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. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)ttyname.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD$ 34.\" 35.Dd May 14, 2005 36.Dt TTYNAME 3 37.Os 38.Sh NAME 39.Nm ttyname , 40.Nm ttyname_r , 41.Nm isatty , 42.Nm ttyslot 43.Nd get name of associated terminal (tty) from file descriptor 44.Sh LIBRARY 45.Lb libc 46.Sh SYNOPSIS 47.In unistd.h 48.Ft char * 49.Fn ttyname "int fd" 50.Ft int 51.Fn ttyname_r "int fd" "char *buf" "size_t len" 52.Ft int 53.Fn isatty "int fd" 54.Ft int 55.Fn ttyslot void 56.Sh DESCRIPTION 57These functions operate on the system file descriptors for terminal 58type devices. 59These descriptors are not related to the standard 60.Tn I/O 61.Dv FILE 62typedef, but refer to the special device files found in 63.Pa /dev 64and named 65.Pa /dev/tty Ns Ar xx 66and for which an entry exists 67in the initialization file 68.Pa /etc/ttys . 69(See 70.Xr ttys 5 . ) 71.Pp 72The 73.Fn isatty 74function 75determines if the file descriptor 76.Fa fd 77refers to a valid 78terminal type device. 79.Pp 80The 81.Fn ttyname 82function 83gets the related device name of 84a file descriptor for which 85.Fn isatty 86is true. 87.Pp 88.Fn ttyname 89returns the name stored in a static buffer which will be overwritten 90on subsequent calls. 91.Fn ttyname_r 92takes a buffer and length as arguments to avoid this problem. 93.Pp 94The 95.Fn ttyslot 96function 97fetches the current process' control terminal number from the 98.Xr ttys 5 99file entry. 100.Sh RETURN VALUES 101The 102.Fn ttyname 103function 104returns the null terminated name if the device is found and 105.Fn isatty 106is true; otherwise 107a 108.Dv NULL 109pointer is returned. 110The 111.Fn ttyname_r 112function returns 0 if successful. Otherwise 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 ERRORS 120.Fn ttyname_r 121may return the following error codes: 122.Bl -tag -width Er 123.It Bq Er ENOTTY 124.Fa fd 125is not a valid file descriptor. 126.It Bq Er ERANGE 127.Fa bufsize 128is smaller than the length of the string to be returned. 129.Sh FILES 130.Bl -tag -width /etc/ttys -compact 131.It Pa /dev/\(** 132.It Pa /etc/ttys 133.El 134.Sh SEE ALSO 135.Xr ioctl 2 , 136.Xr ttys 5 137.Sh HISTORY 138A 139.Fn isatty , 140.Fn ttyname , 141and 142.Fn ttyslot 143function 144appeared in 145.At v7 . 146.Fn ttyname_r 147appeared in 148.Fx 6.0 . 149