167 lines
4.1 KiB
Groff
167 lines
4.1 KiB
Groff
.\" $NetBSD: ttyname.3,v 1.12 2002/10/01 16:48:35 wiz Exp $
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.\"
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.\" Copyright (c) 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)ttyname.3 8.1 (Berkeley) 6/4/93
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.\"
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.Dd June 4, 1993
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.Dt TTYNAME 3
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.Os
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.Sh NAME
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.Nm ttyname ,
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.Nm isatty ,
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.Nm ttyslot
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.Nd get name of associated terminal (tty) from file descriptor
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.Fd #include \*[Lt]unistd.h\*[Gt]
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.Ft char *
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.Fn ttyname "int fd"
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.Ft int
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.Fn isatty "int fd"
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.Fd #include \*[Lt]stdlib.h\*[Gt]
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.Ft int
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.Fn ttyslot
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.Sh DESCRIPTION
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These functions operate on the system file descriptors for terminal
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type devices.
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These descriptors are not related to the standard
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.Tn I/O
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.Dv FILE
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typedef, but refer to the special device files found in
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.Pa /dev
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and named
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.Pa /dev/tty Ns Em xx
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and for which an entry exists
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in the initialization file
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.Pa /etc/ttys .
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(See
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.Xr ttys 5 . )
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.Pp
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The
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.Fn isatty
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function
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determines if the file descriptor
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.Fa fd
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refers to a valid
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terminal type device.
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.Pp
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The
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.Fn ttyname
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function
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gets the related device name of
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a file descriptor for which
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.Fn isatty
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is true.
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.Pp
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The
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.Fn ttyslot
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function
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fetches the current process' control terminal number from the
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.Xr ttys 5
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file entry.
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.Sh RETURN VALUES
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The
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.Fn ttyname
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function
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returns the null terminated name if the device is found and
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.Fn isatty
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is true; otherwise
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a
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.Dv NULL
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pointer is returned and
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.Va errno
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is set to indicate the error.
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.Pp
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The
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.Fn isatty
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function returns 1 if
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.Fa fd
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is associated with a terminal device; otherwise it returns 0 and
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.Va errno
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is set to indicate the error.
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.Pp
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The
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.Fn ttyslot
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function
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returns the unit number of the device file if found; otherwise
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the value zero is returned.
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.Sh FILES
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.Bl -tag -width /etc/ttys -compact
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.It Pa /dev/\(**
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.It Pa /etc/ttys
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.El
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.Sh ERRORS
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The
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.Fn ttyname
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and
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.Fn isatty
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functions will fail if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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The
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.Fa fd
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argument is not a valid file descriptor.
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.It Bq Er ENOTTY
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The
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.Fa fd
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argument does not refer to a terminal device.
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.El
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.Sh SEE ALSO
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.Xr ioctl 2 ,
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.Xr ttys 5
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.Sh STANDARDS
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The
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.Fn ttyname
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and
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.Fn isatty
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functions conform to
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.St -p1003.1-90 .
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.Sh HISTORY
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A
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.Fn isatty ,
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.Fn ttyname ,
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and
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.Fn ttyslot
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function
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appeared in
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.At v7 .
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.Sh BUGS
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The
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.Fn ttyname
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function leaves its result in an internal static object and returns
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a pointer to that object.
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Subsequent calls to
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.Fn ttyname
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will modify the same object.
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