---
name: "acl_set_qualifier"
section: "3"
platform: "linux"
package: "acl"
version: "2.4.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "freebsd", "macos"]
url: "https://new.carta.tech/acl_set_qualifier"
---

# acl\_set\_qualifier(3)

set the qualifier of an ACL entry

## NAME

**acl\_set\_qualifier** – set the qualifier of an ACL entry

## LIBRARY

Linux Access Control Lists library (libacl, -lacl).

## SYNOPSIS

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

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

*int*\

**acl\_set\_qualifier**(*acl\_entry\_t entry\_d*, *const void \*qualifier\_p*);

## DESCRIPTION

The **acl\_set\_qualifier**() function sets the qualifier of the ACL entry indicated by the argument *entry\_d* to the value referred to by the argument *qualifier\_p*. If the value of the tag type in the ACL entry referred to by *entry\_d* is ACL\_USER, then the value referred to by *qualifier\_p* shall be of type *uid\_t*. If the value of the tag type in the ACL entry referred to by *entry\_d* is ACL\_GROUP, then the value referred to by *qualifier\_p* shall be of type *gid\_t*. If the value of the tag type in the ACL entry referred to by *entry\_d* is a tag type for which a qualifier is not supported,  **acl\_set\_qualifier**() returns an error.

Any ACL entry descriptors that refer to the entry referred to by *entry\_d* continue to refer to that entry. This function may cause memory to be allocated. The caller should free any releasable memory, when the ACL is no longer required, by calling **acl\_free**() with a pointer to the ACL as argument.

## RETURN VALUE

The **acl\_set\_qualifier()** function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

## ERRORS

If any of the following conditions occur, the **acl\_set\_qualifier**() function returns -1 and sets *errno* to the corresponding value:

- \[EINVAL\]

  The argument *entry\_d* is not a valid descriptor for an ACL entry.

  The value of the tag type in the ACL entry referenced by the argument *entry\_d* is neither ACL\_USER nor ACL\_GROUP.

  The value pointed to by the argument *qualifier\_p* is not valid.

- \[ENOMEM\]

  The **acl\_set\_qualifier**() function is unable to allocate the memory required for the ACL qualifier.

## STANDARDS

IEEE Std 1003.1e draft 17 (“POSIX.1e”, abandoned)

## SEE ALSO

[acl\_create\_entry(3)](/acl_create_entry/3.md), [acl\_free(3)](/acl_free/3.md), [acl\_get\_permset(3)](/acl_get_permset/3.md), [acl\_get\_qualifier(3)](/acl_get_qualifier/3.md), [acl\_get\_tag\_type(3)](/acl_get_tag_type/3.md), acl\_set\_entry(3), [acl\_set\_permset(3)](/acl_set_permset/3.md), [acl\_set\_tag\_type(3)](/acl_set_tag_type/3.md), [acl(5)](/acl/5.md)

## AUTHOR

Derived from the FreeBSD manual pages written by Robert N M Watson ⟨rwatson@FreeBSD.org⟩, and adapted for Linux by Andreas Gruenbacher ⟨andreas.gruenbacher@gmail.com⟩.