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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_resolution(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 sym-
              bolic 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/protected_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  symlink(2)  if  this  is
       required.

       POSIX.1-2001  says  that link() should dereference oldpath if it is a symbolic link.  How-
       ever, 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 sym-
       bolic link to the same file that oldpath refers to).  Some other implementations behave in
       the  same  manner  as  Linux.  POSIX.1-2008 changes the specification 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)

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