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.\" $FreeBSD: src/lib/libc/gen/ttyname.3,v 1.14 2007/01/09 00:27:55 imp Exp $ 30.\" $DragonFly: src/lib/libc/gen/ttyname.3,v 1.3 2005/11/19 22:32:53 swildner Exp $ 31.\" 32.Dd March 22, 2009 33.Dt TTYNAME 3 34.Os 35.Sh NAME 36.Nm ttyname , 37.Nm ttyname_r , 38.Nm isatty , 39.Nm ttyslot 40.Nd get name of associated terminal (tty) from file descriptor 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In unistd.h 45.Ft char * 46.Fn ttyname "int fd" 47.Ft int 48.Fn ttyname_r "int fd" "char *buf" "size_t len" 49.Ft int 50.Fn isatty "int fd" 51.Ft int 52.Fn ttyslot void 53.Sh DESCRIPTION 54These functions operate on the system file descriptors for terminal 55type devices. 56These descriptors are not related to the standard 57.Tn I/O 58.Dv FILE 59typedef, but refer to the special device files found in 60.Pa /dev 61and named 62.Pa /dev/tty Ns Ar xx 63and for which an entry exists 64in the initialization file 65.Pa /etc/ttys . 66(See 67.Xr ttys 5 . ) 68.Pp 69The 70.Fn isatty 71function 72determines if the file descriptor 73.Fa fd 74refers to a valid 75terminal type device. 76.Pp 77The 78.Fn ttyname 79function 80gets the related device name of 81a file descriptor for which 82.Fn isatty 83is true. 84.Pp 85The 86.Fn ttyname 87function 88returns the name stored in a static buffer which will be overwritten 89on subsequent calls. 90The 91.Fn ttyname_r 92function 93takes a buffer and length as arguments to avoid this problem. 94.Pp 95The 96.Fn ttyslot 97function 98fetches the current process' control terminal number from the 99.Xr ttys 5 100file entry. 101.Sh RETURN VALUES 102The 103.Fn isatty 104function 105returns 1 if the file descriptor refers to a valid terminal 106device and 0 otherwise. 107.Pp 108The 109.Fn ttyname 110function 111returns the null terminated name if the device is found and 112.Fn isatty 113is true; otherwise 114a 115.Dv NULL 116pointer is returned. 117The 118.Fn ttyname_r 119function returns 0 if successful. 120Otherwise an error number is returned. 121.Pp 122The 123.Fn ttyslot 124function 125returns the unit number of the device file if found; otherwise 126the value zero is returned. 127.Sh FILES 128.Bl -tag -width ".Pa /etc/ttys" -compact 129.It Pa /dev/\(** 130.It Pa /etc/ttys 131.El 132.Sh ERRORS 133The 134.Fn ttyname , 135.Fn ttyname_r , 136and 137.Fn isatty 138functions 139may fail and return the following error codes: 140.Bl -tag -width Er 141.It Bq Er EBADF 142The 143.Fa fd 144is not a valid open file descriptor. 145.It Bq Er ENOTTY 146The 147.Fa fd 148is not associated with a terminal. 149.It Bq Er ERANGE 150The 151.Fa bufsize 152argument 153is smaller than the length of the string to be returned. 154.El 155.Sh SEE ALSO 156.Xr ioctl 2 , 157.Xr ttys 5 158.Sh HISTORY 159The 160.Fn isatty , 161.Fn ttyname , 162and 163.Fn ttyslot 164functions 165appeared in 166.At v7 . 167The 168.Fn ttyname_r 169function 170appeared in 171.Fx 6.0 . 172