Comment exécuter resolvconf sans avertissement ?

Tout d'abord, c'est un AVERTISSEMENT .
Voici l'approche pour votre question de la page de manuel resolvconf :

Normally  the  resolvconf  program is run only by network interface configuration programs
such as ifup(8),  ifdown,  NetworkManager(8),  dhclient(8),  and  pppd(8);  and  by  local
nameservers  such  as  dnsmasq(8).  These programs obtain nameserver information from some
source and push it to resolvconf.
...
To  make  the  resolver  use  this  dynamically  generated resolver configuration file the
administrator   should   ensure   that   /etc/resolv.conf   is   a   symbolic   link    to
/run/resolvconf/resolv.conf.   This  link  is  normally  created  on  installation  of the
resolvconf package.  The link is never modified by the resolvconf program itself.  If  you
find  that  /etc/resolv.conf is not being updated, please check to make sure that the link
is intact.

Ce que vous devez faire pour vous débarrasser du WARNING est de recréer le lien symbolik. Vous avez deux options :

1. Soit vous recréez le lien symbolique selon la page de manuel avec

   rm -f /etc/resolv.conf # Delete actual file/symlink 
   ln -s /run/resolvconf/resolv.conf /etc/resolv.conf # recreate the symlink

   Vous devez pointer vers le bon fichier : /run/resolvconf/resolv.conf et non à /var/run/NetworkManager/resolv.conf .

2. Dites à resolvconf de ne pas vous montrer WARNING en utilisant REPORT_ABSENT_SYMLINK l'option REPORT_ABSENT_SYMLINK :

   echo 'REPORT_ABSENT_SYMLINK="no"' >> /etc/default/resolvconf