FR documentation.

Carry on reading GPG error: NO_PUBKEY →

There's always been argument about the use of aptitude or of  apt-get but there's also  synaptic and software-center (Ubuntu software center): which one to chose ?

Carry on reading Aptitude vs apt-get vs synaptic vs software-center →