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

  Returns a pointer to a character string containing the name of the
  user initiating the current process.  This function is
  nonreentrant.

  Syntax:

       #include <unistd.h>

       char *cuserid(char *str);