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