/sys$common/syshlp/helplib.hlb CC, Run-time functions, ttyname  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Returns a pointer to the null-terminated name of the terminal
  device associated with file descriptor 0, the default input device
  (stdin).

  Syntax:

       #include <unixio.h>

       char *ttyname(void);