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# apt-get install acl
# mount -o acls / # cat /etc/fstab
... /dev/ada0p2 / ufs rw,acls 1 1 ...
# getfacl /etc/passwd # setfacl -m "user:user1:---" /etc/passwd # setfacl -x "user:user1:" /etc/passwd # setfacl -b /etc/passwd