-.TH TTYNAME 3 ""
-.AT 3
-.SH NAME
-ttyname, isatty, ttyslot \- find name of a terminal
-.SH SYNOPSIS
-.B char *ttyname(filedes)
-.PP
-.B isatty(filedes)
-.PP
-.B ttyslot()
-.SH DESCRIPTION
-.I Ttyname
-returns a pointer to the null-terminated path name
-of the terminal device associated with file descriptor
-.I filedes
-(this is a system file descriptor and has nothing to do with the
-standard I/O FILE typedef).
-.PP
-.I Isatty
-returns 1 if
-.I filedes
-is associated with a terminal device, 0 otherwise.
-.PP
-.I Ttyslot
-returns the number of the entry in the
-.IR ttys (5)
-file for the control terminal of the current process.
-.SH FILES
-/dev/\(**
-.br
-/etc/ttys
-.SH SEE ALSO
-ioctl(2), ttys(5)
-.SH DIAGNOSTICS
-.I Ttyname
-returns a null pointer (0) if
-.I filedes
-does not describe a terminal device in directory `/dev'.
-.PP
-.I Ttyslot
-returns 0 if `/etc/ttys' is inaccessible or if
-it cannot determine the control terminal.
-.SH BUGS
-The return value points to static data
-whose content is overwritten by each call.
+.\" 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 6.2 (Berkeley) 4/19/91
+.\"
+.Dd April 19, 1991
+.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 DESCRIPTION
+These functions operate on the system file descriptors for terminal
+type devices. These descriptors are not related to the standard
+.Tn I/O
+.Dv FILE
+typedef, but refer to the special device files found in
+.Pa /dev
+and named
+.Pa /dev/tty Ns Em xx
+and for which an entry exists
+in the initialization file
+.Pa /etc/ttys.
+(See
+.Xr ttys 5 . )
+.Pp
+The
+.Fn isatty
+function
+determines if the file descriptor
+.Fa fd
+refers to a valid
+terminal type device.
+.Pp
+The
+.Fn ttyname
+function
+gets the related device name of
+a file descriptor for which
+.Fn isatty
+is true
+.Pp
+The
+.Fn ttyslot
+function
+fetches the current process' control terminal number from the
+.Xr ttys 5
+file entry.
+.Sh RETURN VALUES
+The
+.Fn ttyname
+function
+returns the null terminated name if the device is found and
+.Fn isatty
+is true; otherwise
+a
+.Dv NULL
+pointer is returned.
+.Pp
+The
+.Fn ttyslot
+function
+returns the unit number of the device file if found; otherwise
+the 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 HISTORY
+A
+.Fn isatty ,
+.Fn ttyname ,
+and
+.Fn ttyslot
+function
+appeared in
+.At v7 .
+.Sh BUGS
+The
+.Fn ttyname
+function leaves its result in an internal static object and returns
+a pointer to that object. Subsequent calls to
+.Fn ttyname
+will modify the same object.
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