Find the pathname of a terminal.

    Format

      #include  <unixio.h> (Compatibility)

      char *ttyname  (void); (Compatibility)

      #include  <unistd.h> (OpenVMS V7.3-2 and higher)

      char *ttyname  (int filedes); (OpenVMS V7.3-2 and higher)

      int ttyname_r  (int filedes, char name, size_t

                     namesize); (OpenVMS V7.3-2 and higher),

                     (Integrity servers, Alpha)