Index: head/usr.bin/tty/tty.c
===================================================================
--- head/usr.bin/tty/tty.c	(revision 304219)
+++ head/usr.bin/tty/tty.c	(revision 304220)
@@ -1,79 +1,80 @@
 /*
  * Copyright (c) 1988, 1993
  *	The Regents of the University of California.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 4. Neither the name of the University nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
 
 #ifndef lint
 static const char copyright[] =
 "@(#) Copyright (c) 1988, 1993\n\
 	The Regents of the University of California.  All rights reserved.\n";
 #endif /* not lint */
 
 #ifndef lint
 #if 0
 static char sccsid[] = "@(#)tty.c	8.1 (Berkeley) 6/6/93";
 #endif
 #endif /* not lint */
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 
 static void usage(void);
 
 int
 main(int argc, char *argv[])
 {
 	int ch, sflag;
 	char *t;
 
 	sflag = 0;
 	while ((ch = getopt(argc, argv, "s")) != -1)
 		switch (ch) {
 		case 's':
 			sflag = 1;
 			break;
 		case '?':
 		default:
 			usage();
+			/* NOTREACHED */
 		}
 
-	t = ttyname(0);
+	t = ttyname(STDIN_FILENO);
 	if (!sflag)
 		puts(t ? t : "not a tty");
-	exit(t ? 0 : 1);
+	exit(t ? EXIT_SUCCESS : EXIT_FAILURE);
 }
 
 static void
 usage(void)
 {
-	fprintf(stderr, "usage: tty [-s]\n");
+	fprintf(stderr, "usage: %s [-s]\n", getprogname());
 	exit(2);
 }