---
name: "acl_dup"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd", "macos"]
url: "https://new.carta.tech/acl_dup"
---

# acl\_dup(3)

duplicate an ACL

## NAME

**acl\_dup** – duplicate an ACL

## LIBRARY

Standard C Library (libc, -lc)

## SYNOPSIS

**#include \<sys/types.h\>**

**#include \<sys/acl.h\>**

*acl\_t*\

**acl\_dup**(*acl\_t acl*);

## DESCRIPTION

The **acl\_dup**() function returns a pointer to a copy of the ACL pointed to by the argument *acl*.

This function may cause memory to be allocated. The caller should free any releasable memory, when the new ACL is no longer required, by calling [acl\_free(3)](/acl_free/3.md) with the *(void\*)acl\_t* as an argument.

Any existing ACL pointers that refer to the ACL referred to by *acl* shall continue to refer to the ACL.

## IMPLEMENTATION NOTES

FreeBSD's support for POSIX.1e interfaces and features is still under development at this time.

## RETURN VALUES

Upon successful completion, this function shall return a pointer to the duplicate ACL. Otherwise, a value of *(acl\_t)NULL* shall be returned, and *errno* shall be set to indicate the error.

## ERRORS

If any of the following conditions occur, the **acl\_init**() function shall return a value of *(acl\_t)NULL* and set *errno* to the corresponding value:

- \[EINVAL\]

  Argument *acl* does not point to a valid ACL.

- \[ENOMEM\]

  The *acl\_t* to be returned requires more memory than is allowed by the hardware or system-imposed memory management constraints.

## SEE ALSO

[acl(3)](/acl/3.md), [acl\_free(3)](/acl_free/3.md), [acl\_get(3)](/acl_get/3.md), [posix1e(3)](/posix1e/3.md)

## STANDARDS

POSIX.1e is described in IEEE POSIX.1e draft 17. Discussion of the draft continues on the cross-platform POSIX.1e implementation mailing list. To join this list, see the FreeBSD POSIX.1e implementation page for more information.

## HISTORY

POSIX.1e support was introduced in FreeBSD 4.0, and development continues.

## AUTHORS

Robert N M Watson