V10/man/adm/man3/ttyname.3

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.TH TTYNAME 3
.CT 2 comm_term
.SH NAME
ttyname, isatty, nametty \(mi find or set name of a terminal
.SH SYNOPSIS
.B char *ttyname(fildes)
.PP
.B isatty(fildes)
.PP
.B nametty(fildes, file)
.br
.B char *file;
.SH DESCRIPTION
.I Ttyname
returns a pointer to the null-terminated path name
of the terminal device associated with file descriptor
.IR fildes .
.PP
.I Isatty
returns 1 if
.I fildes
is associated with a terminal device,
0 otherwise.
.PP
.I Nametty
arranges that future opens of
.I file
will refer to
the stream opened on
.IR fildes .
.I File
must exist before
.I nametty
is called.
The arrangement is terminated
when the other end of the stream
is closed or hung up.
.SH FILES
.F /lib/ttydevs
	list of tty directories for
.I ttyname
.SH SEE ALSO
.IR fmount (2),
.IR ioctl (2)
.SH DIAGNOSTICS
.I Ttyname
returns
.L NULL
if
.I fildes
does not describe an entry in any of the directories
listed in
.FR /lib/ttydevs .
.PP
.I Nametty
returns 1 for success,
0 for failure
.RI ( file
does not exist,
.I fildes
is not a stream).
.SH BUGS
The return value of
.I ttyname
points to static data
whose content is overwritten by each call.
.br
If
.I fildes
connects to a remote machine, as when serving
.I dcon
or
.I rx
(see
.IR con (1)),
.I isatty
answers no, regardless of whether the stream 
leads ultimately to a terminal on the remote machine.
Similarly, when serving
.I ndcon
or
.I nrx,
it always answers yes.