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       link - make a new name for a file


       #include <unistd.h>

       int link(const char *oldpath, const char *newpath);


       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".


       On success, zero is returned.  On error, -1 is returned, and errno is set appropriately.


       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 filesystem 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.

              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.

              A component used as a directory in oldpath or newpath is not, in fact, a directory.

       EPERM  oldpath is a directory.

       EPERM  The filesystem containing oldpath and newpath does not support the creation of hard

       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 filesystem.

       EXDEV  oldpath and newpath are not on the  same  mounted  filesystem.   (Linux  permits  a
              filesystem  to  be  mounted  at  multiple  points,  but link() does not work across
              different mount points, even if the same filesystem is mounted on both.)


       SVr4, 4.3BSD, POSIX.1-2001 (but see NOTES).


       Hard links, as created by link(), cannot span filesystems.   Use  symlink(2)  if  this  is

       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 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).


       On NFS filesystems, 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.


       ln(1),  linkat(2), open(2), rename(2), stat(2), symlink(2), unlink(2), path_resolution(7),


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