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.\" 34.Dd June 4, 1993 35.Dt TTYNAME 3 36.Os 37.Sh NAME 38.Nm ttyname , 39.Nm isatty , 40.Nm ttyslot 41.Nd get name of associated terminal (tty) from file descriptor 42.Sh SYNOPSIS 43.Fd #include <unistd.h> 44.Ft char * 45.Fn ttyname "int fd" 46.Ft int 47.Fn isatty "int fd" 48.Ft int 49.Fn ttyslot 50.Sh DESCRIPTION 51These functions operate on the system file descriptors for terminal 52type devices. These descriptors are not related to the standard 53.Tn I/O 54.Dv FILE 55typedef, but refer to the special device files found in 56.Pa /dev 57and named 58.Pa /dev/tty Ns Em xx 59and for which an entry exists 60in the initialization file 61.Pa /etc/ttys. 62(See 63.Xr ttys 5 . ) 64.Pp 65The 66.Fn isatty 67function 68determines if the file descriptor 69.Fa fd 70refers to a valid 71terminal type device. 72.Pp 73The 74.Fn ttyname 75function 76gets the related device name of 77a file descriptor for which 78.Fn isatty 79is true 80.Pp 81The 82.Fn ttyslot 83function 84fetches the current process' control terminal number from the 85.Xr ttys 5 86file entry. 87.Sh RETURN VALUES 88The 89.Fn ttyname 90function 91returns the null terminated name if the device is found and 92.Fn isatty 93is true; otherwise 94a 95.Dv NULL 96pointer is returned. 97.Pp 98The 99.Fn ttyslot 100function 101returns the unit number of the device file if found; otherwise 102the value zero is returned. 103.Sh FILES 104.Bl -tag -width /etc/ttys -compact 105.It Pa /dev/\(** 106.It Pa /etc/ttys 107.El 108.Sh SEE ALSO 109.Xr ioctl 2 , 110.Xr ttys 5 111.Sh HISTORY 112A 113.Fn isatty , 114.Fn ttyname , 115and 116.Fn ttyslot 117function 118appeared in 119.At v7 . 120.Sh BUGS 121The 122.Fn ttyname 123function leaves its result in an internal static object and returns 124a pointer to that object. Subsequent calls to 125.Fn ttyname 126will modify the same object. 127