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.


       EXDEV  oldpath and newpath are not on the same filesystem.

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

       EFAULT oldpath or newpath points outside  your  accessible
              address space.

       EACCES Write access to the directory containing newpath is
              not allowed for the process's effective uid, or one
              of  the  directories  in oldpath or newpath did not
              allow search (execute) permission.

              oldpath or newpath was too long.

       ENOENT A directory component in oldpath  or  newpath  does
              not exist or is a dangling symbolic link.

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

       ENOMEM Insufficient kernel memory was available.

       EROFS  The file is on a read-only filesystem.

       EEXIST newpath already exists.

       ELOOP  Too many symbolic links were encountered in resolv­
              ing oldpath or newpath.

       ENOSPC The device containing the file has no room for  the
              new directory entry.

       EPERM  oldpath is a directory.

       EIO    An I/O error occurred.


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


       SVr4, SVID, POSIX, BSD 4.3, X/OPEN.  SVr4 documents  addi­
       tional  ENOLINK  and  EMULTIHOP  error conditions; POSIX.1
       does not document ELOOP.  X/OPEN does not document EFAULT,
       ENOMEM or EIO.


       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


       symlink(2), unlink(2), rename(2), open(2), stat(2), ln(1)