[enrico] provaccia > tlmgr --dry-run update --all
tlmgr: package repository ctan.mirror.garr.it/mirrors/CTAN/systems/texlive/tlnet
update: dry run, no changes will be made
You don't have permission to change the installation in any way,
specifically, the directory /usr/local/texlive/2014/tlpkg/ is not writable.
Please run this program as administrator, or contact your local admin.
Continuing due to --dry-run
tlmgr: saving backups to /usr/local/texlive/2014/tlpkg/backups
[ 1/29] auto-remove: datetime ... done