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

NAME
       link - make a new name for a file
SYNOPSIS
       #include <unistd.h>
       int link(const char *oldpath, const char *newpath);
DESCRIPTION
       link()  creates  a  new link (also known as a hard link) to an existing
       file.
       If newpath exists it will not be overwritten.
       This new name may be used exactly as the old  one  for  any  operation;
       both names refer to the same file (and so have the same permissions and
       ownership) and it is impossible to tell which name was the "original".
RETURN VALUE
       On success, zero is returned.  On error, -1 is returned, and  errno  is
       set appropriately.
ERRORS
       EACCES Write  access  to the directory containing newpath is denied, or
              search permission is denied for one of the  directories  in  the
              path  prefix  of  oldpath  or  newpath.   (See also path_resolu-
              tion(7).)
       EDQUOT The user's quota of disk blocks on  the  file  system  has  been
              exhausted.
       EEXIST newpath already exists.
       EFAULT oldpath or newpath points outside your accessible address space.
       EIO    An I/O error occurred.
       ELOOP  Too many symbolic links were encountered in resolving oldpath or
              newpath.
       EMLINK The file referred to by oldpath already has the  maximum  number
              of links to it.
       ENAMETOOLONG
              oldpath or newpath was too long.
       ENOENT A directory component in oldpath or newpath does not exist or is
              a dangling symbolic link.
       ENOMEM Insufficient kernel memory was available.
       ENOSPC The device containing the file has no room for the new directory
              entry.
       ENOTDIR
              A component used as a directory in oldpath or newpath is not, in
              fact, a directory.
       EPERM  oldpath is a directory.
       EPERM  The file system containing oldpath and newpath does not  support
              the creation of hard links.
       EPERM (since Linux 3.6)
              The  caller  does  not  have permission to create a hard link to
              this   file   (see   the   description   of    /proc/sys/fs/pro-
              tected_hardlink in proc(5)).
       EROFS  The file is on a read-only file system.
       EXDEV  oldpath  and  newpath  are  not on the same mounted file system.
              (Linux permits a file system to be mounted at  multiple  points,
              but  link() does not work across different mount points, even if
              the same file system is mounted on both.)
CONFORMING TO
       SVr4, 4.3BSD, POSIX.1-2001 (but see NOTES).
NOTES
       Hard links, as created by link(), cannot span file systems.   Use  sym-
       link(2) if this is required.
       POSIX.1-2001  says  that  link()  should dereference oldpath if it is a
       symbolic link.  However, since kernel 2.0, Linux does  not  do  so:  if
       oldpath is a symbolic link, then newpath is created as a (hard) link to
       the same symbolic link file (i.e., newpath becomes a symbolic  link  to
       the  same  file  that  oldpath  refers to).  Some other implementations
       behave in the same manner as Linux.  POSIX.1-2008 changes the  specifi-
       cation  of  link(),  making  it implementation-dependent whether or not
       oldpath is dereferenced if it is a symbolic link.  For precise  control
       over  the  treatment  of  symbolic  links  when  creating  a  link, see
       linkat(2).
BUGS
       On NFS file systems, the return code may  be  wrong  in  case  the  NFS
       server  performs  the link creation and dies before it can say so.  Use
       stat(2) to find out if the link got created.
SEE ALSO
       ln(1), linkat(2), open(2), rename(2), stat(2),  symlink(2),  unlink(2),
       path_resolution(7), symlink(7)
COLOPHON
       This  page  is  part of release 3.53 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                             2013-01-27                           LINK(2)