VMS Help CC, Run-time functions, execl  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Passes the name of an image to be activated on a child process.
  This function is nonreentrant.

  Syntax:

       #include <unistd.h>

       int execl (const char *file-spec, const char *arg0,..., (char
       *)0; (POSIX-1)

       int execl (char *file-spec,...); (Compatibility)

  where the ...  is a sequence of pointers to strings.  At least one
  pointer must exist to terminate the list.  This pointer must be the
  null pointer.