LINKAT(2) Linux Programmer's Manual LINKAT(2)
linkat - create a file link relative to directory file descriptors
#include <fcntl.h> /* Definition of AT_* constants */
int linkat(int olddirfd, const char *oldpath,
int newdirfd, const char *newpath, int flags);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
Since glibc 2.10:
_XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
Before glibc 2.10:
The linkat() system call operates in exactly the same way as link(2), except for the dif-
ferences described in this manual page.
If the pathname given in oldpath is relative, then it is interpreted relative to the
directory referred to by the file descriptor olddirfd (rather than relative to the current
working directory of the calling process, as is done by link(2) for a relative pathname).
If oldpath is relative and olddirfd is the special value AT_FDCWD, then oldpath is inter-
preted relative to the current working directory of the calling process (like link(2)).
If oldpath is absolute, then olddirfd is ignored.
The interpretation of newpath is as for oldpath, except that a relative pathname is inter-
preted relative to the directory referred to by the file descriptor newdirfd.
The following values can be bitwise ORed in flags:
AT_EMPTY_PATH (since Linux 2.6.39)
If oldpath is an empty string, create a link to the file referenced by olddirfd
(which may have been obtained using the open(2) O_PATH flag). In this case, old-
dirfd can refer to any type of file, not just a directory. The caller must have
the CAP_DAC_READ_SEARCH capability in order to use this flag; this prevents arbi-
trary users from creating hard links using file descriptors received via a UNIX
domain socket (see the discussion of SCM_RIGHTS in unix(7)).
AT_SYMLINK_FOLLOW (since Linux 2.6.18)
By default, linkat(), does not dereference oldpath if it is a symbolic link (like
link(2)). The flag AT_SYMLINK_FOLLOW can be specified in flags to cause oldpath to
be dereferenced if it is a symbolic link.
Before kernel 2.6.18, the flags argument was unused, and had to be specified as 0.
On success, linkat() returns 0. On error, -1 is returned and errno is set to indicate the
The same errors that occur for link(2) can also occur for linkat(). The following addi-
tional errors can occur for linkat():
EBADF olddirfd or newdirfd is not a valid file descriptor.
ENOENT AT_EMPTY_PATH was specified in flags, but the caller did not have the
oldpath is relative and olddirfd is a file descriptor referring to a file other
than a directory; or similar for newpath and newdirfd
linkat() was added to Linux in kernel 2.6.16; library support was added to glibc in ver-
See openat(2) for an explanation of the need for linkat().
link(2), openat(2), path_resolution(7), symlink(7)
This page is part of release 3.55 of the Linux man-pages project. A description of the
project, and information about reporting bugs, can be found at
Linux 2013-07-21 LINKAT(2)