Preparing to replace coreutils 8.5-1ubuntu6 (using .../coreutils_8.5-1ubuntu6_amd64.deb) ...
Unpacking replacement coreutils ...
dpkg: error processing /var/cache/apt/archives/coreutils_8.5-1ubuntu6_amd64.deb (--unpack):
 unable to make backup link of `./usr/bin/md5sum' before installing new version: Operation not permitted
dpkg-deb: error: subprocess paste was killed by signal (Broken pipe)
Processing triggers for install-info ...
/usr/sbin/update-info-dir: ligne 59: /usr/bin/find: No such file
Processing triggers for man-db ...
Errors were encountered while processing:
 /var/cache/apt/archives/coreutils_8.5-1ubuntu6_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)