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: src/lib/libc/gen/ttyname.3,v 1.5.2.3 2001/12/14 18:33:51 ru Exp $ 34.\" $DragonFly: src/lib/libc/gen/ttyname.3,v 1.3 2005/11/19 22:32:53 swildner Exp $ 35.\" 36.Dd March 22, 2009 37.Dt TTYNAME 3 38.Os 39.Sh NAME 40.Nm ttyname , 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 char * 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 Em 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_r 90function is a thread-safe version of 91.Fn ttyname . 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 isatty 102function 103returns 1 if the file descriptor refers to a valid terminal 104device and 0 otherwise. 105.Pp 106The 107.Fn ttyname 108function 109returns the null terminated name if the device is found and 110.Fn isatty 111is true; otherwise 112a 113.Dv NULL 114pointer is returned. 115.Pp 116The 117.Fn ttyslot 118function 119returns the unit number of the device file if found; otherwise 120the value zero is returned. 121.Sh FILES 122.Bl -tag -width /etc/ttys -compact 123.It Pa /dev/\(** 124.It Pa /etc/ttys 125.El 126.Sh ERRORS 127The 128.Fn ttyname 129and 130.Fn isatty 131functions 132may fail if: 133.Bl -tag -width Er 134.It Bq Er EBADF 135The 136.Fa fd 137is not a valid open file descriptor. 138.It Bq Er ENOTTY 139The 140.Fa fd 141is not associated with a terminal. 142.El 143.Sh SEE ALSO 144.Xr ioctl 2 , 145.Xr ttys 5 146.Sh HISTORY 147A 148.Fn isatty , 149.Fn ttyname , 150and 151.Fn ttyslot 152function 153appeared in 154.At v7 . 155.Sh BUGS 156The 157.Fn ttyname 158function leaves its result in an internal static object and returns 159a pointer to that object. 160Subsequent calls to 161.Fn ttyname 162will modify the same object. 163