1.\" $NetBSD: ttyname.3,v 1.11 2002/02/07 07:00:18 ross 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. These descriptors are not related to the standard 58.Tn I/O 59.Dv FILE 60typedef, but refer to the special device files found in 61.Pa /dev 62and named 63.Pa /dev/tty Ns Em xx 64and for which an entry exists 65in the initialization file 66.Pa /etc/ttys . 67(See 68.Xr ttys 5 . ) 69.Pp 70The 71.Fn isatty 72function 73determines if the file descriptor 74.Fa fd 75refers to a valid 76terminal type device. 77.Pp 78The 79.Fn ttyname 80function 81gets the related device name of 82a file descriptor for which 83.Fn isatty 84is true. 85.Pp 86The 87.Fn ttyslot 88function 89fetches the current process' control terminal number from the 90.Xr ttys 5 91file entry. 92.Sh RETURN VALUES 93The 94.Fn ttyname 95function 96returns the null terminated name if the device is found and 97.Fn isatty 98is true; otherwise 99a 100.Dv NULL 101pointer is returned and 102.Va errno 103is set to indicate the error. 104.Pp 105The 106.Fn isatty 107function returns 1 if 108.Fa fd 109is associated with a terminal device; otherwise it returns 0 and 110.Va errno 111is set to indicate the error. 112.Pp 113The 114.Fn ttyslot 115function 116returns the unit number of the device file if found; otherwise 117the value zero is returned. 118.Sh FILES 119.Bl -tag -width /etc/ttys -compact 120.It Pa /dev/\(** 121.It Pa /etc/ttys 122.El 123.Sh ERRORS 124The 125.Fn ttyname 126and 127.Fn isatty 128functions will fail if: 129.Bl -tag -width Er 130.It Bq Er EBADF 131The 132.Fa fd 133argument is not a valid file descriptor. 134.It Bq Er ENOTTY 135The 136.Fa fd 137argument does not refer to a terminal device. 138.El 139.Sh SEE ALSO 140.Xr ioctl 2 , 141.Xr ttys 5 142.Sh STANDARDS 143The 144.Fn ttyname 145and 146.Fn isatty 147functions conform to 148.St -p1003.1-90 . 149.Sh HISTORY 150A 151.Fn isatty , 152.Fn ttyname , 153and 154.Fn ttyslot 155function 156appeared in 157.At v7 . 158.Sh BUGS 159The 160.Fn ttyname 161function leaves its result in an internal static object and returns 162a pointer to that object. Subsequent calls to 163.Fn ttyname 164will modify the same object. 165