Trouvé le problème. La page man n'est pas jour.
info donne :
`--no-same-permissions'
When extracting an archive, subtract the user's umask from files
from the permissions specified in the archive. This is the
default behavior for ordinary users; this option has an effect
only for the superuser.
[^] # Re: HOWTO Hard Disk Upgrade
Posté par morgendorffer . En réponse au message mv hdd1/* hdd2/ ?. Évalué à 0.
info donne :
`--no-same-permissions'
When extracting an archive, subtract the user's umask from files
from the permissions specified in the archive. This is the
default behavior for ordinary users; this option has an effect
only for the superuser.