linux man page for linkat

LINKAT(2)						     Linux Programmer's Manual							 LINKAT(2)

NAME
       linkat - create a file link relative to directory file descriptors

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

       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)):

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

DESCRIPTION
       The linkat() system call operates in exactly the same way as link(2), except for the differences 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 interpreted 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 interpreted relative to the directory referred to by
       the file descriptor newdirfd.

       By default, linkat(), does not dereference oldpath if it is a symbolic link (like link(2)).  Since Linux 2.6.18, 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.

RETURN VALUE
       On success, linkat() returns 0.	On error, -1 is returned and errno is set to indicate the error.

ERRORS
       The same errors that occur for link(2) can also occur for linkat().  The following additional errors can occur for linkat():

       EBADF  olddirfd or newdirfd is not a valid file descriptor.

       ENOTDIR
	      oldpath is relative and olddirfd is a file descriptor referring to a file other  than  a	directory;  or	similar  for  newpath  and
	      newdirfd

VERSIONS
       linkat() was added to Linux in kernel 2.6.16.

CONFORMING TO
       POSIX.1-2008.

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

SEE ALSO
       link(2), openat(2), path_resolution(7), symlink(7)

COLOPHON
       This  page is part of release 3.27 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/.

Linux								    2009-12-13								 LINKAT(2)