ACL_SET_FILE(3) BSD Library Functions Manual ACL_SET_FILE(3)


acl_set_file — set an ACL by filename


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


#include <sys/types.h>
#include <sys/acl.h>


acl_set_file(const char *path_p, acl_type_t type, acl_t acl);


The acl_set_file() function associates an access ACL with a file or directory, or associates a default ACL with a directory. The pathname for the file or directory is pointed to by the argument path_p.

The effective user ID of the process must match the owner of the file or directory or the process must have the CAP_FOWNER capability for the request to succeed.

The value of the argument type is used to indicate whether the access ACL or the default ACL associated with path_p is being set. If the type parameter is ACL_TYPE_ACCESS, the access ACL of path_p shall be set. If the type parameter is ACL_TYPE_DEFAULT, the default ACL of path_p shall be set. If the argument type specifies a type of ACL that cannot be associated with path_p, then the function fails.

The acl parameter must reference a valid ACL according to the rules described on the acl_valid(3) manual page if the type parameter is ACL_TYPE_ACCESS, and must either reference a valid ACL or an ACL with zero ACL entries if the type parameter is ACL_TYPE_DEFAULT. If the acl parameter references an empty ACL, then the acl_set_file() function removes any default ACL associated with the directory referred to by the path_p parameter.


The acl_set_file() function returns the value 0 if successful; otherwise the value −1 is returned and the global variable errno is set to indicate the error.


If any of the following conditions occur, the acl_set_file() function returns -1 and sets errno to the corresponding value:


Search permission is denied for a component of the path prefix or the object exists and the process does not have appropriate access rights.

Argument type specifies a type of ACL that cannot be associated with path_p.


The argument acl does not point to a valid ACL.

The ACL has more entries than the file referred to by path_p can obtain.

The type parameter is not ACL_TYPE_ACCESS or ACL_TYPE_DEFAULT.

The type parameter is ACL_TYPE_DEFAULT, but the file referred to by path_p is not a directory.


The length of the argument path_p is too long.


The named object does not exist or the argument path_p points to an empty string.


The directory or file system that would contain the new ACL cannot be extended or the file system is out of file allocation resources.


A component of the path prefix is not a directory.


The file identified by path_p cannot be associated with the ACL because the file system on which the file is located does not support this.


The process does not have appropriate privilege to perform the operation to set the ACL.


This function requires modification of a file system which is currently read-only.


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

The behavior of acl_set_file() when the acl parameter refers to an empty ACL and the type parameter is ACL_TYPE_DEFAULT is an extension in the Linux implementation, in order that all values returned by acl_get_file() can be passed to acl_set_file(). The POSIX.1e function for removing a default ACL is acl_delete_def_file().


acl_delete_def_file(3), acl_get_file(3), acl_set_fd(3), acl_valid(3), acl(5)


Derived from the FreeBSD manual pages written by Robert N M Watson ⟨⟩ , and adapted for Linux by Andreas Gruenbacher ⟨⟩ .

Linux ACL March 23, 2002 Linux ACL


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