add tty

tty.c

@@ -0,0 +1,24 @@
+/* See LICENSE file for copyright and license details. */
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int
+main(void)
+{
+	char *tty;
+
+	if((tty = ttyname(STDIN_FILENO))) {
+		puts(tty);
+		return 0;
+	}
+	else if(errno == ENOTTY) {
+		puts("not a tty");
+		return 1;
+	}
+	else {
+		perror("ttyname");
+		return 2;
+	}
+}