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.In unistd.h 47.Ft char * 48.Fn ttyname "int fd" 49.Ft char * 50.Fn ttyname_r "int fd" "char *buf" "size_t len" 51.Ft int 52.Fn isatty "int fd" 53.Ft int 54.Fn ttyslot void 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 Ar 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. 103.Pp 104The 105.Fn ttyslot 106function 107returns the unit number of the device file if found; otherwise 108the value zero is returned. 109.Sh FILES 110.Bl -tag -width /etc/ttys -compact 111.It Pa /dev/\(** 112.It Pa /etc/ttys 113.El 114.Sh SEE ALSO 115.Xr ioctl 2 , 116.Xr ttys 5 117.Sh HISTORY 118A 119.Fn isatty , 120.Fn ttyname , 121and 122.Fn ttyslot 123function 124appeared in 125.At v7 . 126.Sh BUGS 127The 128.Fn ttyname 129function leaves its result in an internal static object and returns 130a pointer to that object. 131Subsequent calls to 132.Fn ttyname 133will modify the same object. 134