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 July 18, 2014 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 isatty 80function returns 1 if 81.Fa fd 82refers to a terminal type device; 83otherwise, it returns 0 and may set 84.Va errno 85to indicate the error. 86The 87.Fn ttyname 88function 89returns the null terminated name if the device is found and 90.Fn isatty 91is true; otherwise 92a 93.Dv NULL 94pointer is returned. 95The 96.Fn ttyname_r 97function returns 0 if successful. 98Otherwise an error number is returned. 99.Sh ERRORS 100These functions may fail if: 101.Bl -tag -width Er 102.It Bq Er EBADF 103The 104.Fa fd 105argument 106is not a valid file descriptor. 107.It Bq Er ENOTTY 108The file associated with 109.Fa fd 110is not a terminal. 111.El 112.Pp 113Additionally, 114.Fn ttyname_r 115may fail if: 116.Bl -tag -width Er 117.It Bq Er ERANGE 118The 119.Fa bufsize 120argument 121is smaller than the length of the string to be returned. 122.El 123.Sh SEE ALSO 124.Xr fdevname 3 , 125.Xr ptsname 3 , 126.Xr tcgetattr 3 , 127.Xr tty 4 128.Sh HISTORY 129The 130.Fn isatty 131and 132.Fn ttyname 133functions 134appeared in 135.At v7 . 136The 137.Fn ttyname_r 138function 139appeared in 140.Fx 6.0 . 141