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.\" 4. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)ttyname.3 8.1 (Berkeley) 6/4/93 29.\" $FreeBSD$ 30.\" 31.Dd May 14, 2005 32.Dt TTYNAME 3 33.Os 34.Sh NAME 35.Nm ttyname , 36.Nm ttyname_r , 37.Nm isatty 38.Nd get name of associated terminal (tty) from file descriptor 39.Sh LIBRARY 40.Lb libc 41.Sh SYNOPSIS 42.In unistd.h 43.Ft char * 44.Fn ttyname "int fd" 45.Ft int 46.Fn ttyname_r "int fd" "char *buf" "size_t len" 47.Ft int 48.Fn isatty "int fd" 49.Sh DESCRIPTION 50These functions operate on file descriptors for terminal type devices. 51.Pp 52The 53.Fn isatty 54function 55determines if the file descriptor 56.Fa fd 57refers to a valid 58terminal type device. 59.Pp 60The 61.Fn ttyname 62function 63gets the related device name of 64a file descriptor for which 65.Fn isatty 66is true. 67.Pp 68The 69.Fn ttyname 70function 71returns the name stored in a static buffer which will be overwritten 72on subsequent calls. 73The 74.Fn ttyname_r 75function 76takes a buffer and length as arguments to avoid this problem. 77.Sh RETURN VALUES 78The 79.Fn ttyname 80function 81returns the null terminated name if the device is found and 82.Fn isatty 83is true; otherwise 84a 85.Dv NULL 86pointer is returned. 87The 88.Fn ttyname_r 89function returns 0 if successful. 90Otherwise an error number is returned. 91.Sh ERRORS 92The 93.Fn ttyname_r 94may fail and return the following error codes: 95.Bl -tag -width Er 96.It Bq Er ENOTTY 97The 98.Fa fd 99argument 100is not a valid file descriptor. 101.It Bq Er ERANGE 102The 103.Fa bufsize 104argument 105is smaller than the length of the string to be returned. 106.El 107.Sh SEE ALSO 108.Xr fdevname 3 , 109.Xr ptsname 3 , 110.Xr tcgetattr 3 , 111.Xr tty 4 112.Sh HISTORY 113The 114.Fn isatty 115and 116.Fn ttyname 117functions 118appeared in 119.At v7 . 120The 121.Fn ttyname_r 122function 123appeared in 124.Fx 6.0 . 125