205 lines
5.2 KiB
Groff
205 lines
5.2 KiB
Groff
.\" $NetBSD: ttyname.3,v 1.24 2012/06/03 21:42:46 joerg Exp $
|
|
.\"
|
|
.\" 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. 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 1, 2012
|
|
.Dt TTYNAME 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm ttyname ,
|
|
.Nm ttyname_r ,
|
|
.Nm isatty ,
|
|
.Nm ttyslot
|
|
.Nd get name of associated terminal (tty) from file descriptor
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In unistd.h
|
|
.Ft char *
|
|
.Fn ttyname "int fd"
|
|
.Ft int
|
|
.Fn ttyname_r "int fd" "char *buf" "size_t len"
|
|
.Ft int
|
|
.Fn isatty "int fd"
|
|
.In stdlib.h
|
|
.Ft int
|
|
.Fn ttyslot "void"
|
|
.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 ) ,
|
|
or for pseudo-terminal devices created in ptyfs and named
|
|
.Pa /dev/pts/ Ns Em n .
|
|
.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.
|
|
The
|
|
.Fn ttyname_r
|
|
is the reentrant version of the above, and it places the results in
|
|
.Fa buf .
|
|
If there is not enough space to place the results (indicated by
|
|
.Fa len ) ,
|
|
then it returns an error.
|
|
.Pp
|
|
The
|
|
.Fn ttyslot
|
|
function
|
|
fetches the current process' control terminal number from the
|
|
.Xr ttys 5
|
|
file entry.
|
|
If the terminal is a pseudo-terminal, and there is no special entry
|
|
in the
|
|
.Xr ttys 5
|
|
file for it, the slot number returned is 1 + (last slot number) +
|
|
minor(tty).
|
|
This will return a consistent and unique number for each pseudo-terminal
|
|
device without requiring one to enumerate all of them in
|
|
.Xr ttys 5 .
|
|
.Sh IMPLEMENTATION NOTES
|
|
As an optimisation, these functions attempt to obtain information about
|
|
all devices from the
|
|
.Pa /var/run/dev.cdb
|
|
database, if it exists.
|
|
If the database exists but is out of date, then these functions
|
|
may produce incorrect results.
|
|
The database should be updated using the
|
|
.Xr dev_mkdb 8
|
|
command.
|
|
.Sh RETURN VALUES
|
|
The
|
|
.Fn ttyname
|
|
function returns the NUL-terminated name if the device is found and
|
|
.Fn isatty
|
|
is true; otherwise
|
|
a
|
|
.Dv NULL
|
|
pointer is returned and
|
|
.Va errno
|
|
is set to indicate the error.
|
|
.Pp
|
|
The
|
|
.Fn ttyname_r
|
|
functions returns 0 on success and an error code on failure.
|
|
.Pp
|
|
The
|
|
.Fn isatty
|
|
function returns 1 if
|
|
.Fa fd
|
|
is associated with a terminal device; otherwise it returns 0 and
|
|
.Va errno
|
|
is set to indicate the error.
|
|
.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 ERRORS
|
|
The
|
|
.Fn ttyname ,
|
|
.Fn ttyname_r ,
|
|
and
|
|
.Fn isatty
|
|
functions will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EBADF
|
|
The
|
|
.Fa fd
|
|
argument is not a valid file descriptor.
|
|
.It Bq Er ENOTTY
|
|
The
|
|
.Fa fd
|
|
argument does not refer to a terminal device.
|
|
.El
|
|
.Pp
|
|
The
|
|
.Fn ttyname_r
|
|
function will also fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er ENOENT
|
|
The terminal device is not found.
|
|
This can happen if the device node has been removed after it was opened.
|
|
.It Bq Er ERANGE
|
|
The buffer provided is not large enough to fit the result.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr ioctl 2 ,
|
|
.Xr ttys 5 ,
|
|
.Xr dev_mkdb 8
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn ttyname
|
|
and
|
|
.Fn isatty
|
|
functions conform to
|
|
.St -p1003.1-90 .
|
|
.Sh HISTORY
|
|
.Fn isatty ,
|
|
.Fn ttyname ,
|
|
and
|
|
.Fn ttyslot
|
|
functions appeared in
|
|
.At v7 .
|
|
.\" Use of the .Pa /var/run/dev.cdb file was added in netBSD 6.0.
|
|
.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.
|