linkat(2)

1LINKAT(2)                  Linux Programmer's Manual                 LINKAT(2)
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NAME

6       linkat - create a file link relative to directory file descriptors
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SYNOPSIS

9       #define _ATFILE_SOURCE
10       #include <unistd.h>
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12       int linkat(int olddirfd, const char *oldpath,
13                  int newdirfd, const char *newpath, int flags);
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DESCRIPTION

16       The  linkat()  system call operates in exactly the same way as link(2),
17       except for the differences described in this manual page.
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19       If the pathname given in oldpath is relative, then  it  is  interpreted
20       relative  to  the directory referred to by the file descriptor olddirfd
21       (rather than relative to the current working directory of  the  calling
22       process, as is done by link(2) for a relative pathname).
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24       If oldpath is relative and olddirfd is the special value AT_FDCWD, then
25       oldpath is interpreted relative to the current working directory of the
26       calling process (like link(2)).
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28       If oldpath is absolute, then olddirfd is ignored.
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30       The interpretation of newpath is as for oldpath, except that a relative
31       pathname is interpreted relative to the directory referred  to  by  the
32       file descriptor newdirfd.
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34       By default, linkat(2), does not dereference oldpath if it is a symbolic
35       link (like link(2)).  Since Linux 2.6.18,  the  flag  AT_SYMLINK_FOLLOW
36       can  be  specified flags to cause oldpath to be dereferenced if it is a
37       symbolic link.  Before kernel 2.6.18, the flags  argument  was  unused,
38       and had to be specified as 0.
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RETURN VALUE

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

45       The same errors that occur for link(2) can  also  occur  for  linkat().
46       The following additional errors can occur for linkat():
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48       EBADF  olddirfd or newdirfd is not a valid file descriptor.
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50       ENOTDIR
51              oldpath  is relative and olddirfd is a file descriptor referring
52              to a file other than a directory; or  similar  for  newpath  and
53              newdirfd
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NOTES

56       See openat(2) for an explanation of the need for linkat().
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CONFORMING TO

59       This  system  call  is  non-standard but is proposed for inclusion in a
60       future revision of POSIX.1.
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VERSIONS

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