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 88The 89.Fn ttyname 90function 91returns the name stored in a static buffer which will be overwritten 92on subsequent calls. 93The 94.Fn ttyname_r 95function 96takes a buffer and length as arguments to avoid this problem. 97.Pp 98The 99.Fn ttyslot 100function 101fetches the current process' control terminal number from the 102.Xr ttys 5 103file entry. 104.Sh RETURN VALUES 105The 106.Fn ttyname 107function 108returns the null terminated name if the device is found and 109.Fn isatty 110is true; otherwise 111a 112.Dv NULL 113pointer is returned. 114The 115.Fn ttyname_r 116function returns 0 if successful. 117Otherwise an error number is returned. 118.Pp 119The 120.Fn ttyslot 121function 122returns the unit number of the device file if found; otherwise 123the value zero is returned. 124.Sh FILES 125.Bl -tag -width ".Pa /etc/ttys" -compact 126.It Pa /dev/\(** 127.It Pa /etc/ttys 128.El 129.Sh ERRORS 130The 131.Fn ttyname_r 132may fail and return the following error codes: 133.Bl -tag -width Er 134.It Bq Er ENOTTY 135The 136.Fa fd 137argument 138is not a valid file descriptor. 139.It Bq Er ERANGE 140The 141.Fa bufsize 142argument 143is smaller than the length of the string to be returned. 144.El 145.Sh SEE ALSO 146.Xr ioctl 2 , 147.Xr ttys 5 148.Sh HISTORY 149The 150.Fn isatty , 151.Fn ttyname , 152and 153.Fn ttyslot 154functions 155appeared in 156.At v7 . 157The 158.Fn ttyname_r 159function 160appeared in 161.Fx 6.0 . 162