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. 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.\" 30.Dd July 18, 2014 31.Dt TTYNAME 3 32.Os 33.Sh NAME 34.Nm ttyname , 35.Nm ttyname_r , 36.Nm isatty 37.Nd get name of associated terminal (tty) from file descriptor 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In unistd.h 42.Ft char * 43.Fn ttyname "int fd" 44.Ft int 45.Fn ttyname_r "int fd" "char *buf" "size_t len" 46.Ft int 47.Fn isatty "int fd" 48.Sh DESCRIPTION 49These functions operate on file descriptors for terminal type devices. 50.Pp 51The 52.Fn isatty 53function 54determines if the file descriptor 55.Fa fd 56refers to a valid 57terminal type device. 58.Pp 59The 60.Fn ttyname 61function 62gets the related device name of 63a file descriptor for which 64.Fn isatty 65is true. 66.Pp 67The 68.Fn ttyname 69function 70returns the name stored in a static buffer which will be overwritten 71on subsequent calls. 72The 73.Fn ttyname_r 74function 75takes a buffer and length as arguments to avoid this problem. 76.Sh RETURN VALUES 77The 78.Fn isatty 79function returns 1 if 80.Fa fd 81refers to a terminal type device; 82otherwise, it returns 0 and may set 83.Va errno 84to indicate the error. 85The 86.Fn ttyname 87function 88returns the null terminated name if the device is found and 89.Fn isatty 90is true; otherwise 91a 92.Dv NULL 93pointer is returned. 94The 95.Fn ttyname_r 96function returns 0 if successful. 97Otherwise an error number is returned. 98.Sh ERRORS 99These functions may fail if: 100.Bl -tag -width Er 101.It Bq Er EBADF 102The 103.Fa fd 104argument 105is not a valid file descriptor. 106.It Bq Er ENOTTY 107The file associated with 108.Fa fd 109is not a terminal. 110.El 111.Pp 112Additionally, 113.Fn ttyname_r 114may fail if: 115.Bl -tag -width Er 116.It Bq Er ERANGE 117The 118.Fa bufsize 119argument 120is smaller than the length of the string to be returned. 121.El 122.Sh SEE ALSO 123.Xr fdevname 3 , 124.Xr ptsname 3 , 125.Xr tcgetattr 3 , 126.Xr tty 4 127.Sh HISTORY 128The 129.Fn isatty 130and 131.Fn ttyname 132functions 133appeared in 134.At v7 . 135The 136.Fn ttyname_r 137function 138appeared in 139.Fx 6.0 . 140