How to check wheter POSIX ACL is enabled for a given path

Question

After reading the man page of getfacl / setfacl I could not find an obvious/robust/elegant method to check whether acl is enabled for a given path in (ba)sh.

Any suggestions?

Answer 1

{
  # Determine what the mount point for the path is:
  MOUNT_POINT=$(df -P $FILENAME | tail -n 1 | awk '{print $6}')
  # Get the mount options for the path:
  MOUNT_OPTS=$(awk '$2=="'$MOUNT_POINT'" { print $4 }' /proc/mounts)
  # Check to see if acl is one of the mount points:
  echo $MOUNT_OPTS | tr , \\\n | grep '^acl$' -q
  if [ $? -eq 0 ]; then
    echo "ACLs enabled"
  else
    echo "ACLs disabled"
  fi
}