.\" Copyright (c) 1991, 1993.\"	The Regents of the University of California.  All rights reserved..\".\" Redistribution and use in source and binary forms, with or without.\" modification, are permitted provided that the following conditions.\" are met:.\" 1. Redistributions of source code must retain the above copyright.\"    notice, this list of conditions and the following disclaimer..\" 2. Redistributions in binary form must reproduce the above copyright.\"    notice, this list of conditions and the following disclaimer in the.\"    documentation and/or other materials provided with the distribution..\" 3. All advertising materials mentioning features or use of this software.\"    must display the following acknowledgement:.\"	This product includes software developed by the University of.\"	California, Berkeley and its contributors..\" 4. Neither the name of the University nor the names of its contributors.\"    may be used to endorse or promote products derived from this software.\"    without specific prior written permission..\".\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION).\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF.\" SUCH DAMAGE..\".\"     @(#)ttyname.3	8.1 (Berkeley) 6/4/93.\".Dd June 4, 1993.Dt TTYNAME 3.Os.Sh NAME.Nm ttyname ,.Nm isatty ,.Nm ttyslot.Nd get name of associated terminal (tty) from file descriptor.Sh SYNOPSIS.Fd #include <unistd.h>.Ft char *.Fn ttyname "int fd".Ft int.Fn isatty "int fd".Ft int.Fn ttyslot .Sh DESCRIPTIONThese functions operate on the system file descriptors for terminaltype devices. These descriptors are not related to the standard.Tn I/O.Dv FILEtypedef, but refer to the special device files found in.Pa /devand named.Pa /dev/tty Ns Em xxand for which an entry existsin the initialization file.Pa /etc/ttys.(See.Xr ttys 5 . ).PpThe.Fn isattyfunctiondetermines if the file descriptor.Fa fdrefers to a validterminal type device..PpThe.Fn ttynamefunctiongets the related device name ofa file descriptor for which.Fn isattyis true.PpThe.Fn ttyslotfunctionfetches the current process' control terminal number from the.Xr ttys 5file entry..Sh RETURN VALUESThe.Fn ttynamefunctionreturns the null terminated name if the device is found and.Fn isattyis true; otherwise a.Dv NULLpointer is returned..PpThe.Fn ttyslotfunctionreturns the unit number of the device file if found; otherwisethe value zero is returned..Sh FILES.Bl -tag -width /etc/ttys -compact.It Pa /dev/\(**.It Pa /etc/ttys.El.Sh SEE ALSO.Xr ioctl 2 ,.Xr ttys 5.Sh HISTORYA.Fn isatty ,.Fn ttyname ,and.Fn ttyslotfunctionappeared in.At v7 ..Sh BUGSThe.Fn ttynamefunction leaves its result in an internal static object and returnsa pointer to that object. Subsequent calls to.Fn ttynamewill modify the same object.