1.\" $NetBSD: ttyname.3,v 1.12 2002/10/01 16:48:35 wiz 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 LIBRARY 45.Lb libc 46.Sh SYNOPSIS 47.Fd #include \*[Lt]unistd.h\*[Gt] 48.Ft char * 49.Fn ttyname "int fd" 50.Ft int 51.Fn isatty "int fd" 52.Fd #include \*[Lt]stdlib.h\*[Gt] 53.Ft int 54.Fn ttyslot 55.Sh DESCRIPTION 56These functions operate on the system file descriptors for terminal 57type devices. 58These descriptors are not related to the standard 59.Tn I/O 60.Dv FILE 61typedef, but refer to the special device files found in 62.Pa /dev 63and named 64.Pa /dev/tty Ns Em xx 65and for which an entry exists 66in the initialization file 67.Pa /etc/ttys . 68(See 69.Xr ttys 5 . ) 70.Pp 71The 72.Fn isatty 73function 74determines if the file descriptor 75.Fa fd 76refers to a valid 77terminal type device. 78.Pp 79The 80.Fn ttyname 81function 82gets the related device name of 83a file descriptor for which 84.Fn isatty 85is true. 86.Pp 87The 88.Fn ttyslot 89function 90fetches the current process' control terminal number from the 91.Xr ttys 5 92file entry. 93.Sh RETURN VALUES 94The 95.Fn ttyname 96function 97returns the null terminated name if the device is found and 98.Fn isatty 99is true; otherwise 100a 101.Dv NULL 102pointer is returned and 103.Va errno 104is set to indicate the error. 105.Pp 106The 107.Fn isatty 108function returns 1 if 109.Fa fd 110is associated with a terminal device; otherwise it returns 0 and 111.Va errno 112is set to indicate the error. 113.Pp 114The 115.Fn ttyslot 116function 117returns the unit number of the device file if found; otherwise 118the value zero is returned. 119.Sh FILES 120.Bl -tag -width /etc/ttys -compact 121.It Pa /dev/\(** 122.It Pa /etc/ttys 123.El 124.Sh ERRORS 125The 126.Fn ttyname 127and 128.Fn isatty 129functions will fail if: 130.Bl -tag -width Er 131.It Bq Er EBADF 132The 133.Fa fd 134argument is not a valid file descriptor. 135.It Bq Er ENOTTY 136The 137.Fa fd 138argument does not refer to a terminal device. 139.El 140.Sh SEE ALSO 141.Xr ioctl 2 , 142.Xr ttys 5 143.Sh STANDARDS 144The 145.Fn ttyname 146and 147.Fn isatty 148functions conform to 149.St -p1003.1-90 . 150.Sh HISTORY 151A 152.Fn isatty , 153.Fn ttyname , 154and 155.Fn ttyslot 156function 157appeared in 158.At v7 . 159.Sh BUGS 160The 161.Fn ttyname 162function leaves its result in an internal static object and returns 163a pointer to that object. 164Subsequent calls to 165.Fn ttyname 166will modify the same object. 167