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.Dd July 18, 2014 29.Dt TTYNAME 3 30.Os 31.Sh NAME 32.Nm ttyname , 33.Nm ttyname_r , 34.Nm isatty 35.Nd get name of associated terminal (tty) from file descriptor 36.Sh LIBRARY 37.Lb libc 38.Sh SYNOPSIS 39.In unistd.h 40.Ft char * 41.Fn ttyname "int fd" 42.Ft int 43.Fn ttyname_r "int fd" "char *buf" "size_t len" 44.Ft int 45.Fn isatty "int fd" 46.Sh DESCRIPTION 47These functions operate on file descriptors for terminal type devices. 48.Pp 49The 50.Fn isatty 51function 52determines if the file descriptor 53.Fa fd 54refers to a valid 55terminal type device. 56.Pp 57The 58.Fn ttyname 59function 60gets the related device name of 61a file descriptor for which 62.Fn isatty 63is true. 64.Pp 65The 66.Fn ttyname 67function 68returns the name stored in a static buffer which will be overwritten 69on subsequent calls. 70The 71.Fn ttyname_r 72function 73takes a buffer and length as arguments to avoid this problem. 74.Sh RETURN VALUES 75The 76.Fn isatty 77function returns 1 if 78.Fa fd 79refers to a terminal type device; 80otherwise, it returns 0 and may set 81.Va errno 82to indicate the error. 83The 84.Fn ttyname 85function 86returns the null terminated name if the device is found and 87.Fn isatty 88is true; otherwise 89a 90.Dv NULL 91pointer is returned. 92The 93.Fn ttyname_r 94function returns 0 if successful. 95Otherwise an error number is returned. 96.Sh ERRORS 97These functions may fail if: 98.Bl -tag -width Er 99.It Bq Er EBADF 100The 101.Fa fd 102argument 103is not a valid file descriptor. 104.It Bq Er ENOTTY 105The file associated with 106.Fa fd 107is not a terminal. 108.El 109.Pp 110Additionally, 111.Fn ttyname_r 112may fail if: 113.Bl -tag -width Er 114.It Bq Er ERANGE 115The 116.Fa bufsize 117argument 118is smaller than the length of the string to be returned. 119.El 120.Sh SEE ALSO 121.Xr fdevname 3 , 122.Xr ptsname 3 , 123.Xr tcgetattr 3 , 124.Xr tty 4 125.Sh HISTORY 126The 127.Fn isatty 128and 129.Fn ttyname 130functions 131appeared in 132.At v7 . 133The 134.Fn ttyname_r 135function 136appeared in 137.Fx 6.0 . 138