gno/usr.man/man3/ttyname.3

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.\"     @(#)ttyname.3	8.1 (Berkeley) 6/4/93
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.TH TTYNAME 3 "29 January 1997" GNO "Library Routines"
.SH NAME
.BR ttyname ,
.BR isatty ,
.BR ttyslot
\- get name of associated terminal (tty) from file descriptor
.SH SYNOPSIS
#include <unistd.h>
.sp 1
char *
\fBttyname\fR (int \fIfd\fR);
.br
int
\fBisatty\fR (int \fIfd\fR);
.br
int
\fBttyslot\fR (void);
.SH DESCRIPTION
These functions operate on the system file descriptors for terminal
type devices. These descriptors are not related to the standard I/O
.BR FILE
typedef, but refer to the special device named \fB.tty\fIxx\fR
and for which an entry exists
in the initialization file
.BR /etc/ttys .
(See
.BR ttys (5).)
.LP
The
.BR isatty 
function
determines if the file descriptor
.I fd
refers to a valid
terminal type device.
.LP
The
.BR ttyname 
function
gets the related device name of
a file descriptor for which
.BR isatty 
is true
.LP
The
.BR ttyslot 
function
fetches the current process' control terminal number from the
.BR ttys (5)
file entry.
.SH RETURN VALUES
The
.BR ttyname 
function
returns the null terminated name if the device is found and
.BR isatty 
is true; otherwise 
a
.BR NULL
pointer is returned.
.LP
The
.BR ttyslot 
function
returns the unit number of the device file if found; otherwise
the value zero is returned.
.SH FILES
.RS
.It Pa /dev/\(**
.It Pa /etc/ttys
.RE
.SH SEE ALSO
.BR ioctl (2),
.BR ttys (5)
.SH HISTORY
A
.BR isatty ,
.BR ttyname ,
and
.BR ttyslot 
function
appeared in v7.
.SH BUGS
The
.BR ttyname 
function leaves its result in an internal static object and returns
a pointer to that object. Subsequent calls to
.BR ttyname 
will modify the same object.