Editer le fichier /etc/vim/vimrc et ajouter

if has("multi_byte")
        set encoding=utf-8
        setglobal fileencoding=utf-8
        set bomb
        set termencoding=iso-8859-15
        set fileencodings=ucs-bom,iso-8859-15,iso-8859-3,utf-8
else
        echoerr "Sorry, this version of (g)vim was not compiled with +multi_byte"
endif