Linux Access Control Lists library (libacl, -lacl).  The function
copies  the contents of the ACL entry indicated by the descriptor
to the existing ACL entry indicated by the  descriptor.  The  and
descriptors  may  refer  to entries in different ACLs.  If any of
the following conditions occur, the function returns and sets  to
the  corresponding value: The argument or is not a valid descrip‐
tor for an ACL entry.  The arguments and reference the  same  ACL
entry.  IEEE Std 1003.1e draft 17 (“POSIX.1e”, abandoned) Derived
from the FreeBSD manual pages written by and adapted for Linux by