1.\" Copyright (c) 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)ttyname.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD$ 34.\" 35.Dd June 4, 1993 36.Dt TTYNAME 3 37.Os 38.Sh NAME 39.Nm ttyname , 40.Nm isatty , 41.Nm ttyslot 42.Nd get name of associated terminal (tty) from file descriptor 43.Sh LIBRARY 44.Lb libc 45.Sh SYNOPSIS 46.Fd #include <unistd.h> 47.Ft char * 48.Fn ttyname "int fd" 49.Ft int 50.Fn isatty "int fd" 51.Ft int 52.Fn ttyslot void 53.Sh DESCRIPTION 54These functions operate on the system file descriptors for terminal 55type devices. 56These descriptors are not related to the standard 57.Tn I/O 58.Dv FILE 59typedef, but refer to the special device files found in 60.Pa /dev 61and named 62.Pa /dev/tty Ns Em xx 63and for which an entry exists 64in the initialization file 65.Pa /etc/ttys . 66(See 67.Xr ttys 5 . ) 68.Pp 69The 70.Fn isatty 71function 72determines if the file descriptor 73.Fa fd 74refers to a valid 75terminal type device. 76.Pp 77The 78.Fn ttyname 79function 80gets the related device name of 81a file descriptor for which 82.Fn isatty 83is true 84.Pp 85The 86.Fn ttyslot 87function 88fetches the current process' control terminal number from the 89.Xr ttys 5 90file entry. 91.Sh RETURN VALUES 92The 93.Fn ttyname 94function 95returns the null terminated name if the device is found and 96.Fn isatty 97is true; otherwise 98a 99.Dv NULL 100pointer is returned. 101.Pp 102The 103.Fn ttyslot 104function 105returns the unit number of the device file if found; otherwise 106the value zero is returned. 107.Sh FILES 108.Bl -tag -width /etc/ttys -compact 109.It Pa /dev/\(** 110.It Pa /etc/ttys 111.El 112.Sh SEE ALSO 113.Xr ioctl 2 , 114.Xr ttys 5 115.Sh HISTORY 116A 117.Fn isatty , 118.Fn ttyname , 119and 120.Fn ttyslot 121function 122appeared in 123.At v7 . 124.Sh BUGS 125The 126.Fn ttyname 127function leaves its result in an internal static object and returns 128a pointer to that object. 129Subsequent calls to 130.Fn ttyname 131will modify the same object. 132