exit with non-zero status if unable to open sysout or... (#496)

src/xrdopt.c

@@ -133,7 +133,7 @@ void print_Xusage(const char *prog)
  -nh-loglevel level        Loglevel for Dodo networking (0..2, optional, default: 0)\n\n");
 #endif
   fprintf(stderr, "Please refer to the manual for further information.\n\n");
-  exit(0);
+  exit(EXIT_FAILURE);
 } /* end print_Xusage() */
 
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