Thanks for answer, I did it but there is an extra line ( the first 900 http://ftp.fr.debian.org/debian/ squeeze/main Translation-fr ) how to remove it:
*here is my file* cat /etc/apt/preferences Package: * Pin: origin "" Pin-Priority: 900 Package: * Pin: origin "localhost" Pin-Priority: 600 Package: * Pin: origin "ftp.fr.debian.org" Pin-Priority: 500 Here is the output 100 /var/lib/dpkg/status release a=now 900 http://ftp.fr.debian.org/debian/ squeeze/main Translation-fr 500 http://ftp.fr.debian.org/debian/ squeeze/non-free i386 Packages release v=6.0.1,o=Debian,a=stable,n=squeeze,l=Debian,c=non-free origin ftp.fr.debian.org 500 http://ftp.fr.debian.org/debian/ squeeze/contrib i386 Packages release v=6.0.1,o=Debian,a=stable,n=squeeze,l=Debian,c=contrib origin ftp.fr.debian.org 500 http://ftp.fr.debian.org/debian/ squeeze/main i386 Packages release v=6.0.1,o=Debian,a=stable,n=squeeze,l=Debian,c=main origin ftp.fr.debian.org 600 ftp://localhost/extra6Bis/ Packages origin localhost 900 file:/opt/extra6/ Packages thanks a lot