diff --git a/src/tty.c b/src/tty.c
new file mode 100644
index 0000000..abd5058
--- /dev/null
+++ b/src/tty.c
@@ -0,0 +1,41 @@
+/* tty.c */
+
+
+
+#include <unistd.h>
+#include <stdio.h>
+
+
+/* tty */
+int tty(void)
+{
+	if(isatty(0) == 1)
+	{
+		char* tty;
+
+		if((tty = ttyname(0)) == NULL)
+			return 2;
+		printf("%s\n", ttyname(0));
+		return 0;
+	}
+	printf("not a tty\n");
+	return 1;
+}
+
+
+/* usage */
+int usage(void)
+{
+	fprintf(stderr, "%s", "Usage: tty\n");
+	return 1;
+}
+
+
+/* main */
+int main(int argc, char * argv[])
+{
+	/* parse command line arguments */
+	if(argc != 1)
+		return usage();
+	return tty();
+}