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Name

acl, facl - get or set a file’s Access Control List (ACL)

Synopsis

#include <sys/acl.h>

int acl(char *pathp, int cmd, int nentries, aclent_t *aclbufp)

int facl(int fildes, int cmd, int nentries, aclent_t *aclbufp)

Description

acl() and facl() get or set the ACL of a file whose name is given by pathp or referenced by the open file descriptor fildes. nentries specifies how many ACL entries fit into buffer aclbufp. acl() is used to manipulate ACL on file system objects.

The following three values for cmd are available.

SETACL
nentries ACL entries, specified in buffer aclbufp, are stored in the file’s ACL . This command can only be executed by a process that has an effective user ID equal to the owner of the file. All directories in the path name must be searchable.
GETACL
Buffer aclbufp is filled with the file’s ACL entries. Read access to the file is not required, but all directories in the path name must be searchable.
GETACLCNT
The number of entries in the file’s ACL is returned. Read access to the file is not required, but all directories in the path name must be searchable.

Return Values

Upon successful completion, if cmd is SETACL , a value of 0 is returned. If cmd is GETACL or GETACLCNT , the number of ACL entries is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error.

Errors

acl() will fail if one or more of the following is true:
EACCESS
The caller does not have access to a component of the pathname.
EINVAL
cmd is not GETACL , SETACL , or GETACLCNT .
EINVAL
cmd is SETACL and nentries is less than three.
EINVAL
cmd is SETACL and the ACL specified in aclbufp is not valid.
EIO
A disk I/O error has occurred while storing or retrieving the ACL .
EPERM
cmd is SETACL and the effective user ID of the caller does not match the owner of the file.
ENOENT
A component of the path does not exist.
ENOSPC
cmd is GETACL and nentries is less than the number of entries in the file’s ACL .
ENOSPC
cmd is SETACL and there is insufficient space in the file system to store the ACL .
ENOTDIR
A component of the path specified by pathp is not a directory.
ENOTDIR
cmd is SETACL and an attempt is made to set a default ACL on a file type other than a directory.
ENOSYS
cmd is SETACL and the file specified by pathp resides on a file system that does not support ACL s. acl() is not supported by this implementation.
EROFS
cmd is SETACL and the file specified by pathp resides on a file system that is mounted read-only.
EFAULT
pathp or aclbufp points to an illegal address.

See Also

getfacl(1) , setfacl(1) , aclcheck(3) , aclsort(3)

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