NAME

       readlinkat - read value of a symbolic link relative to a directory file descriptor

SYNOPSIS

       #include <fcntl.h> /* Definition of AT_* constants */
       #include <unistd.h>

       int readlinkat(int dirfd, const char *pathname,
                      char *buf, size_t bufsiz);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       readlinkat():
           Since glibc 2.10:
               _XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:
               _ATFILE_SOURCE

DESCRIPTION

       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
       pathname).

       If  pathname  is  relative  and  dirfd  is  the  special  value AT_FDCWD, then pathname is
       interpreted relative to the  current  working  directory  of  the  calling  process  (like
       readlink(2)).

       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.

RETURN VALUE

       On  success,  readlinkat()  returns  the  number  of bytes placed in buf.  On error, -1 is
       returned and errno is set to indicate the error.

ERRORS

       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.

       ENOTDIR
              pathname  is relative and dirfd is a file descriptor referring to a file other than
              a directory.

VERSIONS

       readlinkat() was added to Linux in kernel 2.6.16; library support was added  to  glibc  in
       version 2.4.

CONFORMING TO

       POSIX.1-2008.

NOTES

       See openat(2) for an explanation of the need for readlinkat().

SEE ALSO

       openat(2), readlink(2), path_resolution(7)

COLOPHON

       This  page  is  part of release 3.54 of the Linux man-pages project.  A description of the
       project,    and    information    about    reporting    bugs,    can    be    found     at
       http://www.kernel.org/doc/man-pages/.