READLINKAT(2) Linux Programmer's Manual READLINKAT(2)
readlinkat - read value of a symbolic link relative to a directory file descriptor
#include <fcntl.h> /* Definition of AT_* constants */
int readlinkat(int dirfd, const char *pathname,
char *buf, size_t bufsiz);
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 readlinkat() system call operates in exactly the same way as readlink(2), except for
the differences described in this manual page.
If the pathname given in pathname is relative, then it is interpreted relative to the
directory referred to by the file descriptor dirfd (rather than relative to the current
working directory of the calling process, as is done by readlink(2) for a relative path-
If pathname is relative and dirfd is the special value AT_FDCWD, then pathname is inter-
preted relative to the current working directory of the calling process (like read-
If pathname is absolute, then dirfd is ignored.
Since Linux 2.6.39, pathname can be an empty string, in which case the call operates on
the file referred to by dirfd (which may have been obtained using the open(2) O_PATH
flag). In this case, dirfd can refer to any type of file, not just a directory.
On success, readlinkat() returns the number of bytes placed in buf. On error, -1 is
returned and errno is set to indicate the error.
The same errors that occur for readlink(2) can also occur for readlinkat(). The following
additional errors can occur for readlinkat():
EBADF dirfd is not a valid file descriptor.
pathname is relative and dirfd is a file descriptor referring to a file other than
readlinkat() was added to Linux in kernel 2.6.16; library support was added to glibc in
See openat(2) for an explanation of the need for readlinkat().
openat(2), readlink(2), path_resolution(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 2013-07-31 READLINKAT(2)