1.\" $NetBSD: ttyname.3,v 1.3 1995/02/27 05:54:52 cgd Exp $ 2.\" 3.\" Copyright (c) 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)ttyname.3 8.1 (Berkeley) 6/4/93 35.\" 36.Dd June 4, 1993 37.Dt TTYNAME 3 38.Os 39.Sh NAME 40.Nm ttyname , 41.Nm isatty , 42.Nm ttyslot 43.Nd get name of associated terminal (tty) from file descriptor 44.Sh SYNOPSIS 45.Fd #include <unistd.h> 46.Ft char * 47.Fn ttyname "int fd" 48.Ft int 49.Fn isatty "int fd" 50.Ft int 51.Fn ttyslot 52.Sh DESCRIPTION 53These functions operate on the system file descriptors for terminal 54type devices. These descriptors are not related to the standard 55.Tn I/O 56.Dv FILE 57typedef, but refer to the special device files found in 58.Pa /dev 59and named 60.Pa /dev/tty Ns Em xx 61and for which an entry exists 62in the initialization file 63.Pa /etc/ttys. 64(See 65.Xr ttys 5 . ) 66.Pp 67The 68.Fn isatty 69function 70determines if the file descriptor 71.Fa fd 72refers to a valid 73terminal type device. 74.Pp 75The 76.Fn ttyname 77function 78gets the related device name of 79a file descriptor for which 80.Fn isatty 81is true 82.Pp 83The 84.Fn ttyslot 85function 86fetches the current process' control terminal number from the 87.Xr ttys 5 88file entry. 89.Sh RETURN VALUES 90The 91.Fn ttyname 92function 93returns the null terminated name if the device is found and 94.Fn isatty 95is true; otherwise 96a 97.Dv NULL 98pointer is returned. 99.Pp 100The 101.Fn ttyslot 102function 103returns the unit number of the device file if found; otherwise 104the value zero is returned. 105.Sh FILES 106.Bl -tag -width /etc/ttys -compact 107.It Pa /dev/\(** 108.It Pa /etc/ttys 109.El 110.Sh SEE ALSO 111.Xr ioctl 2 , 112.Xr ttys 5 113.Sh HISTORY 114A 115.Fn isatty , 116.Fn ttyname , 117and 118.Fn ttyslot 119function 120appeared in 121.At v7 . 122.Sh BUGS 123The 124.Fn ttyname 125function leaves its result in an internal static object and returns 126a pointer to that object. Subsequent calls to 127.Fn ttyname 128will modify the same object. 129