sudo reports an error

 Check that your hostname is well declared in /etc/hosts:

mgirond@pepa:~$ hostname

xxxx

mgirond@pepa:~$ cat /etc/hosts

127.0.0.1 localhost

127.0.0.1 xxxx

# The following lines are desirable for IPv6 capable hosts

::1 ip6-localhost ip6-loopback

fe00::0 ip6-localnet

ff00::0 ip6-mcastprefix

ff02::1 ip6-allnodes

ff02::2 ip6-allrouters

ff02::3 ip6-allhosts